/***************************************************************************
 * PHAST: PHylogenetic Analysis with Space/Time models
 * Copyright (c) 2002-2005 University of California, 2006-2010 Cornell 
 * University.  All rights reserved.
 *
 * This source code is distributed under a BSD-style license.  See the
 * file LICENSE.txt for details.
 ***************************************************************************/

/* $Id: tree_model.c,v 1.42 2009-03-20 18:16:48 agd27 Exp $ */

#include <tree_model.h>
#include <subst_mods.h>
#include <stacks.h>
#include <stringsplus.h>
#include <ctype.h>
#include <numerical_opt.h>
#include <markov_matrix.h>
#include <tree_likelihoods.h>
#include <time.h>
#include <sys/time.h>
#include <sufficient_stats.h>
#include <matrix.h>
#include <sys/types.h>
#include <unistd.h>
#include <dgamma.h>
#include <math.h>
#include <misc.h>

#define ALPHABET_TAG "ALPHABET:"
#define BACKGROUND_TAG "BACKGROUND:"
#define ORDER_TAG "ORDER:"
#define SUBST_MOD_TAG "SUBST_MOD:"
#define SUBST_MOD_PARAMS_TAG "SUBST_MOD_PARAMS:"
#define RATE_MATRIX_TAG "RATE_MAT:"
#define TREE_TAG "TREE:"
#define EVEC_TAG "EVEC_MAT:"
#define EVAL_TAG "EVAL_MAT:"
#define INV_EVEC_TAG "INV_EVEC_MAT:"
#define LNL_TAG "TRAINING_LNL:"
#define ALPHA_TAG "ALPHA:"
#define NRATECATS_TAG "NRATECATS:"
#define RATE_CONSTS_TAG "RATE_CONSTS:"
#define RATE_WEIGHTS_TAG "RATE_WEIGHTS:"
#define ALT_MODEL_TAG "ALT_SUBST_MOD:"
#define SELECTION_TAG "SELECTION_PAR:"
#define BGC_TAG "BGC_PAR:"


#define BGC_SEL_LIMIT 200.0

/* internal functions */
double tm_likelihood_wrapper(Vector *params, void *data);
double tm_multi_likelihood_wrapper(Vector *params, void *data);


/* tree == NULL implies weight matrix (most other params ignored in
   this case) */
TreeModel *tm_new(TreeNode *tree, MarkovMatrix *rate_matrix, 
                  Vector *backgd_freqs, subst_mod_type subst_mod, 
                  char *alphabet, int nratecats, double alpha, 
                  List *rate_consts, int root_leaf_id) {
  TreeModel *tm = (TreeModel*)smalloc(sizeof(TreeModel));
  int i, j, nstate=-1;

  tm->subst_mod = subst_mod;
  tm->order = tm_order(subst_mod);

  tm->backgd_freqs = backgd_freqs;
  tm->tree = tree;
  tm->alpha = alpha;
  tm->root_leaf_id = root_leaf_id;
  tm->empirical_rates = 0;      /* default (see below) */
  if (rate_matrix != NULL)
    nstate = rate_matrix->size;
  else if (backgd_freqs != NULL)
    nstate = backgd_freqs->size;
  else if (alphabet != NULL)
    nstate = int_pow((int)strlen(alphabet), tm->order+1);
  else die("ERROR: tm_new needs either alphabet, rate_matrix, or backgd to get number of states\n");

  if (tree == NULL) {           /* weight matrix */
    tm->rate_matrix = rate_matrix != NULL ? rate_matrix :
      mm_new(nstate, alphabet, CONTINUOUS);
                                /* dummy rate matrix; for now, this is
                                   the only way to store the
                                   alphabet */
    tm->P = NULL;
    tm->rK = tm->freqK = NULL;
    tm->nratecats = 1;
  }
  else {                        /* full tree model */
    tm->rate_matrix = rate_matrix != NULL ? rate_matrix :
      mm_new(nstate, alphabet, CONTINUOUS);

    if (subst_mod_is_reversible(subst_mod))
      mm_set_eigentype(tm->rate_matrix, REAL_NUM);
    /* can assume real eigenvalues and eigenvectors in this case */

    /* set up probability matrices and rate variation stuff */
    tm->nratecats = nratecats;
    tm->P = (MarkovMatrix***)smalloc(tree->nnodes * sizeof(MarkovMatrix**));
    for (i = 0; i < tree->nnodes; i++) {
      tm->P[i] = (MarkovMatrix**)smalloc(nratecats * sizeof(MarkovMatrix*));
      for (j = 0; j < nratecats; j++) tm->P[i][j] = NULL;
    }

    tm->rK = (double*)smalloc(nratecats * sizeof(double));
    tm->freqK = (double*)smalloc(nratecats * sizeof(double));

    if (rate_consts != NULL) {  /* empirical rate model */
      double interval_size, initalpha = (alpha > 0 ? alpha : 1);
      tm->empirical_rates = 1;
      if (nratecats != lst_size(rate_consts) )
        die("ERROR: number of explicitly defined rate constants must equal number of rate categories.\n");
      for (i = 0; i < nratecats; i++) {
        tm->rK[i] = lst_get_dbl(rate_consts, i);
        interval_size = tm->rK[i] - (i > 0 ? tm->rK[i-1] : 0);
        tm->freqK[i] = gamma_pdf(tm->rK[i], initalpha, 1/initalpha) * 
          interval_size; 
        /* init to approx gamma with shape param alpha. */
      }
      normalize_probs(tm->freqK, tm->nratecats);
    }
    else {                      /* dgamma or no rate variation; if
                                   dgamma, rates will be filled out
                                   as needed, according to alpha */
      tm->rK[0] = tm->freqK[0] = 1;
      for (i = 1; i < nratecats; i++) tm->rK[i] = tm->freqK[i] = 0;
    }
  }

  /* various attributes used when fitting a model to an alignment */
  tm->msa = NULL;
  tm->msa_seq_idx = NULL;
  tm->lnL = NULL_LOG_LIKELIHOOD;
  tm->tree_posteriors = NULL;
  tm->use_conditionals = 0;
  tm->category = -1;
  tm->allow_but_penalize_gaps = 0;
  tm->allow_gaps = 1;
  tm->inform_reqd = FALSE;
  tm->estimate_backgd = 0;
  tm->estimate_branchlens = TM_BRANCHLENS_ALL;
  tm->scale = 1;
  tm->subtree_root = NULL;
  tm->scale_sub = 1;
  tm->scale_sub_bound = NB;
  tm->in_subtree = NULL;
  tm->estimate_ratemat = TRUE;
  tm->ignore_branch = NULL;
  tm->alt_subst_mods = NULL;
  tm->alt_subst_mods_ptr = NULL;
  tm->all_params = NULL;
  tm->param_map = NULL;
  tm->selection = 0.0;
  tm->site_model = FALSE;
  tm->scale_idx = tm->bl_idx = tm->backgd_idx = 
    tm->ratevar_idx = tm->ratematrix_idx = 
    tm->selection_idx = -1;
  tm->rate_matrix_param_row = tm->rate_matrix_param_col = NULL;
  tm->noopt_arg = NULL;
  tm->eqfreq_sym = (tm->subst_mod == SSREV);
  tm->bound_arg = NULL;
  tm->scale_during_opt = 0;
  tm->iupac_inv_map = NULL;
  return tm;
}

/** Re-initialize a tree model with an altered substitution model,
    number of rate categories, alpha, set of rate consts, or set of
    rate weights. */ 
void tm_reinit(TreeModel *tm,   /* TreeModel object to reinitialize  */
               subst_mod_type new_subst_mod, 
                                /* New substitution model */
               int new_nratecats, 
                                /* New number of rate categories */
               double new_alpha, 
                                /* New alpha parameter (ignored if
                                   new_nratecats == 1) */
               List *new_rate_consts, 
                                /* New list of explicit rate
                                   constants.  If non-NULL, implies
                                   use of empirical rates. */
               List *new_rate_weights
                                /* New list of explicit rate weights
                                   (mixing proportions).  Will be
                                   normalized automatically.  If
                                   new_rate_consts != NULL and
                                   new_rate_weights == NULL, weights
                                   will be initialized to approx gamma
                                   distrib. defined by alpha */
               ) {
  int i, j;
  int old_nratecats = tm->nratecats;
  if (new_nratecats < 1)
    die("ERROR tm_reinit: new_nratecats=%i\n", new_nratecats);
  if (tm->alt_subst_mods != NULL && new_nratecats != tm->nratecats)
    die("ERROR: tm_reinit hasn't yet implemented lineage-specific models\n");
  tm_free_rmp(tm);
  tm->rate_matrix_param_row = tm->rate_matrix_param_col = NULL;
  if (tm_order(new_subst_mod) != tm->order)
    die("ERROR: Cannot initialize tree model from model of different order.\n");
  tm->subst_mod = new_subst_mod;
  tm->nratecats = new_nratecats;
  tm->alpha = (tm->nratecats > 1 ? new_alpha : 0);
  tm->empirical_rates = new_rate_consts != NULL ? 1 : 0;
  tm->rK = srealloc(tm->rK, new_nratecats * sizeof(double));
  tm->freqK = srealloc(tm->freqK, new_nratecats * sizeof(double));

  if (new_rate_consts != NULL) {  /* empirical rate model */
    double interval_size, initalpha = (new_alpha > 0 ? new_alpha : 1);
    if (new_nratecats != lst_size(new_rate_consts) ||
        (new_rate_weights != NULL && new_nratecats != lst_size(new_rate_weights)))
      die("ERROR: number of explicitly defined rate constants and/or rate weights must equal number of rate categories.\n");
    for (i = 0; i < new_nratecats; i++) {
      tm->rK[i] = lst_get_dbl(new_rate_consts, i);
      if (new_rate_weights != NULL)
        tm->freqK[i] = lst_get_dbl(new_rate_weights, i);
      else {
        interval_size = tm->rK[i] - (i > 0 ? tm->rK[i-1] : 0);
        tm->freqK[i] = gamma_pdf(tm->rK[i], initalpha, 1/initalpha) * 
          interval_size; 
        /* init to approx gamma with shape param alpha. */
      }
    }

    //if using approx gamma to initialize freqK, check and see if
    //some of the rates are the same.  If so, divide the mass evenly
    //between them.
    if (new_rate_weights == NULL) {
      int j, k;
      for (i=0; i < new_nratecats; i++) {
	for (j=i; j < new_nratecats; j++) 
	  if (tm->rK[i] != tm->rK[j]) break;
	j--;
	if (j > i) {
	  for (k=i; k <=j; k++)
	    tm->freqK[k] = tm->rK[i]/(double)(j-i+1);
	}
      }
    }
    normalize_probs(tm->freqK, tm->nratecats);
  }
  else {                        /* dgamma or no rate variation */
    tm->rK[0] = tm->freqK[0] = 1;
    for (i = 1; i < tm->nratecats; i++) tm->rK[i] = tm->freqK[i] = 0;
  }

  for (i = 0; i < tm->tree->nnodes; i++) {
    tm->P[i] = srealloc(tm->P[i], new_nratecats * sizeof(MarkovMatrix*));
    for (j = old_nratecats; j < new_nratecats; j++) tm->P[i][j] = NULL;
  }

  if (subst_mod_is_reversible(new_subst_mod) && 
      tm->rate_matrix->eigentype == COMPLEX_NUM)
    mm_set_eigentype(tm->rate_matrix, REAL_NUM);
  else if (!subst_mod_is_reversible(new_subst_mod) && 
	   tm->rate_matrix->eigentype == REAL_NUM)
    mm_set_eigentype(tm->rate_matrix, COMPLEX_NUM);    
  if (tm->subst_mod == SSREV)
    tm->eqfreq_sym = TRUE;
}

void tm_free(TreeModel *tm) {
  int i, j;
  if (tm->tree != NULL) {
    if (tm->rate_matrix_param_row != NULL)
      tm_free_rmp(tm);
    if (tm->alt_subst_mods != NULL) {
      for (i=0; i<lst_size(tm->alt_subst_mods); i++) 
	tm_free_alt_subst_mod(lst_get_ptr(tm->alt_subst_mods, i));
      lst_free(tm->alt_subst_mods);
    }
    if (tm->alt_subst_mods_ptr != NULL) {
      for (i=0; i < tm->tree->nnodes; i++)
	sfree(tm->alt_subst_mods_ptr[i]);
      sfree(tm->alt_subst_mods_ptr);
    }
    for (i = 0; i < tm->tree->nnodes; i++) {
      for (j = 0; j < tm->nratecats; j++)
        if (tm->P[i][j] != NULL) mm_free(tm->P[i][j]);
      sfree(tm->P[i]);
    }
    if (tm->msa_seq_idx != NULL) sfree(tm->msa_seq_idx);
    sfree(tm->P);
    sfree(tm->rK);
    sfree(tm->freqK);
    tr_free(tm->tree);
  }
  if (tm->rate_matrix != NULL) mm_free(tm->rate_matrix);
  if (tm->backgd_freqs != NULL) vec_free(tm->backgd_freqs);
  if (tm->ignore_branch != NULL) sfree(tm->ignore_branch);
  if (tm->in_subtree != NULL) sfree(tm->in_subtree);
  if (tm->param_map != NULL) sfree(tm->param_map);
  if (tm->all_params != NULL) vec_free(tm->all_params);
  if (tm->bound_arg != NULL) {
    for (i=0; i<lst_size(tm->bound_arg); i++) 
      str_free(lst_get_ptr(tm->bound_arg, i));
    lst_free(tm->bound_arg);
  }
  if (tm->noopt_arg != NULL)
    str_free(tm->noopt_arg);
  if (tm->iupac_inv_map != NULL)
    free_iupac_inv_map(tm->iupac_inv_map);
  sfree(tm);
}

/* set up lists that allow each rate matrix parameter to be mapped to
   the rows and columns in which it appears */
void tm_init_rmp(TreeModel *tm) {
  int i, j;
  if (tm->rate_matrix_param_row != NULL) return;
  if (tm->rate_matrix == NULL || tm->subst_mod == UNDEF_MOD || 
      tm->tree == NULL) 
    tm->rate_matrix_param_row = tm->rate_matrix_param_col = NULL;
  else {
    int nparams = tm_get_nparams(tm);
    int nrmparams = tm_get_nratematparams(tm);
    tm->rate_matrix_param_row = (List**)smalloc(nparams * sizeof(List*));
    tm->rate_matrix_param_col = (List**)smalloc(nparams * sizeof(List*));
    for (i = 0; i < nparams; i++) 
      tm->rate_matrix_param_row[i] = tm->rate_matrix_param_col[i] = NULL;
                                /* NULL for non-rate-matrix params;
                                   keeps indexing simple */
    for (i=0; i<nrmparams; i++) {
      tm->rate_matrix_param_row[tm->ratematrix_idx + i] = lst_new_int(2);
      tm->rate_matrix_param_col[tm->ratematrix_idx + i] = lst_new_int(2);
    }

    if (tm->alt_subst_mods != NULL) {
      subst_mod_type tempmod = tm->subst_mod;
      for (j=0; j<lst_size(tm->alt_subst_mods); j++) {
	AltSubstMod *altmod = lst_get_ptr(tm->alt_subst_mods, j);
	tm->subst_mod = altmod->subst_mod;
	nrmparams = tm_get_nratematparams(tm);
	for (i=0; i<nrmparams; i++) {
	  tm->rate_matrix_param_row[altmod->ratematrix_idx+i] = lst_new_int(2);
	  tm->rate_matrix_param_col[altmod->ratematrix_idx+i] = lst_new_int(2);
	}
      }
      tm->subst_mod = tempmod;
    }
  }
}


void tm_free_rmp(TreeModel *tm) {
  int i;
  int nparams = tm_get_nparams(tm);
  if (tm->rate_matrix_param_row == NULL) return;
  for (i = 0; i < nparams; i++) {
    if (tm->rate_matrix_param_row[i] != NULL) {
      lst_free(tm->rate_matrix_param_row[i]);
      lst_free(tm->rate_matrix_param_col[i]);
    }
  }  
  sfree(tm->rate_matrix_param_row);
  sfree(tm->rate_matrix_param_col);
  tm->rate_matrix_param_row = NULL;
  tm->rate_matrix_param_col = NULL;
}


/* read tree model from file, with simple format specifying background
   rates, rate matrix, and tree (topology and branch lengths) */
TreeModel *tm_new_from_file(FILE *f, int discard_likelihood) {
  char tag[STR_MED_LEN], alphabet[MAX_ALPH_SIZE]; 
  String *tmpstr = str_new(STR_LONG_LEN);
  Vector *backgd = NULL, *rate_weights = NULL;
  Matrix *rmat = NULL;
  MarkovMatrix *M = NULL;
  TreeNode *tree = NULL;
  int size = 0, order = 0, nratecats = -1, empty = TRUE, have_likelihood=0;
  double alpha = 0, selection, likelihood;
  TreeModel *retval;
  subst_mod_type subst_mod = UNDEF_MOD;
  int i, j, have_selection=0;
  List *rate_consts = NULL;
  alphabet[0] = '\0';

  while (fscanf(f, "%s", tag) != EOF) {
    if (tag[0] == '#') {
      str_readline(tmpstr, f);
      continue;
    }
    empty = FALSE;
    if (!strcmp(tag, ALPHABET_TAG)) {
      str_readline(tmpstr, f);

      j = 0;
      for (i = 0; i < tmpstr->length; i++) 
        if (!isspace(tmpstr->chars[i])) alphabet[j++] = tmpstr->chars[i];
      alphabet[j] = '\0';
      size = j;
    }
    else if (!strcmp(tag, ORDER_TAG)) {
      str_readline(tmpstr, f);
      if (str_as_int(tmpstr, &order) == 1 || order < 0) {
        die("ERROR: bad ORDER line in tree model file.\n");
      }
      size = int_pow(size, order+1);
    }
    else if (!strcmp(tag, SUBST_MOD_TAG)) {
      str_readline(tmpstr, f);
      str_double_trim(tmpstr);
      subst_mod = tm_get_subst_mod_type(tmpstr->chars); 
    }
    else if (!strcmp(tag, NRATECATS_TAG)) {
      str_readline(tmpstr, f);
      if (str_as_int(tmpstr, &nratecats) == 1 || nratecats < 0) {
        die("ERROR: bad NRATECATS line in tree model file.\n");
      }
    }
    else if (!strcmp(tag, ALPHA_TAG)) {
      str_readline(tmpstr, f);
      if (str_as_dbl(tmpstr, &alpha) == 1 || alpha < 0) {
        die("ERROR: bad ALPHA line in tree model file.\n");
      }
    }
    else if (!strcmp(tag, BACKGROUND_TAG)) {
      if (size == 0) {
        die("ERROR: ALPHABET and SUBST_MOD lines must precede BACKGROUND and RATE_MATRIX in tree model file.\n");
      }
      backgd = vec_new_from_file(f, size);
    }
    else if (!strcmp(tag, RATE_MATRIX_TAG)) {
      if (size == 0) {
        die("ERROR: ALPHABET and SUBST_MOD lines must precede BACKGROUND and RATE_MAT in tree model file.\n");
      }
      rmat = mat_new_from_file(f, size, size);
    }
    else if (!strcmp(tag, TREE_TAG)) {
      str_readline(tmpstr, f);
      str_double_trim(tmpstr);
      if (tmpstr->chars[tmpstr->length-1] == ';') 
	tmpstr->chars[--tmpstr->length] = '\0';
      tree = tr_new_from_string(tmpstr->chars);      
    }
    else if (strcmp(tag, LNL_TAG) == 0) {
      str_readline(tmpstr, f);
      if (!discard_likelihood) {
	if (str_as_dbl(tmpstr, &likelihood) == 1)
	  die("ERROR: bad %s line in tree model file.\n", LNL_TAG);
	have_likelihood = 1;
      }
    }
    else if (!strcmp(tag, RATE_CONSTS_TAG)) {
      Vector *tmpvect;
      if (nratecats < 0) 
        die("ERROR: NRATECATS must precede RATE_CONSTS in tree model file.\n");
      /* easiest to use vec_read and convert */
      tmpvect = vec_new_from_file(f, nratecats);
      rate_consts = lst_new_dbl(nratecats);
      for (i = 0; i < nratecats; i++) 
        lst_push_dbl(rate_consts, vec_get(tmpvect, i));
      vec_free(tmpvect);                     
    }
    else if (!strcmp(tag, RATE_WEIGHTS_TAG)) {
      if (nratecats < 0) 
        die("ERROR: NRATECATS must precede RATE_WEIGHTS in tree model file.\n");
      rate_weights = vec_new_from_file(f, nratecats);
    }
    else if (!strcmp(tag, SELECTION_TAG)) {
      str_readline(tmpstr, f);
      if (str_as_dbl(tmpstr, &selection)==1)
	die("ERROR: bad SELECTION line in tree model file\n");
      have_selection = 1;
    } 
    else if (!strcmp(tag, ALT_MODEL_TAG)) {
      break;
    }
    else {
      die("ERROR: unrecognized tag in model file (\"%s\").\n", 
	  tag);
    }
  }

  if (empty) die("ERROR: empty tree model file.\n");

  if (rmat != NULL) {
    M = mm_new_from_matrix(rmat, alphabet, CONTINUOUS);
  }  else {
    if (size == 0) 
      die ("ERROR: ALPHABET line must precede RATE_MAT in tree model file.");
    M = mm_new(size, alphabet, CONTINUOUS);
  }

  if (nratecats < 0) nratecats = 1;

  retval = tm_new(tree, M, backgd, subst_mod, alphabet, nratecats, alpha, 
                  rate_consts, -1);	 

  if (have_selection) {
    retval->selection_idx = 0;
    retval->selection = selection;
  }

  //this will only be true if discard_likelihood==0 and likelihood was in file
  if (have_likelihood)
    retval->lnL = likelihood;

  if (retval->order != order) 
    die("ERROR: substitution model and order are inconsistent in tree model file.\n");

  /* if rate weights are explicitly defined, set freqK; otherwise
     default weights will be set up by tm_new */
  if (rate_weights != NULL) {
    if (!retval->empirical_rates) 
      die("ERROR: RATE_CONSTS required if RATE_WEIGHTS.\n");
    for (i = 0; i < nratecats; i++) 
      retval->freqK[i] = vec_get(rate_weights, i);
    normalize_probs(retval->freqK, retval->nratecats);
  }

  while (strcmp(tag, ALT_MODEL_TAG)==0) {
    String *altmod_str = str_new(100);
    AltSubstMod *altmod;
    str_readline(altmod_str, f);
    str_double_trim(altmod_str);
    altmod = tm_add_alt_mod(retval, altmod_str);
    while (EOF != fscanf(f, "%s", tag)) {
      if (strcmp(tag, ALT_MODEL_TAG)==0) break;
      if (!strcmp(tag, SUBST_MOD_TAG)) {
	str_readline(tmpstr, f);
	str_double_trim(tmpstr);
	altmod->subst_mod = tm_get_subst_mod_type(tmpstr->chars);
      } else if (!strcmp(tag, BACKGROUND_TAG)) {
	altmod->backgd_freqs = vec_new_from_file(f, size);
	altmod->separate_backgd = 1;
      } else if (!strcmp(tag, RATE_MATRIX_TAG)) {     
	altmod->rate_matrix = 
	  mm_new_from_matrix(mat_new_from_file(f, size, size), 
			     alphabet, CONTINUOUS);
      } else if (!strcmp(tag, SELECTION_TAG)) {
	str_readline(tmpstr, f);
	if (str_as_dbl(tmpstr, &altmod->selection) == 1) 
	  die("ERROR: bad %s line in tree model file\n", SELECTION_TAG);
	altmod->selection_idx = 0;  //will be reset later; -1 implies do not use
      } else if (!strcmp(tag, BGC_TAG)) {
	str_readline(tmpstr, f);
	if (str_as_dbl(tmpstr, &altmod->bgc) == 1) 
	  die("ERROR: bad %s line in tree model file\n", BGC_TAG);
	altmod->bgc_idx = 0;  //will be reset later
      } else die("ERROR: unrecognized tag %s in ALT_SUBST_MODEL section of mod file\n",
		 tag);
    }
  }
  str_free(tmpstr);
  if (rate_consts != NULL) lst_free(rate_consts);
  if (rate_weights != NULL) vec_free(rate_weights);

  return retval;
}


void tm_print_altmodel(FILE *F, AltSubstMod *alt_model, TreeModel *tm) {
  int i;

  fprintf(F, "\n%s %s\n", ALT_MODEL_TAG, alt_model->defString->chars);
  fprintf(F, "%s %s\n", SUBST_MOD_TAG, 
          tm_get_subst_mod_string(alt_model->subst_mod));
  if (alt_model->selection_idx >=0)
    fprintf(F, "%s %f\n", SELECTION_TAG, alt_model->selection);
  if (alt_model->bgc_idx >= 0)
    fprintf(F, "%s %f\n", BGC_TAG, alt_model->bgc);
  if (alt_model->separate_backgd) {
    if (alt_model->backgd_freqs == NULL) 
      die("Error in tm_print_altmodel: altmod->separate_backgd==1 but altmod->backgd_freqs is NULL\n");
    fprintf(F, "%s ", BACKGROUND_TAG);
    for (i = 0; i < alt_model->backgd_freqs->size; i++) 
      fprintf(F, "%f ", vec_get(alt_model->backgd_freqs, i));
    fprintf(F, "\n");
  }

  if (alt_model->rate_matrix != NULL) {
    fprintf(F, "%s\n", RATE_MATRIX_TAG);
    mat_print(alt_model->rate_matrix->matrix, F);
  }
}


void tm_print(FILE *F, TreeModel *tm) {
  int i;
  fprintf(F, "%s ", ALPHABET_TAG);
  for (i = 0; i < strlen(tm->rate_matrix->states); i++) 
    fprintf(F, "%c ", tm->rate_matrix->states[i]);
  fprintf(F, "\n");

  fprintf(F, "%s %d\n", ORDER_TAG, tm->order);

  fprintf(F, "%s %s\n", SUBST_MOD_TAG, 
          tm_get_subst_mod_string(tm->subst_mod));

  if (tm->nratecats > 1) {
    fprintf(F, "%s %d\n", NRATECATS_TAG, tm->nratecats);
    if (tm->empirical_rates) {
      fprintf(F, "%s ", RATE_CONSTS_TAG);
      for (i = 0; i < tm->nratecats; i++) fprintf(F, "%f ", tm->rK[i]);
      fprintf(F, "\n");
      fprintf(F, "%s ", RATE_WEIGHTS_TAG);
      for (i = 0; i < tm->nratecats; i++) fprintf(F, "%f ", tm->freqK[i]);
      fprintf(F, "\n");
    }
    else
      fprintf(F, "%s %f\n", ALPHA_TAG, tm->alpha);
  }

  if (tm->selection_idx >= 0)
    fprintf(F, "%s %f\n", SELECTION_TAG, tm->selection);

  if (tm->lnL != NULL_LOG_LIKELIHOOD)
    fprintf(F, "%s %f\n", LNL_TAG, tm->lnL);

  if (tm->backgd_freqs != NULL) {
    fprintf(F, "%s ", BACKGROUND_TAG);
    for (i = 0; i < tm->backgd_freqs->size; i++) 
      fprintf(F, "%f ", vec_get(tm->backgd_freqs, i));
    fprintf(F, "\n");
  }

  if (tm->rate_matrix != NULL) {
    fprintf(F, "%s\n", RATE_MATRIX_TAG);
    mat_print(tm->rate_matrix->matrix, F);
  }

  if (tm->tree != NULL) {
    fprintf(F, "%s ", TREE_TAG);
    tr_print(F, tm->tree, 1);
  }

  if (tm->alt_subst_mods != NULL) {
    for (i=0; i<lst_size(tm->alt_subst_mods); i++)
      tm_print_altmodel(F, lst_get_ptr(tm->alt_subst_mods, i), tm);
  }
}

/* Note: does not copy msa_seq_idx, tree_posteriors, P, rate_matrix_param_row,
   or iupac_inv_map
 */
TreeModel *tm_create_copy(TreeModel *src) {
  TreeModel *retval;
  Vector *freqs = vec_new(src->backgd_freqs->size);
  int i, j, cat;

  vec_copy(freqs, src->backgd_freqs);
  retval = tm_new(src->tree != NULL ? tr_create_copy(src->tree) : NULL, 
                  mm_create_copy(src->rate_matrix), freqs, 
                  src->subst_mod, NULL, 
                  src->nratecats, src->alpha, NULL, 
                  src->root_leaf_id);
  retval->msa = src->msa;
  retval->lnL = src->lnL;
  retval->use_conditionals = src->use_conditionals;
  retval->category = src->category;
  retval->allow_gaps = src->allow_gaps;
  retval->allow_but_penalize_gaps = src->allow_but_penalize_gaps;
  retval->inform_reqd = src->inform_reqd;
  retval->estimate_backgd = src->estimate_backgd;
  retval->estimate_branchlens = src->estimate_branchlens;
  retval->estimate_ratemat = src->estimate_ratemat;
  retval->scale = src->scale;
  retval->scale_sub = src->scale_sub;
  retval->scale_sub_bound = src->scale_sub_bound;
  retval->selection = src->selection;
  retval->site_model = src->site_model;
  if (src->in_subtree != NULL) {
    retval->in_subtree = smalloc(retval->tree->nnodes * sizeof(int));
    for (i=0; i < retval->tree->nnodes; i++)
      retval->in_subtree[i] = src->in_subtree[i];
  }
  if (src->subtree_root != NULL) {
    for (i=0; i < lst_size(tr_postorder(src->tree)); i++)
      if (lst_get_ptr(tr_postorder(src->tree), i) == src->subtree_root)
	break;
    if (i == lst_size(tr_postorder(src->tree)))
      die("Error finding subtree_root in tm_create_copy\n");
    retval->subtree_root = lst_get_ptr(tr_postorder(retval->tree), i);
  }
  if (src->ignore_branch != NULL) {
    retval->ignore_branch = smalloc(src->tree->nnodes * sizeof(int));
    for (i=0; i < src->tree->nnodes; i++)
      retval->ignore_branch[i] = src->ignore_branch[i];
  }
  
  if (src->empirical_rates) {
    for (i = 0; i < src->nratecats; i++) {
      retval->rK[i] = src->rK[i];
      retval->freqK[i] = src->freqK[i];
    }
    retval->empirical_rates = 1;
  }

  retval->scale_idx = src->scale_idx;
  retval->bl_idx = src->bl_idx;
  retval->ratematrix_idx = src->ratematrix_idx;
  retval->backgd_idx = src->backgd_idx;
  retval->ratevar_idx = src->ratevar_idx;
  retval->selection_idx = src->selection_idx;
  if (src->noopt_arg != NULL)
    retval->noopt_arg = str_new_charstr(src->noopt_arg->chars);
  else retval->noopt_arg = NULL;
  retval->eqfreq_sym = src->eqfreq_sym;
  retval->scale_during_opt = src->scale_during_opt;

  if (src->all_params != NULL) {
    retval->all_params = vec_create_copy(src->all_params);
    if (src->param_map != NULL) {
      retval->param_map = smalloc(src->all_params->size*sizeof(int));
      for (i=0; i<src->all_params->size; i++)
	retval->param_map[i] = src->param_map[i];
    }
    else retval->param_map = NULL;
  }
  if (src->bound_arg != NULL) {
    retval->bound_arg = lst_new_ptr(lst_size(src->bound_arg));
    for (i=0; i < lst_size(src->bound_arg); i++)
      lst_push_ptr(retval->bound_arg, str_new_charstr(((String*)lst_get_ptr(src->bound_arg, i))->chars));
  }


  /* Copy lineage-specific models */
  if (src->alt_subst_mods != NULL) {
    AltSubstMod *currmod, *newmod;
    retval->alt_subst_mods = lst_new_ptr(lst_size(src->alt_subst_mods));
    for (i = 0; i < lst_size(src->alt_subst_mods); i++) {
      currmod = (AltSubstMod*)lst_get_ptr(src->alt_subst_mods, i);
      newmod = tm_new_alt_subst_mod(currmod->subst_mod, NULL, NULL);
      newmod->defString = str_new_charstr(currmod->defString->chars);
      if (currmod->backgd_freqs != NULL)
	newmod->backgd_freqs = vec_create_copy(currmod->backgd_freqs);
      else newmod->backgd_freqs = NULL;
      if (currmod->rate_matrix != NULL)
	newmod->rate_matrix = mm_create_copy(currmod->rate_matrix);
      else newmod->rate_matrix = NULL;
      newmod->ratematrix_idx = currmod->ratematrix_idx;
      newmod->backgd_idx = currmod->backgd_idx;
      newmod->separate_backgd = currmod->separate_backgd;
      newmod->separate_model = currmod->separate_model;
      newmod->selection = currmod->selection;
      newmod->bgc = currmod->bgc;
      newmod->selection_idx = currmod->selection_idx;
      newmod->bgc_idx = currmod->bgc_idx;
      if (currmod->param_list != NULL) {
	String *currstr;
	newmod->param_list = lst_new_ptr(lst_size(currmod->param_list));
	for (j = 0; j < lst_size(currmod->param_list); j++) {
	  currstr = str_new_charstr(((String*)lst_get_ptr(currmod->param_list, j))->chars);
	  lst_push_ptr(newmod->param_list, currstr);
	}
      }
      else newmod->param_list = NULL;
      if (newmod->noopt_arg == NULL)
	currmod->noopt_arg = NULL;
      else currmod->noopt_arg = str_new_charstr(newmod->noopt_arg->chars);
      lst_push_ptr(retval->alt_subst_mods, (void*)newmod);
    }
  }
  else retval->alt_subst_mods = NULL;
  if (src->alt_subst_mods_ptr != NULL) {
    List *traversal;
    TreeNode *n;
    if (retval->tree == NULL)
      die("ERROR tm_create_copy: retval->tree is NULL\n");
    traversal = tr_preorder(retval->tree);
    retval->alt_subst_mods_ptr = smalloc(lst_size(traversal)*sizeof(AltSubstMod**));
    for (i=0; i<lst_size(traversal); i++) {
      n = lst_get_ptr(traversal, i);
      if (src->alt_subst_mods_ptr[n->id] == NULL) {
	retval->alt_subst_mods_ptr[n->id] = NULL;
	continue;
      }
      retval->alt_subst_mods_ptr[n->id] = smalloc(src->nratecats * sizeof(AltSubstMod*));
      for (cat=0; cat < src->nratecats; cat++) {
	if (src->alt_subst_mods_ptr[n->id][cat] == NULL) {
	  retval->alt_subst_mods_ptr[n->id][cat] = NULL;
	  continue;
	}
	/* Need to find the model for this lineage */
	for (j = 0; j<lst_size(src->alt_subst_mods); j++) {
	  if (lst_get_ptr(src->alt_subst_mods, j) == src->alt_subst_mods_ptr[n->id][cat])
	    retval->alt_subst_mods_ptr[n->id][cat] = lst_get_ptr(retval->alt_subst_mods, j);
	  break;
	}
	if (j >= lst_size(src->alt_subst_mods))
	  die("ERROR in tm_create_copy\n");
      }
    }
  } else retval->alt_subst_mods_ptr = NULL;


  /* NOTE: ignoring params, tree_posteriors, etc. */

  return retval;
}


/* add a lineage-specific model.   altmod_string should be in the
 form label:MODNAME:const_params  or label:param1,param2:const_params
 The third field is optional.
  The second and third fields are saved in the AltSubstMod structure to
  be parsed later.  
 If the second field is a model name, an entirely separate subst model 
 will be used for this lineage.  If it is a list of parameters, then same 
 subst model will be used, with these parameters estimated separately. */
AltSubstMod* tm_add_alt_mod(TreeModel *mod, String *altmod_str) {
  AltSubstMod *altmod, *tempmod;
  String *label=NULL, *modstr;
  List *templst, *nodes, *nodelst;
  TreeNode *n=NULL;
  int i, j, k, cat=-1;

  altmod = tm_new_alt_subst_mod(UNDEF_MOD, NULL, NULL);
  altmod->defString = str_new_charstr(altmod_str->chars);
  altmod->separate_backgd = 0;
  altmod->selection_idx = -1;
  altmod->selection = 0.0;
  altmod->bgc = 0.0;
  altmod->bgc_idx = -1;
  templst = lst_new_ptr(3);

  str_split(altmod_str, ":", templst);
  if (lst_size(templst) != 2 && lst_size(templst) != 3) 
    die("ERROR: invalid alt-model argument %s\n", altmod_str->chars);
  nodelst = lst_new_ptr(2);
  str_split(lst_get_ptr(templst, 0), ",", nodelst);
  modstr = (String*)lst_get_ptr(templst, 1);
  if (lst_size(templst)==3) 
    altmod->noopt_arg = (String*)lst_get_ptr(templst, 2);  //this will get parsed later
  else altmod->noopt_arg = NULL;
  str_free(lst_get_ptr(templst, 0));
  lst_free(templst);

  if (mod->alt_subst_mods_ptr ==  NULL) {
    mod->alt_subst_mods_ptr = smalloc(mod->tree->nnodes*sizeof(AltSubstMod**));
    for (i=0; i<mod->tree->nnodes; i++) {
      mod->alt_subst_mods_ptr[i] = smalloc(mod->nratecats * sizeof(AltSubstMod*));
      for (j=0; j < mod->nratecats; j++)
	mod->alt_subst_mods_ptr[i][j] = NULL;
    }
  }
  nodes = lst_new_ptr(10);
  templst = lst_new_ptr(2);
  for (i=0; i < lst_size(nodelst); i++) {
    str_split(lst_get_ptr(nodelst, i), "#", templst);
    cat = -1;
    if (lst_size(templst) == 2) {
      cat = atoi(((String*)lst_get_ptr(templst, 1))->chars);
      if (cat >= 0 && cat < mod->nratecats) 
	label = lst_get_ptr(templst, 0);
      else die("ERROR: category number should be in range [0,%i)\n", mod->nratecats);
    }
    if (cat == -1) 
      label = lst_get_ptr(nodelst, i);
    tr_get_labelled_nodes(mod->tree, label->chars, nodes);
    if (lst_size(nodes) == 0) {
      n = tr_get_node(mod->tree, label->chars);
      if (n != NULL)
	lst_push_ptr(nodes, n);
      else die("ERROR: no nodes have label or name %s\n", label->chars);
    }
    for (j=0;  j< lst_size(nodes); j++) {
      n = lst_get_ptr(nodes, j);
      if (cat == -1)
	for (k=0; k < mod->nratecats; k++)
	  mod->alt_subst_mods_ptr[n->id][k] = altmod;
      else mod->alt_subst_mods_ptr[n->id][cat] = altmod;
    }
  }
  lst_free_strings(templst);
  lst_free(templst);
  lst_free_strings(nodelst);
  lst_free(nodelst);
  lst_free(nodes);

  //add altmod to mod
  if (mod->alt_subst_mods == NULL)
    mod->alt_subst_mods = lst_new_ptr(1);
  lst_push_ptr(mod->alt_subst_mods, altmod);

  //if modstr is a subst mod, then this is a separate model 
  //(optimize all ratematrix params separately)
  // by default we will still keep equilibrium frequencies the same.
  // the only way to estimate those separately is to use init.mod and
  // send them in non-null
  altmod->subst_mod = tm_get_subst_mod_type(modstr->chars);
  altmod->rate_matrix = mm_create_copy(mod->rate_matrix);
  if (mod->selection_idx >= 0 && mod->selection != 0.0)
    tm_unapply_selection_bgc(altmod->rate_matrix, mod->selection, 0.0);
  altmod->backgd_freqs = NULL;
  if (altmod->subst_mod != UNDEF_MOD) {
    altmod->param_list = NULL;
    altmod->separate_model = 1;
  }
  else {
    int j;
    //otherwise it is a list of parameters to be optimized.  Use the 
    //same subst model as main model, but optimize these parameters
    //separately.
    altmod->subst_mod = mod->subst_mod;
    altmod->param_list = lst_new_ptr(10);
    altmod->separate_model = 0;
    
    //since commas are used to separate boundaries and parameters,
    // we need to split by comma and then re-combine places where
    // the split was actually due to boundaries.
    str_split(modstr, ",", altmod->param_list);
    for (i=0; i < lst_size(altmod->param_list); i++) {
      String *s = (String*)lst_get_ptr(altmod->param_list, i);
      if (NULL != (strstr(s->chars, "["))) {
	String *s2 = NULL;
	if (i+1 < lst_size(altmod->param_list))
	  s2 = (String*)lst_get_ptr(altmod->param_list, i+1);
	if (s2 == NULL || 
	    NULL != strstr(s->chars, "]") || 
	    NULL == strstr(s2->chars, "]"))
	  die("Error parsing alt-mod argument %s\n", modstr->chars);
	str_append_char(s, ',');
	str_append_charstr(s, s2->chars);
	str_free(s2);
	lst_delete_idx(altmod->param_list, i+1);
      }
    }
    for (j=0; j<lst_size(altmod->param_list); j++) {
      String *param_name = str_new_charstr(((String*)lst_get_ptr(altmod->param_list, j))->chars);
      int sharemod = -1;
      str_shortest_root(param_name, '[');
      templst = lst_new_ptr(2);
      str_split(param_name, "#", templst);
      if (lst_size(templst) == 2) {
	sharemod = atoi(((String*)lst_get_ptr(templst, 1))->chars);
	if (sharemod >= 1 && sharemod <= lst_size(mod->alt_subst_mods)) {
	  str_free(param_name);
	  param_name = lst_get_ptr(templst, 0);
	  if (str_equals_charstr(param_name, SELECTION_STR)) {
	    altmod->share_sel = lst_get_ptr(mod->alt_subst_mods, sharemod-1);
	    altmod->selection_idx = 0;
	  }
	  else if (str_equals_charstr(param_name, BGC_STR)) {
	    altmod->share_bgc = lst_get_ptr(mod->alt_subst_mods, sharemod-1);
	    altmod->bgc_idx = 0;
	  }
	  else die("sharing parameter %s has not yet been implemented", param_name->chars);
	} else sharemod = -1;
      }
      lst_free_strings(templst);
      lst_free(templst);
      if (sharemod == -1) {
	if (str_equals_charstr(param_name, BACKGD_STR)) 
	  altmod->separate_backgd = 1;
	if (str_equals_charstr(param_name, SELECTION_STR))
	  altmod->selection_idx = 0;
	if (str_equals_charstr(param_name, BGC_STR))
	  altmod->bgc_idx = 0;
	str_free(param_name);
      }
    }
  }
  str_free(modstr);
  
  if (mod->rate_matrix_param_row != NULL) {
    tm_free_rmp(mod);
    tm_init_rmp(mod);
  }
  if (mod->estimate_branchlens == TM_SCALE_ONLY)
    mod->scale_during_opt=1;

  /* Before returning, check all alt models and see if any have been
     cancelled out by this alt-mod  (This can happen if a user attempts
     to define an alt-mod on the command line, when it has already been
     defined in init-mod).  If so, print a message and quit.
   */
  for (i=0; i < lst_size(mod->alt_subst_mods); i++) {
    List *traversal = tr_preorder(mod->tree);
    TreeNode *node;
    int j;
    tempmod = lst_get_ptr(mod->alt_subst_mods, i);
    for (j=0; j < lst_size(traversal); j++) {
      node = lst_get_ptr(traversal, j);
      if (mod->alt_subst_mods_ptr[node->id] == NULL) continue;
      for (k=0; k < mod->nratecats; k++)
	if (mod->alt_subst_mods_ptr[node->id][k] == tempmod) break;
      if (k < mod->nratecats) break;
    }
    if (j == lst_size(traversal))
      die("ERROR: bad alt-mod configuration; some models overwrite others?\n");
  }
  return altmod;
}


void tm_set_subst_matrices(TreeModel *tm) {
  int i, j;
  double scaling_const, curr_scaling_const=1.0, 
    tmp, branch_scale, selection, bgc=0.0;
  Vector *backgd_freqs = tm->backgd_freqs;
  subst_mod_type subst_mod = tm->subst_mod;
  MarkovMatrix *rate_matrix = tm->rate_matrix;
  TreeNode *n;

  scaling_const = -1;

  if (tm->estimate_branchlens != TM_SCALE_ONLY) 
    tm->scale = 1;
                                /* be sure scale factor has an effect
                                   only if estimating scale */

  /* if estimating scale factor for subtree, identify branches in subtree */
  if (tm->estimate_branchlens == TM_SCALE_ONLY && tm->subtree_root != NULL &&
      tm->in_subtree == NULL) 
    tm->in_subtree = tr_in_subtree(tm->tree, tm->subtree_root);

  /* need to compute a matrix scaling constant from the equilibrium
     freqs, in this case (see below) */
  if (subst_mod == F81) {   
    for (i = 0, tmp = 0; i < tm->rate_matrix->size; i++)
      tmp += vec_get(tm->backgd_freqs, i) *
        vec_get(tm->backgd_freqs, i);
    scaling_const = curr_scaling_const = 1.0/(1 - tmp);
  }
  selection = tm->selection;

  for (i = 0; i < tm->tree->nnodes; i++) {
    checkInterrupt();
    branch_scale = tm->scale;
    n = lst_get_ptr(tm->tree->nodes, i);

    if (n->parent == NULL) continue;

    if (tm->estimate_branchlens == TM_SCALE_ONLY && tm->in_subtree != NULL &&
	tm->in_subtree[i])
      branch_scale *= tm->scale_sub;

    for (j=0; j < tm->nratecats; j++) {
      /* special case where subst models differ by branch and/or rate category*/
      if (tm->alt_subst_mods != NULL) {
	if (tm->alt_subst_mods_ptr[n->id][j] != NULL) {
	  AltSubstMod *altmod = tm->alt_subst_mods_ptr[n->id][j];
	  backgd_freqs = altmod->backgd_freqs;
	  if (backgd_freqs==NULL) backgd_freqs = tm->backgd_freqs;
	  subst_mod = altmod->subst_mod;
	  rate_matrix = altmod->rate_matrix;
	  if (rate_matrix==NULL) rate_matrix = tm->rate_matrix;
	  selection = tm->selection + altmod->selection;
	  bgc = altmod->bgc;
	}
	else {
	  backgd_freqs = tm->backgd_freqs;
	  subst_mod = tm->subst_mod;
	  rate_matrix = tm->rate_matrix;
	  selection = tm->selection;
	  bgc = 0.0;
	}
	if (subst_mod == F81 && 
	    backgd_freqs != tm->backgd_freqs) {   /* need branch-specific scale */
	  for (j = 0, tmp = 0; j < rate_matrix->size; j++)
	    tmp += vec_get(backgd_freqs, j) * vec_get(backgd_freqs, j);
	  curr_scaling_const = 1.0/(1 - tmp);
	} else curr_scaling_const = scaling_const;
      }
      
      if (tm->P[i][j] == NULL)
        tm->P[i][j] = mm_new(rate_matrix->size, rate_matrix->states, DISCRETE);
      
      if (tm->ignore_branch != NULL && tm->ignore_branch[i])  
	/* treat as if infinitely long */
        tm_set_probs_independent(tm, tm->P[i][j]);
      
      /* for simple models, full matrix exponentiation is not necessary */
      else if (subst_mod == JC69 && selection==0.0 && bgc == 0.0)
        tm_set_probs_JC69(tm, tm->P[i][j], 
                          n->dparent * branch_scale * tm->rK[j]);
      else if (subst_mod == F81 && selection == 0.0 && bgc == 0.0)
        tm_set_probs_F81(backgd_freqs, tm->P[i][j], curr_scaling_const, 
                         n->dparent * branch_scale * tm->rK[j]);
      
      else {                     /* full matrix exponentiation */
        mm_exp(tm->P[i][j], rate_matrix, 
               n->dparent * branch_scale * tm->rK[j]);
      }
    }
  }
}

/* version of above that can be used with specified branch length and
   prob matrix */
void tm_set_subst_matrix(TreeModel *tm, MarkovMatrix *P, double t) {
  int i;
  double scaling_const = -1, tmp;

  if (tm->alt_subst_mods != NULL)
    die("ERROR tm_set_subst_mtarix: tm->alt_subst_mods is not NULL\n");
  if (tm->estimate_branchlens == TM_SCALE_ONLY)
    die("ERROR tm_set_subst_matrix: estimate_branchlens is TM_SCALE_ONLY\n");
  if (tm->selection != 0.0) 
    die("ERROR tm_set_subst_matrix got selection=%e\n",
	tm->selection);

  /* need to compute a matrix scaling constant from the equilibrium
     freqs, in this case (see below) */
  if (tm->subst_mod == F81) {   
    for (i = 0, tmp = 0; i < tm->rate_matrix->size; i++)
      tmp += vec_get(tm->backgd_freqs, i) * vec_get(tm->backgd_freqs, i);
    scaling_const = 1.0/(1 - tmp);
  }

  /* for simple models, full matrix exponentiation is not necessary */
  if (tm->subst_mod == JC69)
    tm_set_probs_JC69(tm, P, t);
  else if (tm->subst_mod == F81)
    tm_set_probs_F81(tm->backgd_freqs, P, scaling_const, t);
  else 
    mm_exp(P, tm->rate_matrix, t);
}

/* scale evolutionary rate by const factor (affects branch lengths
   only) */
void tm_scale_branchlens(TreeModel *tm, double scale_const, 
			 int reset_subst_mats) {
  if (tm->tree == NULL) return;
  tr_scale(tm->tree, scale_const);
  if (reset_subst_mats) tm_set_subst_matrices(tm);
}


/* Scales the rate matrix, as well as params if params!=NULL, 
   branchlens if scale_blens=1, and
   substitution matrices if reset_subst_matrices=1.  
   Works with lineage-specific models (although this is not necessarily
   the proper way to calculate scale factor!)

   (This is called tm_scale_model to indicate that it scales all 
   components of the tm model- not to be confused with the old function 
   tm_scale, which only scaled branchlengths, and has been re-named to 
   tm_scale_branchlens)

   NOTE: when params!=NULL, scales params in the same ways as tm_scale_params,
   which is to say, not quite right (see note there).
*/
void tm_scale_model(TreeModel *mod, Vector *params, int scale_blens,
		    int reset_subst_matrices) {
  List *traversal=NULL;
  TreeNode *n;
  int i, j, nrmparams;
  double scale;
  if (scale_blens) {
    if (mod->tree == NULL)
      die("ERROR tm_scale_modeln: mod->tree is NULL\n");
    traversal = tr_preorder(mod->tree);
  }
  if (mod->alt_subst_mods != NULL) {
    die("tm_scale_model not implemented for alt_subst_mods.  Should use scale_during_opt=1");

    /*    
    subst_mod_type temp_mod = mod->subst_mod;
    Vector *temp_backgd = mod->backgd_freqs;
    MarkovMatrix *temp_ratemat = mod->rate_matrix;

    for (i=0; i<lst_size(mod->alt_subst_mods); i++) {
      AltSubstMod *altmod = lst_get_ptr(mod->alt_subst_mods, i);
      mod->subst_mod = altmod->subst_mod;
      if (altmod->backgd_freqs != NULL)
	mod->backgd_freqs = altmod->backgd_freqs;
      if (altmod->rate_matrix != NULL)
	mod->rate_matrix = altmod->rate_matrix;
      nrmparams = tm_get_nratematparams(mod);
      scale = tm_scale_rate_matrix(mod);
      
      if (scale_blens) {
	int pos=0;
	for (j=0; j<lst_size(traversal); j++) {
	  n = lst_get_ptr(traversal, j);
	  if (n->parent == NULL) continue;
	  if (mod->alt_subst_mods_node[n->id] == altmod) {
	    n->dparent *= scale;
	    if (params != NULL) 
	      vec_set(params, mod->bl_idx + pos,
		      scale*vec_get(params, mod->bl_idx + pos));
	    pos++;
	  }
	}
      }
      
      if (params != NULL) {
	for (j=0; j<nrmparams; j++)
	  vec_set(params, altmod->ratematrix_idx+j,
		  1.0/scale * vec_get(params, altmod->ratematrix_idx+j));
      }
      mod->subst_mod = temp_mod;
      mod->backgd_freqs = temp_backgd;
      mod->rate_matrix = temp_ratemat;
      }*/
  }

  //now do for main model 
  nrmparams = tm_get_nratematparams(mod);
  scale = tm_scale_rate_matrix(mod);
  if (scale_blens) {
    int pos=0;
    for (j=0; j<lst_size(traversal); j++) {
      n = lst_get_ptr(traversal, j);
      if (n->parent == NULL) continue;
      //      if (mod->alt_subst_mods==NULL ||
      //	  mod->alt_subst_mods_node[n->id]==NULL) {
	n->dparent *= scale;
	if (params != NULL) 
	  vec_set(params, mod->bl_idx + pos, 
		  scale * vec_get(params, mod->bl_idx + pos));
	pos++;
	//      }
    }
  }
  if (params != NULL) {
    for (i=0; i<nrmparams; i++)
      vec_set(params, mod->ratematrix_idx + i, 
	      1.0/scale * vec_get(params, mod->ratematrix_idx + i));
  }

  //reset subst matrices at very end if necessary
  if (reset_subst_matrices) tm_set_subst_matrices(mod);
      
}


void tm_init_backgd(TreeModel *mod, MSA *msa, int cat) {
  if (mod->backgd_freqs == NULL) 
    mod->backgd_freqs = vec_new(mod->rate_matrix->size);
  if (mod->subst_mod == JC69 || mod->subst_mod == K80)
    vec_set_all(mod->backgd_freqs, 1.0/mod->backgd_freqs->size);
  else
    msa_get_base_freqs_tuples(msa, mod->backgd_freqs, mod->order + 1, cat);
 
  //may want to generalize and create a is_symmetric_model function if
  // we ever add other symmetric models...
  if (mod->subst_mod == SSREV) {
    //need to set the freq of A and T equal, and the freq of C and G equal
    //don't assume freq(GC) = 1 - freq(AT) in case this is ever used for
    // a model with gaps
    double freqAT = vec_get(mod->backgd_freqs, msa->inv_alphabet[(int)'A']) +
      vec_get(mod->backgd_freqs, msa->inv_alphabet[(int)'T']);
    double freqGC = vec_get(mod->backgd_freqs, msa->inv_alphabet[(int)'C']) +
      vec_get(mod->backgd_freqs, msa->inv_alphabet[(int)'G']);
    vec_set(mod->backgd_freqs, msa->inv_alphabet[(int)'A'], freqAT/2.0);
    vec_set(mod->backgd_freqs, msa->inv_alphabet[(int)'T'], freqAT/2.0);
    vec_set(mod->backgd_freqs, msa->inv_alphabet[(int)'C'], freqGC/2.0);
    vec_set(mod->backgd_freqs, msa->inv_alphabet[(int)'G'], freqGC/2.0);
  }
}


/* Modifies equilibrium frequency of a model in such a way that
   reversibility is maintained */
void tm_mod_freqs(TreeModel *mod, Vector *newfreqs) {
  int i, j;
  if (!tm_is_reversible(mod))
    die("ERROR: reversible input model required.\n");
  if (mod->order != 0)
    die("ERROR: single nucleotide model required.\n");
  if (strcmp(mod->rate_matrix->states, DEFAULT_ALPHABET) != 0)
    die("ERROR: default nucleotide alphabet required.\n");
  if (mod->alt_subst_mods != NULL)
    die("ERROR: tm_mod_freqs not implemented for lineage-specific models");
  
  for (i = 0; i < 4; i++) {
    double rowsum = 0;
    for (j = 0; j < 4; j++) {
      double newrate;
      if (i == j) continue;
      newrate = mm_get(mod->rate_matrix, i, j) / 
        vec_get(mod->backgd_freqs, j) * vec_get(newfreqs, j);
      mm_set(mod->rate_matrix, i, j, newrate);
      rowsum += newrate;
    }
    mm_set(mod->rate_matrix, i, i, -rowsum);
  }
  for (i=0; i < 4; i++)
    vec_set(mod->backgd_freqs, i, vec_get(newfreqs, i));
  tm_scale_rate_matrix(mod);
}

/* Generates an alignment according to set of Tree Models and a
   Markov matrix defing how to transition among them.  TreeModels must
   appear in same order as the states of the Markov matrix. 
   NOTE: call srandom externally.
   NOTE: only appropriate for order 0 models */
MSA *tm_generate_msa(int ncolumns, 
                     HMM *hmm,  /* if NULL, single tree model assumed */
                     TreeModel **classmods, 
                     int *labels /* if non-NULL, will be used to
                                    record state (model) responsible
                                    for generating each site; pass
                                    NULL if hmm is NULL */
                     ) {

  int i, class, nseqs, col, ntreenodes, idx, ratecat;
  MSA *msa;
  int *nodestate;
  char **names, **seqs;

  int nclasses = hmm == NULL ? 1 : hmm->nstates;
  int order=-1;

  for (i=0; i < nclasses; i++) {
    if (classmods[i]->order != 0 && 
	!subst_mod_is_codon_model(classmods[i]->subst_mod))
      die("tm_generate_msa is not appropriate for models with order > 0\n");
    if (i==0) order = classmods[i]->order;
    else if (order != classmods[i]->order)
      die("tm_generate_msa expects all models to be of same order\n");
  }

  /* obtain number of sequences from tree models; ensure all have same
     number */
  ntreenodes = classmods[0]->tree->nnodes; 

  nseqs = -1;
  for (i = 0; i < nclasses; i++) {
    /* count leaves in tree */
    int num = (classmods[i]->tree->nnodes + 1) / 2;

    if (classmods[i]->nratecats > 1 && !classmods[i]->empirical_rates)
      DiscreteGamma(classmods[i]->freqK, classmods[i]->rK, 
		    classmods[i]->alpha, classmods[i]->alpha,
		    classmods[i]->nratecats, 0);

    if (nseqs == -1) 
      nseqs = num;
    else if (nseqs != num) 
      die("ERROR in tm_generate_msa: model #%d has %d taxa, while a previous model had %d taxa.\n", i+1, num, nseqs);
  }

  /* create new MSA */
  names = (char**)smalloc(nseqs * sizeof(char*));
  seqs = (char**)smalloc(nseqs * sizeof(char*));
  for (i = 0; i < nseqs; i++) {
    seqs[i] = (char*)smalloc((ncolumns*(order+1) + 1) * sizeof(char));
    seqs[i][ncolumns*(order+1)]='\0';
  }
  msa = msa_new(seqs, names, nseqs, ncolumns*(order+1), 
                classmods[0]->rate_matrix->states);

  /* build sequence idx map; only need one for first model */
  /* FIXME: this assumes all tree models have the same topology; may
     want to relax... */
  classmods[0]->msa_seq_idx = smalloc(classmods[0]->tree->nnodes * 
                                      sizeof(int));
  for (i = 0, idx = 0; i < classmods[0]->tree->nnodes; i++) {
    TreeNode *n = lst_get_ptr(classmods[0]->tree->nodes, i);
    if (n->lchild == NULL && n->rchild == NULL) {
      classmods[0]->msa_seq_idx[i] = idx;
      names[idx] = copy_charstr(n->name);
      idx++;
    }
    else classmods[0]->msa_seq_idx[i] = -1;
  }

  /* generate sequences, column by column */
  if (hmm != NULL && hmm->begin_transitions != NULL)
    class = draw_index(hmm->begin_transitions->data, hmm->nstates);
  else
    class = 0;
  nodestate = (int*)smalloc(ntreenodes * sizeof(int));
  for (col = 0; col < ncolumns; col++) {
    List *traversal = tr_preorder(classmods[class]->tree);
    Vector *backgd=NULL;
    MarkovMatrix *rate_matrix=NULL;
    AltSubstMod *altmod=NULL;

    checkInterruptN(col, 1000);
    if (classmods[class]->nratecats > 1)
      ratecat = pv_draw_idx_arr(classmods[class]->freqK, classmods[class]->nratecats);
    else ratecat = 0;
    if (classmods[class]->alt_subst_mods_ptr != NULL) {
      altmod = classmods[class]->alt_subst_mods_ptr[classmods[class]->tree->id][ratecat];
      if (altmod != NULL) {
	backgd = altmod->backgd_freqs;
	rate_matrix = altmod->rate_matrix;
      }
    }
    if (backgd == NULL) {
      backgd = classmods[class]->backgd_freqs;
      if (backgd == NULL)
	die("ERROR tm_generate_msa: model's background frequencies are not assigned\n");
    }
    if (rate_matrix == NULL)
      rate_matrix = classmods[class]->rate_matrix;

    nodestate[classmods[class]->tree->id] = pv_draw_idx(backgd);
    for (i = 0; i < lst_size(traversal); i++) {
      TreeNode *n = lst_get_ptr(traversal, i);
      TreeNode *l = n->lchild;
      TreeNode *r = n->rchild;
      if (!((l == NULL && r == NULL) || (l != NULL && r != NULL)))
	die("ERROR tm_generate_msa: both children should be NULL or neither\n");

      if (l == NULL) 
	get_tuple_str(&msa->seqs[classmods[0]->msa_seq_idx[n->id]][col*(order+1)],
		      nodestate[n->id], order+1, rate_matrix->states);
      else {
        MarkovMatrix *lsubst_mat, *rsubst_mat;
        if (classmods[class]->P[l->id][ratecat] == NULL)
          tm_set_subst_matrices(classmods[class]);
        lsubst_mat = classmods[class]->P[l->id][ratecat];
        rsubst_mat = classmods[class]->P[r->id][ratecat];
	nodestate[l->id] = mm_sample_state(lsubst_mat, nodestate[n->id]);
	nodestate[r->id] = mm_sample_state(rsubst_mat, nodestate[n->id]);
      }
    }
    if (labels != NULL) labels[col] = class;
    if (hmm != NULL)
      class = mm_sample_state(hmm->transition_matrix, class);
  }
  sfree(nodestate);

  return msa;
}

/* Generates a random alignment as above but uses a list of 
   scales and subtree scales to use.  (If subtreeName is NULL
   subtree scales must be 1).  */
MSA *tm_generate_msa_scaleLst(List *nsitesLst, List *scaleLst, 
			      List *subtreeScaleLst,
			      TreeModel *mod, char *subtreeName) {
  double scale, subtreeScale;
  int nsite, ncolumns=0, i, j, k, idx, col, nseqs, cat;
  char **seqs, **names, *newchar;
  MSA *msa;
  TreeNode *subtreeNode=NULL;
  List *traversal = tr_preorder(mod->tree);

  if (subtreeName == NULL) {
    for (i=0; i<lst_size(subtreeScaleLst); i++) {
      subtreeScale = lst_get_dbl(subtreeScaleLst, i);
      if (subtreeScale != 1.0) {
	fprintf(stderr, "Warning: ignoring subtreeScales because subtree not given\n");
	break;
      }
    }
  }
  else {
    subtreeNode = tr_get_node(mod->tree, subtreeName);
    if (subtreeNode == NULL) die("ERROR: no node with name %s\n", subtreeName);
  }
  for (i=0; i<lst_size(nsitesLst); i++) 
    ncolumns += lst_get_int(nsitesLst, i);
  nseqs = (mod->tree->nnodes+1)/2;
  
    /* create new MSA */
  names = (char**)smalloc(nseqs * sizeof(char*));
  seqs = (char**)smalloc(nseqs * sizeof(char*));
  for (i = 0; i < nseqs; i++) 
    seqs[i] = (char*)smalloc((ncolumns + 1) * sizeof(char));
  msa = msa_new(seqs, names, nseqs, ncolumns, 
                mod->rate_matrix->states);
  
  mod->msa_seq_idx = smalloc(mod->tree->nnodes * sizeof(int));
  for (i = 0, idx = 0; i < mod->tree->nnodes; i++) {
    TreeNode *n = (TreeNode*)lst_get_ptr(traversal, i);
    if (n->lchild == NULL && n->rchild == NULL) {
      mod->msa_seq_idx[i] = idx;
      names[idx] = copy_charstr(n->name);
      idx++;
    }
    else mod->msa_seq_idx[i] = -1;
  }

  newchar = (char*)smalloc(mod->tree->nnodes * sizeof(char));
  col=0;
  for (i=0; i<lst_size(nsitesLst); i++) {
    checkInterruptN(i, 10000);
    nsite = lst_get_int(nsitesLst, i);
    scale = lst_get_dbl(scaleLst, i);
    subtreeScale = lst_get_dbl(subtreeScaleLst, i);
    tr_scale(mod->tree, scale);
    if (subtreeName != NULL) 
      tr_scale_subtree(mod->tree, subtreeNode, subtreeScale, 0);
    tm_set_subst_matrices(mod);
    for (j=0; j<nsite; j++) {
      Vector *backgd;
      if (mod->nratecats > 1) 
	cat = pv_draw_idx_arr(mod->freqK, mod->nratecats);
      else cat=0;

      if (mod->alt_subst_mods_ptr != NULL &&
	  mod->alt_subst_mods_ptr[mod->tree->id][cat] != NULL &&
	  mod->alt_subst_mods_ptr[mod->tree->id][cat]->backgd_freqs != NULL)
	backgd = mod->alt_subst_mods_ptr[mod->tree->id][cat]->backgd_freqs;
      else backgd = mod->backgd_freqs;
      if (backgd == NULL)
	die("tm_generate_msa_scaleLst: model's backgrounds are not assigned");
      
      newchar[mod->tree->id] = 
	mm_sample_backgd(mod->rate_matrix->states, backgd);
      
      for (k=0; k<lst_size(traversal); k++) {
	TreeNode *n = (TreeNode*)lst_get_ptr(traversal, k);
	TreeNode *l = n->lchild;
	TreeNode *r = n->rchild;
	if (!( (l==NULL && r==NULL) || (l!=NULL && r!=NULL)))
	  die("ERROR tm_msa_generate_scaleLst: both children should be NULL or neither\n");
	if (l == NULL)
	  msa->seqs[mod->msa_seq_idx[n->id]][col] = newchar[n->id];
	else {
	  newchar[l->id] = mm_sample_char(mod->P[l->id][cat], newchar[n->id]);
	  newchar[r->id] = mm_sample_char(mod->P[r->id][cat], newchar[n->id]);
	}
      }
      col++;
    }
    tr_scale_subtree(mod->tree, subtreeNode, 1.0/subtreeScale, 0);
    tr_scale(mod->tree, 1.0/scale);
  }
  tm_set_subst_matrices(mod);
  sfree(newchar);
  return msa;
}


/* Generates an alignment according to set of Tree Models and a
   Markov matrix defing how to transition among them.  TreeModels must
   appear in same order as the states of the Markov matrix. 
   NOTE: call srandom externally. */
MSA *tm_generate_msa_random_subtree(int ncolumns, TreeModel *mod,
				    TreeModel *subtreeMod, char *subtree,
				    double subtreeSwitchProb) {
  int i, nseqs, col, idx, cat;
  MSA *msa;
  char *newchar;
  char **names, **seqs;
  TreeNode *subtreeNode;
  List *traversal = tr_preorder(mod->tree);
  int *inSubtree;

  subtreeNode = tr_get_node(mod->tree, subtree);
  if (subtreeNode==NULL) {
    die("ERROR: no node with name %s\n", subtree);
  }
  nseqs = (mod->tree->nnodes+1)/2;
  inSubtree = tr_in_subtree(mod->tree, subtreeNode);
  inSubtree[subtreeNode->id] = TRUE;

  /* create new MSA */
  names = (char**)smalloc(nseqs * sizeof(char*));
  seqs = (char**)smalloc(nseqs * sizeof(char*));
  for (i = 0; i < nseqs; i++) 
    seqs[i] = (char*)smalloc((ncolumns + 1) * sizeof(char));
  msa = msa_new(seqs, names, nseqs, ncolumns, 
                mod->rate_matrix->states);

  /* build sequence idx map; only need one for first model */
  mod->msa_seq_idx = smalloc(mod->tree->nnodes * sizeof(int));
  for (i = 0, idx = 0; i < mod->tree->nnodes; i++) {
    TreeNode *n = (TreeNode*)lst_get_ptr(traversal, i);
    if (n->lchild == NULL && n->rchild == NULL) {
      mod->msa_seq_idx[i] = idx;
      names[idx] = copy_charstr(n->name);
      idx++;
    }
    else mod->msa_seq_idx[i] = -1;
  }

  /* generate sequences, column by column */
  newchar = (char*)smalloc(mod->tree->nnodes * sizeof(char));
  for (col = 0; col < ncolumns; col++) {
    Vector *backgd;
    checkInterruptN(col, 10000);
    if (mod->nratecats > 1)
      cat = pv_draw_idx_arr(mod->freqK, mod->nratecats);
    else cat=0;
    if (mod->alt_subst_mods_ptr != NULL &&
	mod->alt_subst_mods_ptr[mod->tree->id][cat] != NULL &&
	mod->alt_subst_mods_ptr[mod->tree->id][cat]->backgd_freqs != NULL)
      backgd = mod->alt_subst_mods_ptr[mod->tree->id][cat]->backgd_freqs;
    else backgd = mod->backgd_freqs;
    
    if (backgd == NULL)
      die("tm_generate_msa_random_subtree: model's background frequencies are not assigned\n");

    newchar[mod->tree->id] = 
      mm_sample_backgd(mod->rate_matrix->states, backgd);
    for (i = 0; i < lst_size(traversal); i++) {
      TreeNode *n = (TreeNode*)lst_get_ptr(traversal, i);
      TreeNode *l = n->lchild;
      TreeNode *r = n->rchild;
      int j, inSub[2];
      TreeModel *lmod, *rmod;
      if (! ((l == NULL && r == NULL) || (l != NULL && r != NULL)))
	die("ERROR tm_generate_msa_random_subtree: both children should be NULL or neither\n");

      if (l == NULL) 
        msa->seqs[mod->msa_seq_idx[n->id]][col] = newchar[n->id];
      else {
        MarkovMatrix *lsubst_mat, *rsubst_mat;
        inSub[0] = inSubtree[l->id];
        inSub[1] = inSubtree[r->id];

	for (j=0; j<2; j++) {
	  if (unif_rand() < subtreeSwitchProb) 
	    inSub[j]=!inSub[j];
	}
	if (inSub[0]) lmod = subtreeMod;
	else lmod = mod;
	if (inSub[1]) rmod = subtreeMod;
	else rmod=mod;
	
	if (lmod->P[l->id][cat]==NULL) {
	  //	  printf("setting subst matcies inSub=%i\n", inSub[0]);
	  tm_set_subst_matrices(lmod);
	}
	if (rmod->P[r->id][cat]==NULL) {
	  //	  printf("setting subst matrices inSub=%i\n", inSub[1]);
	  tm_set_subst_matrices(rmod);
	}
        lsubst_mat = lmod->P[l->id][cat];
        rsubst_mat = rmod->P[r->id][cat];
        newchar[l->id] = mm_sample_char(lsubst_mat, newchar[n->id]);
        newchar[r->id] = mm_sample_char(rsubst_mat, newchar[n->id]);
      }
    }
  }
  sfree(newchar);
  sfree(inSubtree);
  return msa;
}

/*
  Sets *bound[idx,..., idx+len-1] to value indicated in strval.
  if *bound does not exist, allocate length npar and initialize to
  default_bound.
 */
void tm_add_limit(String *strval, Vector *bound, int *param_map, 
		  int idx, int len) {
  double lim;
  int i;
  if (strval == NULL || strval->length == 0) return;
  if (0 != str_as_dbl(strval, &lim))
    die("ERROR: can't parse boundary parsing value %s\n", strval->chars);
  for (i=0; i<len; i++) {
    if (param_map[idx+i] >= 0)
      vec_set(bound, param_map[idx+i], lim);
  }
}


//takes a string in the form a,b  (where a and b may be empty strings) and
//sets lower limit to a (if not empty) and upper limit to b (if not empty)
//for params with indices from [idx,..., idx+len-1].  Allocates lower_bounds
//and upper_bounds if necessary.
void tm_add_bounds(String *limitstr, Vector *lower_bounds, 
		   Vector *upper_bounds,
		   int *param_map, int idx, int len) {
  List *bound_lst;
  String *lb_str=NULL, *ub_str=NULL;
  
  if (idx == -1) {
    phast_warning("could not add bound %s to constant parameter\n",
		  limitstr->chars);
    return;
  }

  bound_lst = lst_new_ptr(2);
  str_split(limitstr, ",", bound_lst);
  if (lst_size(bound_lst) == 1) {
    if (limitstr->chars[0]==',') {
      lb_str = NULL;
      ub_str = lst_get_ptr(bound_lst, 0);
    }
    else {
      ub_str = NULL;
      lb_str = lst_get_ptr(bound_lst, 0);
    }
  }
  else if (lst_size(bound_lst)==2) {
    lb_str = lst_get_ptr(bound_lst, 0);
    ub_str = lst_get_ptr(bound_lst, 1);
  }
  else 
    die("ERROR: problem parsing boundary argument %s\n", limitstr->chars);

  tm_add_limit(lb_str, lower_bounds, param_map, idx, len);
  tm_add_limit(ub_str, upper_bounds, param_map, idx, len);
  if (lb_str != NULL) str_free(lb_str);
  if (ub_str != NULL) str_free(ub_str);
  lst_free(bound_lst);
}


void tm_set_boundaries(Vector *lower_bounds, Vector *upper_bounds,
		       TreeModel *mod) {
 int i, j, k, *flag, nratepar;
  String *boundstr, *paramstr, *limitstr;
  List *boundarg_lst;
  /* most params have lower bound of zero and no upper bound.
     however, in this case we don't want the eq freqs to go to zero */
  if (mod->estimate_backgd) {
    for (i = 0; i < mod->backgd_freqs->size; i++) {
      if (mod->param_map[mod->backgd_idx+i] >= 0)
	vec_set(lower_bounds, mod->param_map[mod->backgd_idx+i], 0.001);
    }
  }
  /* Also do not let rate matrix parameters get too small (this was
     causing some errors diagonalizing the rate matrix, although the
     errors were ultimately due to not enough data)*/
  if (mod->estimate_ratemat) {
    for (i = 0; i < tm_get_nratematparams(mod); i++) {
      if (mod->param_map[mod->ratematrix_idx+i] >= 0) 
	vec_set(lower_bounds, mod->param_map[mod->ratematrix_idx+i], 1.0e-6);
    }
  }

  if (mod->selection_idx >= 0 && mod->param_map[mod->selection_idx] >= 0) {
    vec_set(lower_bounds, mod->param_map[mod->selection_idx], -BGC_SEL_LIMIT);
    vec_set(upper_bounds, mod->param_map[mod->selection_idx], BGC_SEL_LIMIT);
  }

  /* Check eq freqs and rate matrix params in lineage-specific models too */
  if (mod->alt_subst_mods != NULL) {
    subst_mod_type temp_mod = mod->subst_mod;
    for (j=0; j<lst_size(mod->alt_subst_mods); j++) {
      AltSubstMod *altmod = lst_get_ptr(mod->alt_subst_mods, j);
      mod->subst_mod = altmod->subst_mod;
      if (altmod->backgd_freqs != NULL) {
	if (mod->param_map[altmod->backgd_idx] >= 0)
	  for (i=0; i<altmod->backgd_freqs->size; i++)
	    vec_set(lower_bounds, mod->param_map[altmod->backgd_idx+i], 
		    0.001);
      }
      if (altmod->rate_matrix != NULL) {
	for (i=0; i < tm_get_nratematparams(mod); i++) {
	  if (mod->param_map[altmod->ratematrix_idx+i] >= 0)
	    vec_set(lower_bounds, mod->param_map[altmod->ratematrix_idx+i], 1.0e-6);
	}
      }
      /* set default bounds for selection + bgc parameters if they are to be optimized.
	 They are exponentiated so the bounds can't be too big */
      if (altmod->bgc_idx >= 0 && mod->param_map[altmod->bgc_idx] >= 0) {
	vec_set(lower_bounds, mod->param_map[altmod->bgc_idx], -BGC_SEL_LIMIT);
	vec_set(upper_bounds, mod->param_map[altmod->bgc_idx], BGC_SEL_LIMIT);
      }
      if (altmod->selection_idx >= 0 && mod->param_map[altmod->selection_idx] >= 0) {
	vec_set(lower_bounds, mod->param_map[altmod->selection_idx], -BGC_SEL_LIMIT);
	vec_set(upper_bounds, mod->param_map[altmod->selection_idx], BGC_SEL_LIMIT);
      }
    }
    mod->subst_mod = temp_mod;
  }


  /* Also, in this case, we need to bound the scale of the subtree */
  if (mod->estimate_branchlens == TM_SCALE_ONLY && 
      (mod->in_subtree != NULL || mod->subtree_root != NULL) && 
      mod->scale_sub_bound != NB) {
    if (mod->scale_sub_bound == LB && mod->param_map[mod->scale_idx+1] >= 0) 
      vec_set(lower_bounds, mod->param_map[mod->scale_idx+1], 1);
    if (mod->scale_sub_bound == UB && mod->param_map[mod->scale_idx+1] >= 0) {
      vec_set(upper_bounds, mod->param_map[mod->scale_idx+1], 1);
    }
  }

  
  /* The remaining code in this function parses the boundary 
     options passed to --bound and --alt-mod options */
  if (mod->bound_arg != NULL) {
    boundarg_lst = lst_new_ptr(2);
    for (i=0; i<lst_size(mod->bound_arg); i++) {
      boundstr = lst_get_ptr(mod->bound_arg, i);
      str_split(boundstr, "[]", boundarg_lst);
      if (lst_size(boundarg_lst) != 2) 
	die("error parsing --bound argument %s\n", boundstr);
      paramstr = lst_get_ptr(boundarg_lst, 0);
      limitstr = lst_get_ptr(boundarg_lst, 1);
      if (str_equals_nocase_charstr(paramstr, BACKGD_STR)) 
	tm_add_bounds(limitstr, lower_bounds, upper_bounds, mod->param_map,
		      mod->backgd_idx, tm_get_neqfreqparams(mod));
      else if (str_equals_nocase_charstr(paramstr, RATEMAT_STR)) 
	tm_add_bounds(limitstr, lower_bounds, upper_bounds, mod->param_map,
		      mod->ratematrix_idx, tm_get_nratematparams(mod));
      else if (str_equals_nocase_charstr(paramstr, RATEVAR_STR))
	tm_add_bounds(limitstr, lower_bounds, upper_bounds, mod->param_map,
		      mod->ratevar_idx, tm_get_nratevarparams(mod));
      else if (str_equals_nocase_charstr(paramstr, BRANCHES_STR)) {
	tm_add_bounds(limitstr, lower_bounds, upper_bounds, mod->param_map,
		      mod->bl_idx, tm_get_nbranchlenparams(mod));
	mod->scale_during_opt = 1;
      }
      else if (str_equals_nocase_charstr(paramstr, SCALE_STR)) {
	tm_add_bounds(limitstr, lower_bounds, upper_bounds, mod->param_map,
		      mod->scale_idx, 1);
	mod->scale_during_opt = 1;
      }
      else if (str_equals_nocase_charstr(paramstr, SCALE_SUB_STR)) {
	tm_add_bounds(limitstr, lower_bounds, upper_bounds, mod->param_map,
		      mod->scale_idx+1, 1);
	mod->scale_during_opt = 1;
      }
      else if (str_equals_nocase_charstr(paramstr, SELECTION_STR)) {
	tm_add_bounds(limitstr, lower_bounds, upper_bounds, mod->param_map,
		      mod->selection_idx, 1);
      }
      else {  //if not match any of the above, must be model-specific
	nratepar = tm_get_nratematparams(mod);
	flag = smalloc(nratepar*sizeof(int));
	for (j=0; j<nratepar; j++) flag[j]=0;
	if (0 == tm_flag_subst_param_pos(mod, flag, paramstr)) 
	  die("ERROR: couldn't parse --bound argument %s\n", boundstr);
	for (j=0; j<nratepar; j++)
	  if (flag[j])
	    tm_add_bounds(limitstr, lower_bounds, upper_bounds, 
			  mod->param_map,
			  mod->ratematrix_idx+j, 1);
	sfree(flag);
      }
      str_free(paramstr);
      str_free(limitstr);
    }
    lst_free(boundarg_lst);
  }

  //now parse through boundary arguments in alternative models
  if (mod->alt_subst_mods != NULL) {
    for (j=0; j<lst_size(mod->alt_subst_mods); j++) {
      AltSubstMod *altmod = lst_get_ptr(mod->alt_subst_mods, j);
      if (altmod->param_list != NULL) {
	subst_mod_type temp_subst_mod = mod->subst_mod;
	mod->subst_mod = altmod->subst_mod;
	for (i=0; i<lst_size(altmod->param_list); i++) {
	  boundstr = lst_get_ptr(altmod->param_list, i);
	  for (k=0; k<boundstr->length; k++)
	    if (boundstr->chars[k]=='[') break;
	  if (k==boundstr->length) continue;
	  for (; k < boundstr->length; k++)
	    if (boundstr->chars[k]==']') break;
	  if (k==boundstr->length) 
	    die("unbalacned bracketes in --alt-mod argument %s\n", boundstr);
	  boundarg_lst = lst_new_ptr(2);
	  str_split(boundstr, "[]", boundarg_lst);
	  if (lst_size(boundarg_lst) != 2) 
	    die("error parsing --alt-mod argument %s\n", boundstr->chars);
	  paramstr = lst_get_ptr(boundarg_lst, 0);
	  limitstr = lst_get_ptr(boundarg_lst, 1);
	  if (str_equals_nocase_charstr(paramstr, BACKGD_STR)) 
	    tm_add_bounds(limitstr, lower_bounds, upper_bounds, mod->param_map,
			  altmod->backgd_idx, tm_get_neqfreqparams(mod));
	  else if (str_equals_nocase_charstr(paramstr, RATEMAT_STR)) 
	    tm_add_bounds(limitstr, lower_bounds, upper_bounds, mod->param_map,
			  altmod->ratematrix_idx, 
			  tm_get_nratematparams(mod));
	  else if (str_equals_nocase_charstr(paramstr, SELECTION_STR))
	    tm_add_bounds(limitstr, lower_bounds, upper_bounds, mod->param_map,
			  altmod->selection_idx, 1);
	  else if (str_equals_nocase_charstr(paramstr, BGC_STR))
	    tm_add_bounds(limitstr, lower_bounds, upper_bounds, mod->param_map,
			  altmod->bgc_idx, 1);
	  else {  //if not match any of the above, must be model-specific
	    nratepar = tm_get_nratematparams(mod);
	    flag = smalloc(nratepar*sizeof(int));
	    for (k=0; k<nratepar; k++) flag[k]=0;
	    if (0 == tm_flag_subst_param_pos(mod, flag, paramstr)) 
	      die("ERROR: couldn't parse --bound argument %s\n", boundstr);
	    for (k=0; k<nratepar; k++)
	      if (flag[k])
		tm_add_bounds(limitstr, lower_bounds, upper_bounds, 
			      mod->param_map,
			      altmod->ratematrix_idx+k, 1);
	    sfree(flag);
	  }
	  str_free(paramstr);
	  str_free(limitstr);
	  lst_free(boundarg_lst);
	}
	mod->subst_mod = temp_subst_mod;
      }
    }
  }
}


/* Assumes *lower_bounds and *upper_bounds have not been allocated.
   Also assumes tm_setup_params has already been called.
   Sets each to NULL if no boundaries are needed */
void tm_new_boundaries(Vector **lower_bounds, Vector **upper_bounds,
		       int npar, TreeModel *mod, int allocate_default) {
  int i;


  /* most params have lower bound of zero and no upper bound */
  *lower_bounds = vec_new(npar);
  vec_zero(*lower_bounds);  /* default lower bounds=0 != -INFTY so we always allocate and keep this */
  *upper_bounds = vec_new(npar);
  vec_set_all(*upper_bounds, INFTY);

  tm_set_boundaries(*lower_bounds, *upper_bounds, mod);
  if (allocate_default == 0) {
    for (i=0; i < npar; i++)
      if (vec_get(*upper_bounds, i) != INFTY) break;
    if (i ==  npar) {
      vec_free(*upper_bounds);
      *upper_bounds = NULL;
    }
  }
}
	
	       
//makes sure lower bounds are lower than upper bounds,
//and that opt_param values are between lower and upper bounds.  If not,
//adjusts opt_param to closest boundary and prints warning (sometimes
//this will ruin reversibility).
void tm_check_boundaries(Vector *opt_params, Vector *lower_bounds, 
			 Vector *upper_bounds) {
  int i;
  //check that parameters are within boundaries
  if (!(lower_bounds == NULL || lower_bounds->size == opt_params->size))
    die("ERROR tm_check_boundaries: bad dimensions of lower_bounds\n");
  if (!(upper_bounds == NULL || upper_bounds->size == opt_params->size))
    die("ERROR tm_check_boundaries: bad dimensions of upper_bounds\n");
  for (i=0; i<opt_params->size; i++) {
    if (lower_bounds != NULL && upper_bounds != NULL)
      if (vec_get(lower_bounds, i) > vec_get(upper_bounds, i)) 
	die("ERROR: lower bounds are higher than upper bounds!\n");
    if (lower_bounds != NULL && 
	vec_get(opt_params, i) < vec_get(lower_bounds, i)) {
      vec_set(opt_params, i, vec_get(lower_bounds, i));
      fprintf(stderr, "Warning: had to adjust initial value of parameter %i to stay above lower bound %f\n", i, vec_get(lower_bounds, i));
    }
    if (upper_bounds != NULL &&
	vec_get(opt_params, i) > vec_get(upper_bounds, i)) {
      vec_set(opt_params, i, vec_get(upper_bounds, i));
      fprintf(stderr, "Warning: had to adjust initial value of parameter %i to stay below upper bound %f\n", i, vec_get(upper_bounds, i));
    }
  }
}


/* Given an MSA, a tree topology, and a substitution model, fit a tree
   model using a multidimensional optimization algorithm (BFGS).
   TreeModel 'mod' must already be allocated, and initialized with
   desired tree topology, substitution model, and (if appropriate)
   background frequencies.  The vector 'params' should define the
   initial values for the optimization procedure.  Fuction returns 0
   on success, 1 on failure.  */  
int tm_fit(TreeModel *mod, MSA *msa, Vector *params, int cat, 
           opt_precision_type precision, FILE *logf, int quiet,
	   FILE *error_file) {
  double ll;
  Vector *lower_bounds, *upper_bounds, *opt_params;
  int i, retval = 0, npar, numeval;

  if (msa->ss == NULL) {
    if (msa->seqs == NULL)
      die("ERROR tm_fit: msa->ss and msa->seqs are both NULL\n");
    ss_from_msas(msa, mod->order+1, 0, NULL, NULL, NULL, -1, 
		 subst_mod_is_codon_model(mod->subst_mod));
  }

  if (mod->backgd_freqs == NULL)  {
    tm_init_backgd(mod, msa, cat);
    for (i=0; i<mod->backgd_freqs->size; i++)
      vec_set(params, mod->backgd_idx+i, vec_get(mod->backgd_freqs, i));
  }
  if (mod->alt_subst_mods != NULL) {
    AltSubstMod *altmod;
    for (i=0; i < lst_size(mod->alt_subst_mods); i++) {
      altmod = lst_get_ptr(mod->alt_subst_mods, i);
      if (altmod->rate_matrix == NULL)
	altmod->rate_matrix = mm_create_copy(mod->rate_matrix);
      if (altmod->separate_backgd && altmod->backgd_freqs == NULL)
	altmod->backgd_freqs = vec_create_copy(mod->backgd_freqs);
    }
  }

  if (mod->tree == NULL) {      /* weight matrix */
    mod->lnL = tl_compute_log_likelihood(mod, msa, NULL, NULL, cat, NULL) * 
      log(2);
    return 0;
  }

  mod->msa = msa;               /* package with mod any data needed to
                                   compute likelihoods */
  mod->category = cat;

  npar=0;
  for (i=0; i<params->size; i++) {
    vec_set(mod->all_params, i, vec_get(params, i));
    if (mod->param_map[i] >= npar)
      npar = mod->param_map[i]+1;
  }
  if (npar <= 0)
    die("ERROR tm_fit npar=%i.  Nothing to optimize!\n", npar);
  opt_params = vec_new(npar);
  for (i=0; i<params->size; i++)
    if (mod->param_map[i] >=0)
      vec_set(opt_params, mod->param_map[i], vec_get(params, i));
  
  tm_new_boundaries(&lower_bounds, &upper_bounds, npar, mod, 0);
  tm_check_boundaries(opt_params, lower_bounds, upper_bounds);
  if (mod->estimate_branchlens == TM_BRANCHLENS_NONE ||
      mod->alt_subst_mods != NULL ||
      mod->selection_idx >= 0)
    mod->scale_during_opt = 1;
  if (mod->estimate_branchlens == TM_BRANCHLENS_ALL) {
    for (i=0; i < mod->tree->nnodes; i++) {
      TreeNode *n = lst_get_ptr(mod->tree->nodes, i);
      if (n != mod->tree && n->hold_constant)
	mod->scale_during_opt = 1;
    }
  }
  
  if (!quiet) fprintf(stderr, "numpar = %i\n", opt_params->size);
  retval = opt_bfgs(tm_likelihood_wrapper, opt_params, (void*)mod, &ll, 
                    lower_bounds, upper_bounds, logf, NULL, precision, 
		    NULL, &numeval);

  mod->lnL = ll * -1 * log(2);  /* make negative again and convert to
                                   natural log scale */
  if (!quiet) fprintf(stderr, "Done.  log(likelihood) = %f numeval=%i\n", mod->lnL, numeval);
  tm_unpack_params(mod, opt_params, -1);
  vec_copy(params, mod->all_params);
  vec_free(opt_params);

  if (error_file != NULL)
    tm_variance(error_file, mod, msa, mod->all_params, cat);

  if (mod->scale_during_opt == 0 && 
      mod->subst_mod != JC69 && mod->subst_mod != F81)
                                /* in this case, need to scale final
                                   model (JC69 and F81 are exceptions,
                                   because probability subst. matrices
                                   are not derived from the rate
                                   matrix) */
    tm_scale_model(mod, params, 1, 0);

  if (mod->estimate_branchlens == TM_SCALE_ONLY) { 
                                /* also, do final scaling of tree if
                                   estimating scale only */
    tm_scale_branchlens(mod, mod->scale, 0);
    mod->scale = 1;
    if (mod->subtree_root != NULL) {  /* estimating subtree scale */
      tr_scale_subtree(mod->tree, mod->subtree_root, mod->scale_sub, 1);
      mod->scale_sub = 1;
    } else if (mod->in_subtree != NULL) { /* internal branch scale */
      TreeNode *n;
      for (i=0; i<mod->tree->nnodes; i++)
	if (mod->in_subtree[i]) {
	  n = lst_get_ptr(mod->tree->nodes, i);
	  n->dparent *= mod->scale_sub;
	}
      mod->scale_sub = 1;
    }
  }
  
  if (lower_bounds != NULL) vec_free(lower_bounds);
  if (upper_bounds != NULL) vec_free(upper_bounds);

  if (retval != 0) 
    fprintf(stderr, "WARNING: BFGS algorithm reached its maximum number of iterations.\n");

  return retval;
}


/* Fit several tree model objects simultaneously (parameters may be shared between them).
   msa should be an array of MSA's of length nmod, 
    OR a single msa with a number of categories = nmod, in which case each category
    will be used for each mod.
 */
int tm_fit_multi(TreeModel **mod, int nmod, MSA **msa, int nmsa,
		 opt_precision_type precision, FILE *logf, int quiet) {
  /* thoughts: what is params?  Probably the vector of parameters to optimize.  Need
     to also send in lower and upper, in that case.  Is there any way to flexibly
     indicate which parameters we want to share, or should we just assume this has been
     done before the function is called?

     Possibly share: backgd, rate matrix params (possibly only certain ones)?
     branch lengths, tree scale, selection, alt model parameters...

     Or maybe it makes more sense to say "optimize these trees using all parameters
     the same except the following".  For us, the only different one is bgc, and bgc weight, and bgc
     is not even used in the non-bgc model.  So when we go to unpack it, it should just work...

*/
  double ll;
  Vector *lower_bounds, *upper_bounds, *opt_params;
  int i, j, retval = 0, npar, nstate, numeval;
  List *modlist;

  if (nmod != nmsa) {
    if (nmsa != 1) die("tm_fit_multi: expected one msa or one msa for each mod\n");
    if ((msa[0]->categories == NULL && (msa[0]->ss==NULL || msa[0]->ss->cat_counts == NULL)) ||
	(msa[0]->ncats != nmod))
      die("tm_fit_multi: if only one msa given, should be split into categories for each mod\n");
    
  }

  for (i=0; i < nmsa; i++) {
    if (msa[i]->ss == NULL) {
      if (msa[i]->seqs == NULL)
	die("ERROR tm_fit_multi: msa[%i] has ss and seqs are both NULL\n", i);
      ss_from_msas(msa[i], mod[i]->order+1, 0, NULL, NULL, NULL, -1, 
		   subst_mod_is_codon_model(mod[i]->subst_mod));
    }
  }
  nstate = int_pow((int)strlen(msa[0]->alphabet), mod[0]->order+1);

  for (j=0; j < nmod; j++) {
    if (mod[j]->tree == NULL) die("ERROR tm_fit_multi: no tree in mod %i\n", j);
    /* package with mod any data needed to
       compute likelihoods */
    mod[j]->msa = (nmod == nmsa ? msa[j] : msa[0]);
    mod[j]->category = (nmod == nmsa ? -1 : j);
    if (mod[j]->backgd_freqs == NULL) { 
      mod[j]->backgd_freqs = vec_new(nstate);
      if (mod[j]->subst_mod == JC69 || mod[j]->subst_mod == K80)
	vec_set_all(mod[j]->backgd_freqs, 1.0/mod[j]->backgd_freqs->size);
      else
	msa_get_base_freqs_tuples(mod[j]->msa, 
				  mod[j]->backgd_freqs, mod[j]->order + 1, 
				  mod[j]->category);
      for (i=0; i<mod[j]->backgd_freqs->size; i++)
	vec_set(mod[j]->all_params, mod[j]->backgd_idx+i, vec_get(mod[j]->backgd_freqs, i));
    }
    if (mod[j]->alt_subst_mods != NULL) {
      AltSubstMod *altmod;
      for (i=0; i < lst_size(mod[j]->alt_subst_mods); i++) {
	altmod = lst_get_ptr(mod[j]->alt_subst_mods, i);
	if (altmod->rate_matrix == NULL)
	  altmod->rate_matrix = mm_create_copy(mod[j]->rate_matrix);
	if (altmod->separate_backgd && altmod->backgd_freqs == NULL)
	  altmod->backgd_freqs = vec_create_copy(mod[j]->backgd_freqs);
      }
    }
  }

  npar=0;
  for (j=0; j < nmod; j++) {
    for (i=0; i < mod[j]->all_params->size; i++) {
      if (mod[j]->param_map[i] >= npar)
	npar = mod[j]->param_map[i]+1;
    }
  }
  if (npar <= 0)
    die("ERROR tm_fit npar=%i.  Nothing to optimize!\n", npar);
  opt_params = vec_new(npar);
  for (j=0; j < nmod; j++) {
    for (i=0; i<mod[j]->all_params->size; i++)
      if (mod[j]->param_map[i] >=0)
	vec_set(opt_params, mod[j]->param_map[i], vec_get(mod[j]->all_params, i));
  }
  tm_new_boundaries(&lower_bounds, &upper_bounds, npar, mod[0], 1);
  for (j=1; j < nmod; j++)
    tm_set_boundaries(lower_bounds, upper_bounds, mod[j]);
  tm_check_boundaries(opt_params, lower_bounds, upper_bounds);
  //always scale during opt when optimizing multiple models at once; otherwise
  // it is problematic if models are sharing scale or rate matrix parameters
  for (i=0; i < nmod; i++)
    mod[i]->scale_during_opt = 1;
  
  if (!quiet) fprintf(stderr, "numpar = %i\n", opt_params->size);
  modlist = lst_new_ptr(nmod);
  for (i=0; i < nmod; i++) lst_push_ptr(modlist, mod[i]);
  retval = opt_bfgs(tm_multi_likelihood_wrapper, opt_params, (void*)modlist, 
		    &ll, lower_bounds, upper_bounds, logf, NULL, precision, 
		    NULL, &numeval);
  lst_free(modlist);

  for (j=0; j < nmod; j++)
    mod[j]->lnL = tm_likelihood_wrapper(opt_params, mod[j]) * -1.0 * log(2);
  ll *= -1.0*log(2);

  if (!quiet) {
    fprintf(stderr, "Done.  log(likelihood) = %f numeval=%i (", ll, numeval);
    for (i=0; i < npar; i++) {
      if (i != 0) fprintf(stderr, ", ");
      fprintf(stderr, "%g", vec_get(opt_params, i));
    }
    fprintf(stderr, ")\n");
  }

  vec_free(opt_params);

  vec_free(lower_bounds);
  vec_free(upper_bounds);

  if (retval != 0) 
    fprintf(stderr, "WARNING: BFGS algorithm reached its maximum number of iterations.\n");

  return retval;
}


int void_str_equals_charstr(void *strptr, void *charptr) {
  return str_equals_charstr(*((String**)strptr),
			    (char*)charptr);
}


/* tm_setup_params: assigns parameter indices to mod->scale_idx,
   mod->bl_idx, mod->ratevar_idx, mod->ratematrix_idx which point
   to indices in mod->all_params where corresponding parameters are
   stored.  (as well as pointers in altmod structures).
   
   Then, it determines which parameters are to be optimized, and allocates
   and assigns values to mod->param_map, which maps indices in all_params
   to indices in the optimization vector, so that param_map[i]=j implies
   that all_params[i] is stored in opt_vec[j].  Only parameters which
   are to be optimized are stored in the optimization vector.  Parameters
   which are held constant have param_map[i]=-1.   
 */
int tm_setup_params(TreeModel *mod, int offset) {
  int i, opt_idx = 0, 
    next_idx=offset, pos=0, numpar, *flag=NULL, size;
  List *noopt=NULL;
  subst_mod_type tempmod;
  int j;
  AltSubstMod *altmod;
  int *noopt_flag, noopt_backgd, noopt_selection, noopt_bgc;
  int *use_main;

  //first assign indices in mod->all_params to give position of each
  //type of parameter
  mod->scale_idx = next_idx;  //keep room for scale and subtree_scale
  mod->bl_idx = next_idx + 2;
  if (mod->tree == NULL)
    die("ERROR tm_setup_params: mod->tree is NULL\n");
  size = mod->rate_matrix->size;

  if (mod->estimate_branchlens == TM_BRANCHLENS_CLOCK) {
    /* in this case the number of BL pars is numspec-1, 
       = (numnodes+1)/2-1 = (numnodes-1)/2 */
    mod->backgd_idx = mod->bl_idx + (mod->tree->nnodes-1)/2;
  }
  else
    mod->backgd_idx = mod->bl_idx + mod->tree->nnodes - 1;

  next_idx =  mod->backgd_idx + size;

  if (mod->nratecats > 1) {
    mod->ratevar_idx = next_idx;
    next_idx += tm_get_nratevarparams(mod);
  } 
  else mod->ratevar_idx = -1;
  
  if (mod->selection_idx >= 0)
    mod->selection_idx = next_idx++;

  mod->ratematrix_idx = next_idx;
  next_idx += tm_get_nratematparams(mod);

  if (mod->alt_subst_mods != NULL) {
    AltSubstMod *altmod;
    subst_mod_type tempmod = mod->subst_mod;
    for (i = 0; i<lst_size(mod->alt_subst_mods); i++) {
      altmod = lst_get_ptr(mod->alt_subst_mods, i);
      mod->subst_mod = altmod->subst_mod;
      altmod->backgd_idx = next_idx;
      next_idx += size;
      altmod->ratematrix_idx = next_idx;
      next_idx += tm_get_nratematparams(mod);
      if (altmod->selection_idx >= 0)
	altmod->selection_idx = next_idx++;
      if (altmod->bgc_idx >= 0)
	altmod->bgc_idx = next_idx++;
    }
    mod->subst_mod = tempmod;
  }

  //now, allocate all_params and param_map if necessary
  if (mod->all_params != NULL && mod->all_params->size != next_idx) {
    vec_free(mod->all_params);
    mod->all_params = NULL;
    if (mod->param_map != NULL) {
      sfree(mod->param_map);
      mod->param_map = NULL;
    }
  }
  if (mod->all_params == NULL) 
    mod->all_params = vec_new(next_idx);
  if (mod->param_map == NULL)
    mod->param_map = smalloc(next_idx*sizeof(int));

  //now assign positions in param_map so that
  //param_map[i] >= 0 if this parameter is optimized
  //param_map[i] = -1 if this parameter is held constant
  for (i=0; i<next_idx; i++)
    mod->param_map[i] = -1;

  if (mod->noopt_arg != NULL) {
    noopt = lst_new_ptr(3);
    str_split(mod->noopt_arg, ",", noopt);
    pos = lst_find_compare(noopt, BRANCHES_STR, void_str_equals_charstr);
    if (pos >= 0) {
      //      printf("holding branches const\n");
      mod->estimate_branchlens = TM_BRANCHLENS_NONE;
      str_free(lst_get_ptr(noopt, pos));
      lst_delete_idx(noopt, pos);
    }
    pos = lst_find_compare(noopt, BACKGD_STR, void_str_equals_charstr);
    if (pos >= 0) {
      //      printf("holding backgd const\n");
      mod->estimate_backgd = 0;
      str_free(lst_get_ptr(noopt, pos));
      lst_delete_idx(noopt, pos);
    }
    pos = lst_find_compare(noopt, RATEMAT_STR, void_str_equals_charstr);
    if (pos >= 0) {
      //      printf("holding ratematrix const\n");
      mod->estimate_ratemat = 0;
      str_free(lst_get_ptr(noopt, pos));
      lst_delete_idx(noopt, pos);
    }
  }
  
  pos = -1;
  if (noopt != NULL) 
    pos = lst_find_compare(noopt, SELECTION_STR, void_str_equals_charstr);
  if (pos >= 0) {
    str_free(lst_get_ptr(noopt, pos));
    lst_delete_idx(noopt, pos);
    if (mod->selection_idx < 0) 
      die("ERROR: Cannot hold selection constant; no selection in model\n");
  } else if (mod->selection_idx >= 0)
    mod->param_map[mod->selection_idx] = opt_idx++;

  //first do scale/branchlength params
  pos = -1;
  if (mod->estimate_branchlens == TM_SCALE_ONLY) {
    if (noopt != NULL)
      pos = lst_find_compare(noopt, SCALE_STR, void_str_equals_charstr);
    if (pos >= 0) {
      str_free(lst_get_ptr(noopt, pos));
      lst_delete_idx(noopt, pos);
    }
    else mod->param_map[mod->scale_idx] = opt_idx++;
    if (mod->subtree_root != NULL || mod->in_subtree != NULL) {
      if (noopt != NULL)
	pos = lst_find_compare(noopt, SCALE_SUB_STR, void_str_equals_charstr);
      if (pos >= 0) {
	str_free(lst_get_ptr(noopt, pos));
	lst_delete_idx(noopt, pos);
      }
      else mod->param_map[mod->scale_idx+1] = opt_idx++;
    }
  }
  else if (mod->estimate_branchlens == TM_BRANCHLENS_ALL) {
    List *traversal = tr_preorder(mod->tree);
    int node_idx, root_idx = -1, temp_idx=0;
    int isreversible = tm_is_reversible(mod);
    TreeNode *n;
    for (node_idx=0; node_idx < lst_size(traversal); node_idx++) {
      n = lst_get_ptr(traversal, node_idx);
      if (n->parent == NULL) continue;  //skip root
      if (mod->root_leaf_id == n->id || n->hold_constant) {
	temp_idx++;
	continue;  //don't optimize
      }
      if ((n == mod->tree->lchild || n == mod->tree->rchild) &&
	  isreversible) {
	if (root_idx == -1) root_idx = opt_idx++;
	mod->param_map[mod->bl_idx + temp_idx++] = root_idx;
      }
      else mod->param_map[mod->bl_idx + temp_idx++] = opt_idx++;
    }
  } else if (mod->estimate_branchlens == TM_BRANCHLENS_CLOCK) {
    int numspec = (mod->tree->nnodes+1)/2;
    for (i=0; i<numspec-1; i++) {
      mod->param_map[mod->bl_idx + i] = opt_idx++;
    }
  }
  //else TM_BRANCHLENS_NONE: keep everything at -1

  if (mod->estimate_backgd) {
    if (mod->eqfreq_sym==1) {
      int atpos=-1, gcpos=-1;
      char c;
      if (mod->order != 0)
	die("ERROR tm_setup_params eqfreq_sym==1 mod->order=%i\n", mod->order);
      for (i=0; i<size; i++) {
	c = (char)tolower(mod->rate_matrix->states[i]);
	switch (c) {
	case 'g':
	case 'c':
	  if (gcpos == -1) gcpos = opt_idx++;
	  pos = gcpos;
	  break;
	case 'a':
	case 't':
	  if (atpos == -1) atpos = opt_idx++;
	  pos = atpos;
	  break;
	case '-':
	  pos = opt_idx++;
	  break;
	default:
	  die("ERROR: eqfreq_sym only defined for ACGT alphabet right now (got %c)\n", mod->rate_matrix->states[i]);
	}
	mod->param_map[mod->backgd_idx+i] = pos;
      }
    }
    else {
      for (i=0; i<size; i++)
	mod->param_map[mod->backgd_idx+i] = opt_idx++;
    }
  }

  if (mod->nratecats > 1) {
    int est_rates = (noopt==NULL);
    if (noopt != NULL) {
      pos = lst_find_compare(noopt, RATEVAR_STR, void_str_equals_charstr);
      if (pos >= 0) {
	//	printf("holding ratevar const\n");
	est_rates = 0;
	str_free(lst_get_ptr(noopt, pos));
	lst_delete_idx(noopt, pos);
      } else est_rates = 1;
    }
    if (est_rates) {
      for (i=0; i < tm_get_nratevarparams(mod); i++)
	  mod->param_map[mod->ratevar_idx+i] = opt_idx++;
    }
  }
  
  numpar = tm_get_nratematparams(mod);
  if (numpar > 0) 
    flag = smalloc(numpar*sizeof(int));
  for (i=0; i<numpar; i++) flag[i]=0;
  if (noopt != NULL) {
    for (i=0; i<lst_size(noopt); i++) {
      if (0 == tm_flag_subst_param_pos(mod, flag, lst_get_ptr(noopt, i))) 
	die("ERROR: couldn't parse parameter name %s from no-opt argument for model %s\n", ((String*)lst_get_ptr(noopt, i))->chars, tm_get_subst_mod_string(mod->subst_mod));
      str_free(lst_get_ptr(noopt, i));
    }
    lst_free(noopt);
  }
  
  if (mod->estimate_ratemat) {
    for (i=0; i<numpar; i++)
      if (flag[i] == 0)
	mod->param_map[mod->ratematrix_idx+i] = opt_idx++;
  }
  if (numpar > 0) sfree(flag);

  if (mod->alt_subst_mods != NULL) {
    tempmod = mod->subst_mod;

    for (j=0; j<lst_size(mod->alt_subst_mods); j++) {
      noopt_backgd = noopt_selection = noopt_bgc=0;
      altmod = lst_get_ptr(mod->alt_subst_mods, j);
      mod->subst_mod = altmod->subst_mod;
      numpar = tm_get_nratematparams(mod);

      // first parse the noopt args.  Anything set to noopt means keep at 
      //initial value; do not optimize or set to main model values.
      if (numpar > 0) {
	noopt_flag = smalloc(numpar*sizeof(int)); 
	for (i=0; i < numpar; i++) noopt_flag[i] = 0;
      }
      else noopt_flag = NULL;
      
      if (altmod->noopt_arg != NULL) {
	noopt = lst_new_ptr(3);
	str_split(altmod->noopt_arg, ",", noopt);
	
	pos = lst_find_compare(noopt, BACKGD_STR, void_str_equals_charstr);
	if (pos >= 0) {
	  str_free(lst_get_ptr(noopt, pos));
	  lst_delete_idx(noopt, pos);
	  noopt_backgd = 1;
	  altmod->separate_backgd = 1;
	}
	pos = lst_find_compare(noopt, SELECTION_STR, void_str_equals_charstr);
	if (pos >= 0) {
	  str_free(lst_get_ptr(noopt, pos));
	  lst_delete_idx(noopt, pos);
	  noopt_selection = 1;
	  if (altmod->selection_idx < 0)
	    die("Need initial value to hold selection constant in alt mod\n");
	}
	pos = lst_find_compare(noopt, BGC_STR, void_str_equals_charstr);
	if (pos >= 0) {
	  str_free(lst_get_ptr(noopt, pos));
	  lst_delete_idx(noopt, pos);
	  noopt_bgc = 1;
	  if (altmod->bgc_idx < 0)
	    die("Need initial value to hold bgc constant in alt mod\n");
	}
	for (i=0; i < lst_size(noopt); i++) {
	  if (0 == tm_flag_subst_param_pos(mod, noopt_flag, (String*)lst_get_ptr(noopt, i))) 
	    die("ERROR: don't understand alt-mod param name %s\n",
		((String*)lst_get_ptr(noopt, i))->chars);
	  str_free(lst_get_ptr(noopt, i));
	}
	lst_free(noopt);
      }

      //special case: bgc.  Can only be present in alt model and not main model,
      //so cannot be tied to the main model, 
      //so must be optimized, regardless whether appears in param_list
      if (altmod->bgc_idx >= 0 && noopt_bgc == 0) {
	if (altmod->share_bgc != NULL && altmod->share_bgc != altmod)
	  mod->param_map[altmod->bgc_idx] = mod->param_map[altmod->share_bgc->bgc_idx];
	else mod->param_map[altmod->bgc_idx] = opt_idx++;
      }

      //now check param_list to see which are tied to main model
      if (numpar > 0) 
	use_main = smalloc(numpar*sizeof(int));
      else use_main = NULL;
      
      if (altmod->separate_model == 1) {
	for (i=0; i < numpar; i++) 
	  use_main[i] = 0;
      } else {
	for (i=0; i < numpar; i++)
	  use_main[i] = !noopt_flag[i];
	for (i=0; i<lst_size(altmod->param_list); i++) {
	  String *currparam;
	  int parenpos=-1, k;
	  List *tmplst=lst_new_ptr(2);
	  currparam = lst_get_ptr(altmod->param_list, i);
	  str_split(currparam, "#", tmplst);
	  if (lst_size(tmplst) == 2) {
	    int val = atoi(((String*)lst_get_ptr(tmplst, 1))->chars);
	    if (val >=1 && val <= lst_size(mod->alt_subst_mods))
	      currparam = lst_get_ptr(tmplst, 0);
	  }
	  for (k=0; k<currparam->length; k++)
	    if (currparam->chars[k]=='[') {
	      parenpos = k;
	      currparam->chars[parenpos]='\0';
	      currparam->length=parenpos;
	      break;
	    }
	  if (str_equals_nocase_charstr(currparam, BACKGD_STR))
	    altmod->separate_backgd = 1;
	  else if (str_equals_nocase_charstr(currparam, SELECTION_STR)) {
	    if (altmod->selection_idx < 0)
	      die("ERROR parsing alt-mod: got selection_idx < 0\n");
	    if (altmod->share_sel != NULL && altmod->share_sel != altmod)
	      mod->param_map[altmod->selection_idx] = mod->param_map[altmod->share_sel->selection_idx];
	    else mod->param_map[altmod->selection_idx] = opt_idx++;
	  }
	  else if (str_equals_nocase_charstr(currparam, BGC_STR));
	  else  {
	    int *tempflag=NULL;
	    if (numpar > 0) tempflag = smalloc(numpar*sizeof(int));
	    for (k=0; k < numpar; k++) tempflag[k] = 0;
	    if (0==tm_flag_subst_param_pos(mod, tempflag, currparam)) {
	      die("altmod %s couldn't parse parameter name %s\n",
		  tm_get_subst_mod_string(altmod->subst_mod),
		  currparam->chars);
	    }
	    for (k=0; k < numpar; k++) if (tempflag[k]) use_main[k] = 0;
	    if (tempflag != NULL) sfree(tempflag);
	  }
	  if (parenpos >= 0) {
	    currparam->chars[parenpos] = '[';
	    currparam->length = (int)strlen(currparam->chars);
	  }
	  lst_free_strings(tmplst);
	  lst_free(tmplst);
	}
      }

      if (altmod->selection_idx >= 0 && noopt_selection==0 &&
	  mod->param_map[altmod->selection_idx] < 0)
	mod->param_map[altmod->selection_idx] = 
	  mod->param_map[mod->selection_idx];
      
      if (noopt_backgd);   //hold backgd constant
      else if (altmod->separate_backgd == 0) {
	for (i=0; i < size; i++)
	  mod->param_map[altmod->backgd_idx+i] = mod->param_map[mod->backgd_idx+i];
      } else {
	for (i=0; i < size; i++)
	  mod->param_map[altmod->backgd_idx+i] = opt_idx++;
      }
      
      for (i=0; i < numpar; i++) {
	if (noopt_flag[i]);
	else if (use_main[i])
	  mod->param_map[altmod->ratematrix_idx+i] = 
	    mod->param_map[mod->ratematrix_idx+i];
	else mod->param_map[altmod->ratematrix_idx+i] = opt_idx++;
      }
	
      if (noopt_flag != NULL) 
	sfree(noopt_flag);
      if (use_main != NULL)
	sfree(use_main);
    }
    mod->subst_mod = tempmod;
  }
  tm_init_rmp(mod);
  return next_idx;
}


/* Wrapper for computation of likelihood */
double tm_likelihood_wrapper(Vector *params, void *data) {
  TreeModel *mod = (TreeModel*)data;
  double val;
  tm_unpack_params(mod, params, -1);
  val = -1 * tl_compute_log_likelihood(mod, mod->msa, NULL, NULL, mod->category,
				       NULL);
/*  if (1) {
     int i;
     printf("val=%f", val);
     for (i=0; i < params->size; i++) printf("\t%e", vec_get(params, i));
     printf("\n");
  }*/
  return val;
}


/*double tm_multi_likelihood_wrapper(Vector *params, void *data) {
  List *modlist = (List*)data;
  double ll=0, **scores;
  int i, nmod = lst_size(modlist);
  TreeModel *mod;
  scores = smalloc(nmod * sizeof(double*));
  for (i=0; i < nmod; i++)  {
    mod = (TreeModel*)lst_get_ptr(modlist, i);
    scores[i] = smalloc(mod->msa->ss->ntuples * sizeof(double));
    tm_unpack_params(mod, params, -1);
    tl_compute_log_likelihood(mod, mod->msa, NULL, scores[i], 
			      mod->category, NULL);
  }
  for (i=0; i < mod->msa->ss->ntuples; i++) {
    for (j=0; j < nmod; j++) {
      val += 
  }
  return ll;
  }*/

double tm_multi_likelihood_wrapper(Vector *params, void *data) {
  List *modlist = (List*)data;
  double ll=0;
  int i;
  for (i=0; i < lst_size(modlist); i++)  
    ll += tm_likelihood_wrapper(params, lst_get_ptr(modlist, i));
  return ll;
}

  


/* Set specified TreeModel according to specified parameter vector
   (exact behavior depends on substitution model).  An index offset
   can be specified for cases in which vectors of parameters are
   nested within larger vectors of parameters (set to -1 if not
   needed) */
void tm_unpack_params(TreeModel *mod, Vector *params_in, int idx_offset) {
  TreeNode *n;
  int nodeidx, i, j;
  List *traversal;
  Vector *params = mod->all_params;
  AltSubstMod *altmod;
  subst_mod_type temp_mod;
  MarkovMatrix *temp_mm;
  Vector *temp_backgd;
  double  sum;
  static Matrix *oldMatrix=NULL;

  if (oldMatrix != NULL && oldMatrix->nrows != mod->rate_matrix->size) {
    mat_free(oldMatrix);
    oldMatrix = NULL;
  }
  if (oldMatrix == NULL) {
    oldMatrix = mat_new(mod->rate_matrix->size, mod->rate_matrix->size);
    set_static_var((void**)&oldMatrix);
  }

  if (idx_offset == -1) idx_offset = 0;

  for (j=0; j<params->size; j++) {
    if (mod->param_map[j] >= 0)
      vec_set(params, j, vec_get(params_in, mod->param_map[j] + idx_offset));
  }

  mod->scale = vec_get(params, mod->scale_idx);
  mod->scale_sub = vec_get(params, mod->scale_idx+1);
  if (mod->selection_idx >= 0)
    mod->selection = vec_get(params, mod->selection_idx);
  else mod->selection = 0.0;
  i=0;
  if (mod->estimate_branchlens == TM_BRANCHLENS_CLOCK) {
    /* molecular clock; set total height of each node from parameter
       vector; temporarily store in dparent */
    for (nodeidx = 0; nodeidx < mod->tree->nnodes; nodeidx++) {
      n = lst_get_ptr(mod->tree->nodes, nodeidx);
      if (n->lchild == NULL) /* leaf */
	n->dparent = 0;
      else 
	n->dparent = vec_get(params, mod->bl_idx + i++);
    }
    /* set branch lengths */
    traversal = tr_postorder(mod->tree);
    /* first ensure ordering constraints are obeyed; can be violated
       during parameter estimation */
    for (nodeidx = 0; nodeidx < lst_size(traversal); nodeidx++) {
      n = lst_get_ptr(traversal, nodeidx);
      if (n->parent != NULL && n->dparent > n->parent->dparent)
	n->parent->dparent = n->dparent;
    }
    /* now set branch lengths to differences in heights */
    for (nodeidx = 0;  nodeidx < lst_size(traversal); nodeidx++) {
      n = lst_get_ptr(traversal, nodeidx);
      if (n->parent == NULL)
	n->dparent = 0;
      else
	n->dparent = n->parent->dparent - n->dparent;
    }
  } else {
    traversal = tr_preorder(mod->tree);
    for (nodeidx=0; nodeidx < lst_size(traversal); nodeidx++) {
      n = lst_get_ptr(traversal, nodeidx);
      if (n->parent == NULL) continue;

      /*Keeping the old convention here, even though it is a bit
	more complicated, for consistency's sake.  Set the bl of branches
	coming from root to half the value in parameter vector if model
	is reversible*/
      if ((n == mod->tree->lchild || n == mod->tree->rchild) &&
	  tm_is_reversible(mod))
	n->dparent = vec_get(params, mod->bl_idx + i)/2.0;
      else
	n->dparent = vec_get(params, mod->bl_idx + i);
      i++;
    }
  }

  /* backgd freqs */
  sum = 0;
  for (j = 0; j < mod->backgd_freqs->size; j++) 
    sum += vec_get(params, mod->backgd_idx+j);
  for (j = 0; j < mod->backgd_freqs->size; j++)
    vec_set(mod->backgd_freqs, j, vec_get(params, mod->backgd_idx+j)/sum);

  /* rate variation */
  if (mod->nratecats > 1) {
    if (mod->site_model)  {   /* Nielsen-yang site model parameterization */
      double denom = vec_get(params, mod->ratevar_idx)+
	vec_get(params, mod->ratevar_idx+1)+1.0;
      if (mod->nratecats != 4 && mod->nratecats != 8)
      die("ERROR: site_model with nratecats = %i not yet implemented", 
	  mod->nratecats);
      mod->freqK[0] = vec_get(params, mod->ratevar_idx)/denom;
      mod->freqK[1] = vec_get(params, mod->ratevar_idx+1)/denom;
      mod->freqK[2] = (1.0-mod->freqK[0]-mod->freqK[1])*mod->freqK[0]/(mod->freqK[0] + mod->freqK[1]);
      mod->freqK[3] = (1.0-mod->freqK[0]-mod->freqK[1])*mod->freqK[1]/(mod->freqK[0] + mod->freqK[1]);
      if (mod->nratecats == 8) {   //4 site models * 2 for each bgc state
	double bgcFrac = vec_get(params, mod->ratevar_idx+2)/(vec_get(params, mod->ratevar_idx+2)+1.0);
	for (i=0; i < 4; i++) {
	  mod->freqK[4+i] = bgcFrac * mod->freqK[i];
	  mod->freqK[i] *= (1.0-bgcFrac);
	}
      }
    } else {
      if (mod->empirical_rates) {
	for (j = 0; j < mod->nratecats; j++)
	  mod->freqK[j] = vec_get(params, mod->ratevar_idx+j);
	/* assume normalized */
      }
      else {                      /* discrete gamma model */
	mod->alpha = vec_get(params, mod->ratevar_idx);
	DiscreteGamma(mod->freqK, mod->rK, mod->alpha, mod->alpha, 
		      mod->nratecats, 0); 
      }
    }
  }

  /* lineage-specific models */ 
  if (mod->alt_subst_mods != NULL) {
    temp_mod = mod->subst_mod;
    temp_mm = mod->rate_matrix;
    temp_backgd = mod->backgd_freqs;

    for (j = 0; j < lst_size(mod->alt_subst_mods); j++) {
      altmod = lst_get_ptr(mod->alt_subst_mods, j);
      mod->subst_mod = altmod->subst_mod;

      if (altmod->backgd_freqs != NULL) {
	sum = 0;
	for (i = 0; i < altmod->backgd_freqs->size; i++) 
	  sum += vec_get(params, altmod->backgd_idx+i);
	for (i = 0; i < altmod->backgd_freqs->size; i++)
	  vec_set(altmod->backgd_freqs, i, 
		  vec_get(params, altmod->backgd_idx+i)/sum);
	mod->backgd_freqs = altmod->backgd_freqs;
      }

      if (altmod->selection_idx >= 0)
	altmod->selection = vec_get(params, altmod->selection_idx);
      else altmod->selection = 0.0;

      if (altmod->bgc_idx >= 0)
	altmod->bgc = vec_get(params, altmod->bgc_idx);
      else altmod->bgc = 0.0;

      mod->rate_matrix = altmod->rate_matrix;
      mat_copy(oldMatrix, mod->rate_matrix->matrix);
      tm_set_rate_matrix_sel_bgc(mod, params, altmod->ratematrix_idx,
				 altmod->selection + mod->selection, 
				 altmod->bgc);
      if ((altmod->subst_mod != JC69 && altmod->subst_mod != F81) || 
	  (altmod->selection + mod->selection != 0.0 || altmod->bgc != 0.0)) {
	if (!mat_equal(oldMatrix, altmod->rate_matrix->matrix)) 
	  mm_diagonalize(altmod->rate_matrix);
      }
      mod->subst_mod = temp_mod;
      mod->rate_matrix = temp_mm;
      mod->backgd_freqs = temp_backgd;
    }
  }

  /* redefine substitution matrix */
  mat_copy(oldMatrix, mod->rate_matrix->matrix);
  tm_set_rate_matrix_sel_bgc(mod, params, mod->ratematrix_idx,
			     mod->selection, 0.0);

  /* diagonalize, if necessary */
  if ((mod->subst_mod != JC69 && mod->subst_mod != F81) || 
      mod->selection != 0.0) {
    if (!mat_equal(oldMatrix, mod->rate_matrix->matrix)) 
      mm_diagonalize(mod->rate_matrix);
  }

  /* set exponentiated version at each edge */
  tm_set_subst_matrices(mod); 
}


/* Scale the rate matrix of the specified tree model such that the
   expected rate of substitution at equilibrium is 1.  This is the
   standard convention; it allows the unit of measurement of branch
   lengths to be expected substitutions/site.  
   NOTE: now returns scaling factor, which can be used to adjust
   branch lengths if the rate matrix has not been scaled throughout the
   fitting procedure.
*/ 
double tm_scale_rate_matrix(TreeModel *mod) {
  double scale = 0;
  int i, j;
  for (i = 0; i < mod->rate_matrix->size; i++) {
    double rowsum = 0;
    for (j = 0; j < mod->rate_matrix->size; j++) {
      if (j != i) rowsum += mm_get(mod->rate_matrix, i, j);
    }
    scale += (vec_get(mod->backgd_freqs, i) * rowsum);
  }

  mm_scale(mod->rate_matrix, (mod->order + 1)/scale);
  return scale/(mod->order + 1);
}


/* scale a parameter vector according to a specified rate matrix scale
   factor.  Branch length params are multiplied by the specified factor
   and rate matrix params by its inverse .
   NOTE: it really doesn't make sense to scale all rate matrix params by
   1/scale_factor (for example, a parameter like transition/transversion 
   ratio shouldn't be scaled).  Would make more sense to have model-specific
   function that does this, or which dictates which params are scaled.  But
   that requires yet another model-specific function.  This is only really
   used in phyloBoot anyway.
*/
void tm_scale_params(TreeModel *mod, Vector *params, double scale_factor) {
  int i;
  int nbl = tm_get_nbranchlenparams(mod);
  int nrm = tm_get_nratematparams(mod);

  for (i = 0; i < nbl; i++)
    vec_set(params, mod->bl_idx+i, 
	    vec_get(params, mod->bl_idx + i) * scale_factor);
  for (i=0; i<nrm; i++)
    vec_set(params, mod->ratematrix_idx + i, 
	    vec_get(params, mod->ratematrix_idx + i) / scale_factor);
}


/* This is just called after some functions which initialize parameters.
   if rootleaf is defined, it makes sure that the corresponding value in 
   the parameter vector is set to zero */
void tm_init_rootleaf(TreeModel *mod, Vector *params) {
  List *traversal = tr_preorder(mod->tree);
  int idx=0, i;
  TreeNode *n;
  if (mod->root_leaf_id < 0) return;
  for (i=0; i<lst_size(traversal); i++) {
    n = lst_get_ptr(traversal, i);
    if (n == mod->tree) continue;
    if (n->id == mod->root_leaf_id) {
      vec_set(params, mod->bl_idx + idx, 0.0);
      break;
    }
    idx++;
  }
  if (i >= lst_size(traversal))
    die("ERROR tm_init_rootleaf: i (%i) >= lst_size(traversal) (%i)\n",
	i, lst_size(traversal));
  return;
}
  
void tm_init_const_branches(TreeModel *mod, Vector *params) {
  int node_idx, temp_idx=0;
  List *traversal = tr_preorder(mod->tree);
  TreeNode *n;

  for (node_idx=0; node_idx < lst_size(traversal); node_idx++) {
    n = lst_get_ptr(traversal, node_idx);
    if (n->parent == NULL) continue;  //skip root
    if (n->hold_constant)
      vec_set(params, mod->bl_idx + temp_idx, n->dparent);
    temp_idx++;
  }
}


/* initializes all branch lengths to designated constant; initializes
   rate-matrix params using specified kappa; kappa ignored for JC69;
   REV and UNREST initialized as if HKY.  Initializes alpha as
   specified, if dgamma.  In the case of empirical rates, uniform
   weights are used for initialization. */
Vector *tm_params_init(TreeModel *mod, double branchlen, double kappa,
                       double alpha) {
  int nparams = tm_get_nparams(mod);
  Vector *params = vec_new(nparams);
  int i, nbranches, size;

  tm_setup_params(mod, 0);

  /* initialize branch-length parameters */
  nbranches = tm_get_nbranchlenparams(mod);
  vec_set(params, mod->scale_idx, 1.0);
  vec_set(params, mod->scale_idx+1, 1.0);

  if (mod->estimate_branchlens == TM_BRANCHLENS_CLOCK)  {     
                                /* set parameter to constant times
                                   height of corresponding node
                                   (parameters represent total branch
                                   length to ancestral nodes)  */
    int idx=0;
    for (i = 0; i < mod->tree->nnodes; i++) {
      TreeNode *n = lst_get_ptr(mod->tree->nodes, i);
      if (n->lchild != NULL) {  /* non-leaf */
        vec_set(params, mod->bl_idx+idx, branchlen * n->height);
	idx++;
      }
    }
  }
  else {                        /* simply set branch length to constant */
    for (i = 0; i < nbranches; i++) 
      vec_set(params, mod->bl_idx+i, branchlen);
    tm_init_rootleaf(mod, params);
    tm_init_const_branches(mod, params);
  }

  if (mod->backgd_freqs == NULL) {
    size = mod->rate_matrix->size;
    for (i = 0; i < size; i++)
      vec_set(params, mod->backgd_idx+i, 1.0/(double)size);
  }
  else {
    size = mod->backgd_freqs->size;
    for (i = 0; i < size; i++)
      vec_set(params, mod->backgd_idx+i, vec_get(mod->backgd_freqs, i));
  }

  if (mod->nratecats > 1) {
    if (mod->site_model)
      tm_site_model_set_ml_weights(mod, params, mod->freqK);
    else {
      if (mod->empirical_rates)
	for (i = 0; i < mod->nratecats; i++) 
	  vec_set(params, mod->ratevar_idx+i, mod->freqK[i]);
      else
	vec_set(params, mod->ratevar_idx, alpha);
    }
  }

  /* initialize rate-matrix parameters */
  tm_rate_params_init(mod, params, mod->ratematrix_idx, kappa);

  if (mod->selection_idx >= 0)
    vec_set(params, mod->selection_idx, mod->selection);

  if (mod->alt_subst_mods != NULL) {
    AltSubstMod *altmod;
    subst_mod_type tempmod = mod->subst_mod;
    int j;
    for (i = 0; i<lst_size(mod->alt_subst_mods); i++) {
      altmod = lst_get_ptr(mod->alt_subst_mods, i);
      mod->subst_mod = altmod->subst_mod;
      tm_rate_params_init(mod, params, altmod->ratematrix_idx, kappa);
      
      if (altmod->backgd_freqs == NULL) {
	for (j=0; j < size; j++)
	  vec_set(params, altmod->backgd_idx+j, vec_get(params, mod->backgd_idx+j));
      } else {
	for (j=0; j < size; j++)
	  vec_set(params, altmod->backgd_idx+j, vec_get(altmod->backgd_freqs, j));
      }
      if (altmod->selection_idx >= 0)
	vec_set(params, altmod->selection_idx, altmod->selection);
      if (altmod->bgc_idx >= 0)
	vec_set(params, altmod->bgc_idx, altmod->bgc);
    }
    mod->subst_mod = tempmod;
  }
  return params;
}


/* initializes branch lengths and rate matrix parameters
   randomly; can be used multiple times to ensure the MLE is real */
Vector *tm_params_init_random(TreeModel *mod) {
  int i, size=mod->rate_matrix->size;
  Vector *params = vec_new(tm_get_nparams(mod));
  int nbranches = tm_get_nbranchlenparams(mod);
  int nratematparams = tm_get_nratematparams(mod);
  TreeNode *n;
  List *traversal;
  double *heights;

  tm_setup_params(mod, 0);
  
  if (mod->estimate_branchlens == TM_SCALE_ONLY) {
    vec_set(params, mod->scale_idx, 0.001+2.0*unif_rand());
    vec_set(params, mod->scale_idx+1, 0.001+2.0*unif_rand());
  } else {
    vec_set(params, mod->scale_idx, 1.0);
    vec_set(params, mod->scale_idx+1, 1.0);
  }
  
  if  (mod->estimate_branchlens == TM_BRANCHLENS_CLOCK) { 
    int idx=0;
    /* in this case, have to ensure ancestral nodes have larger values
       than their descendants */
    traversal = tr_postorder(mod->tree);
    heights = smalloc(mod->tree->nnodes * sizeof(double));
    for (i = 0; i < lst_size(traversal); i++) {
      n = lst_get_ptr(traversal, i);
      if (n->lchild == NULL)    /* leaf */
        heights[n->id] = 0;
      else
        heights[n->id] = 
          max(heights[n->lchild->id], heights[n->rchild->id]) +
          0.01 + (0.5 - 0.01)*unif_rand();
    }
    for (i = 0; i < mod->tree->nnodes; i++) { /* has to follow index
                                                 order, excluding leaves */
      n = lst_get_ptr(mod->tree->nodes, i);
      if (n->lchild != NULL) {
        vec_set(params, mod->bl_idx+idx, heights[n->id]);      
	idx++;
      }
    }
    sfree(heights);
  }
  else {                        /* no clock */
    for (i = 0; i < nbranches; i++)
      vec_set(params, mod->bl_idx+i, 
              0.01 + (0.5 - 0.01) * unif_rand());
              /* we'll use the interval from 0.01 to 0.5 */
    tm_init_rootleaf(mod, params);
    tm_init_const_branches(mod, params);
  }

  if (mod->nratecats > 1) {
    if (mod->site_model) {
      int npar = tm_get_nratevarparams(mod);
      for (i=0; i < npar; i++)
	vec_set(params, mod->ratevar_idx + i, unif_rand()*5.0);
    } 
    else {
      if (mod->empirical_rates) { /* empirical rate model (category weights) */
	double val, sum = 0;
	for (i = 0; i < mod->nratecats; i++) {
	  vec_set(params, mod->ratevar_idx + i, 
		  val = 0.1 + (1 - 0.5) * unif_rand());
	  /* we'll use the interval from 0.1 to 1 */
	  sum += val;
	}
	for (i = 0; i < mod->nratecats; i++) /* normalize */
	  vec_set(params, mod->ratevar_idx+i, 
		  vec_get(params, mod->ratevar_idx + i) / sum);
      }
      
      else                        /* discrete gamma (alpha) */
	vec_set(params, mod->ratevar_idx, 
		0.5 + (10 - 0.5) * unif_rand());
      /* we'll use the interval from 0.5 to 10 */
    }
  }

  for (i = 0; i < nratematparams; i++) 
    vec_set(params, mod->ratematrix_idx+i, 
	    0.1 + (5 - 0.1) * unif_rand());
                                /* we'll use the interval from 0.1 to 5 */
  if (mod->estimate_backgd) {
    double sum=0.0;
    for (i=0; i<size; i++) {
      vec_set(params, mod->backgd_idx+i, unif_rand());
      sum += vec_get(params, mod->backgd_idx+i);
    }
    for (i=0; i<size; i++)
      vec_set(params, mod->backgd_idx+i, 
	      vec_get(params, mod->backgd_idx+i)/sum);
  }

  if (mod->selection_idx >= 0 && mod->param_map[mod->selection_idx] >= 0)
    vec_set(params, mod->selection_idx, unif_rand()*2-1.0);

  if (mod->alt_subst_mods != NULL) {
    AltSubstMod *altmod;
    subst_mod_type temp_mod = mod->subst_mod;
    int j;
    for (j=0; j<lst_size(mod->alt_subst_mods); j++) {
      altmod = lst_get_ptr(mod->alt_subst_mods, j);
      mod->subst_mod = altmod->subst_mod;
      if (altmod->rate_matrix != NULL) {
	nratematparams = tm_get_nratematparams(mod);
	for (i=0; i<nratematparams; i++)
	  vec_set(params, altmod->ratematrix_idx+i, 0.1 + 
		  (5-0.1)*unif_rand());
      }
      if (altmod->separate_backgd) {
	double sum=0.0;
	for (i=0; i<size; i++)  {
	  vec_set(params, altmod->backgd_idx+i, unif_rand());
	  sum += vec_get(params, altmod->backgd_idx+i);
	}
	for (i=0; i<size; i++)
	  vec_set(params, altmod->backgd_idx+i, 
		  vec_get(params, altmod->backgd_idx+i)/sum);
      } else {
	for (i=0; i < size; i++) 
	  vec_set(params, altmod->backgd_idx+i, vec_get(params, mod->backgd_idx+i));
      }
      if (mod->param_map[altmod->selection_idx] >= 0)
	vec_set(params, altmod->selection_idx, unif_rand()*2-1.0);
      if (mod->param_map[altmod->bgc_idx] >= 0)
	vec_set(params, altmod->bgc_idx, unif_rand()*2.0-1.0);
    }
    mod->subst_mod = temp_mod;
  }

  return params;
}


//recursive Fitch parsimony algorithm.
//Assumes that numMin and minState have already been set for leaf nodes
//recurse downward and set state to intersection if exists, 
//otherwise union
int tm_fitch_rec_down(TreeNode *tree, int *numMin, int **minState) {
  int sum;
  int i, j, child[2];

  if (tree->lchild==NULL) return 0;
  sum = tm_fitch_rec_down(tree->lchild, numMin, minState);
  sum += tm_fitch_rec_down(tree->rchild, numMin, minState);

  child[0] = tree->lchild->id;
  child[1] = tree->rchild->id;

  numMin[tree->id]=0;
  
  //first see if there's an intersection in minStates for children
  for (i=0; i<numMin[child[0]]; i++)
    for (j=0; j<numMin[child[1]]; j++)
      if (minState[child[0]][i] == minState[child[1]][j]) 
	minState[tree->id][numMin[tree->id]++] = minState[child[0]][i];
  if (numMin[tree->id] > 0) return sum;
  

  //otherwise take union and add 1 to cost
  for (i=0; i<2; i++) 
    for (j=0; j<numMin[child[i]]; j++)
      minState[tree->id][numMin[tree->id]++] = minState[child[i]][j];
  return sum+1;
}


//recursive Fitch parsimony algorithm part 2.
//After tm_fitch_rec_down has been called, recurses back up from
//root to leaves and assigns parsimonious state(s)
void tm_fitch_rec_up(int *nodecost, TreeNode *tree, 
		     int *numMin, int **minState, int pState) {
  int node, state=-1, i;

  node = tree->id;
  nodecost[node]=0;
  
  //get state at node.  If only one minimum, we already have it.
  //Otherwise, if one of the minimums matches parent state, use that.
  //Otherwise pick one at random.
  if (tree->parent != NULL) {
    if (numMin[node]==1) state = minState[node][0];
    else {
      for (i=0; i<numMin[node]; i++)
	if (minState[node][i] == pState) {
	  state = pState;
	  break;
	}
      if (i == numMin[node]) 
	state = minState[node][(int)(unif_rand()*(double)numMin[node])];
    }      

    //now add cost to nodecost if state != parentState
    if (state != pState) nodecost[node]=1;
  } else state = pState;
  
  if (tree->lchild != NULL) {
    tm_fitch_rec_up(nodecost, tree->lchild, numMin, minState, state);
    tm_fitch_rec_up(nodecost, tree->rchild, numMin, minState, state);
  }
}



//initialize branchlengths to average number of mutations under parsimony,
//and then applies Jukes Cantor correction.
//returns parsimony score.
//If params is NULL, sets the branchlengths in mod->tree directly.
//Otherwise sets the parameter vector
double tm_params_init_branchlens_parsimony(Vector *params, TreeModel *mod, 
					   MSA *msa, int cat) {
  int i, numnode = mod->tree->nnodes;
  int numstate=(int)strlen(msa->alphabet), **minState, *numMinState;
  int tupleIdx, spec, node, rootMinState, *nodecost, params_idx;
  double *brlen, weight, denom=0, totalCost=0;
  List *traversal;
  char currCh;
  TreeNode *currNode;

  if (msa->ss==NULL) 
    die("ERROR: tm_params_init_branchlens_parsimony needs msa->ss!=NULL\n");

  if (mod->order!=0) 
    die("ERROR: tm_params_init_branches currently only works for order 0 models\n");

  if  (mod->estimate_branchlens == TM_BRANCHLENS_CLOCK) { 
    die("Sorry, parsimony algorithm not implemented for molecular clock\n");
  }


  //this array keeps track of number of mutations on each branch
  brlen = smalloc(numnode*sizeof(double));
  for (i=0; i<numnode; i++)
    brlen[i] = 0;

  //get sequence index if not already there
  if (mod->msa_seq_idx==NULL)
    tm_build_seq_idx(mod, msa);

  minState = smalloc(numnode*sizeof(int*));
  for (i=0; i<numnode; i++)
    minState[i] = smalloc(numstate*sizeof(int));
  numMinState = smalloc(numnode*sizeof(int));
  nodecost = smalloc(numnode*sizeof(int));
  traversal = tr_preorder(mod->tree);

  for (tupleIdx=0; tupleIdx<msa->ss->ntuples; tupleIdx++) {
    checkInterruptN(tupleIdx, 1000);
    weight = (cat >=0 ? msa->ss->cat_counts[cat][tupleIdx] : 
	      msa->ss->counts[tupleIdx]);
    if (weight == 0.0) continue;

    //get states at tips
    for (node=0; node<numnode; node++) {
      spec = mod->msa_seq_idx[node];
      if (spec==-1) continue;
      currCh = ss_get_char_tuple(msa, tupleIdx, spec, 0);
      if (msa->is_missing[(int)currCh] || currCh==GAP_CHAR) {
	numMinState[node] = numstate;
	for (i=0; i<numstate; i++) {
	  minState[node][i] = i;
	}
      } else {
	numMinState[node]=1;
	for (i=0; i<numstate; i++) 
	  if (msa->alphabet[i] == currCh) {
	    minState[node][0] = i;
	    break;
	  }
	if (i >= numstate)
	  die("ERROR tm_params_init_branchlens_parsimony: i (%i) >= numstate (%i)\n", i, numstate);
      }
    }
    totalCost += weight*(double)tm_fitch_rec_down(mod->tree, numMinState, minState);
    if (numMinState[mod->tree->id] > 0) 
      rootMinState = minState[mod->tree->id][(int)(unif_rand()*(double)numMinState[mod->tree->id])];
    else rootMinState = minState[mod->tree->id][0];

    tm_fitch_rec_up(nodecost, mod->tree, numMinState, minState, rootMinState);

    denom += weight;
    for (node=0; node<numnode; node++)
      brlen[node] += nodecost[node]*weight;
  }

  //this is without JC correction
 // for (node=0; node<numnode; node++)
  //  brlen[node] /= denom;

 //try JC correction:
  for (node=0; node<numnode; node++) {
    if (brlen[node]!=0.0) {
      brlen[node] = -0.75*log(1.0-4.0*brlen[node]/(3.0*denom));
    }
  }
  if (params == NULL) {
    for (node=0; node < numnode; node++)
      ((TreeNode*)(lst_get_ptr(mod->tree->nodes, node)))->dparent = brlen[node];
  }   
  else if (mod->estimate_branchlens == TM_BRANCHLENS_ALL) {
    params_idx = 0;
    for (node=0; node<lst_size(traversal); node++) {
      currNode = (TreeNode*)lst_get_ptr(traversal, node);
      if (currNode->parent == NULL) continue;
      if (currNode == mod->tree->lchild && tm_is_reversible(mod)) 
	vec_set(params, params_idx++, 
		brlen[currNode->id] + brlen[mod->tree->rchild->id]);
      else if (currNode != mod->tree->rchild || 
	       !tm_is_reversible(mod))
	vec_set(params, params_idx++, brlen[currNode->id]);
    }
  } else if (mod->estimate_branchlens==TM_SCALE_ONLY) {
    double sum=0.0;
    for (node=0; node<numnode; node++)
      sum += brlen[node];
    vec_set(params, 0, sum);
    if (mod->subtree_root != NULL) {
      sum=0.0;
      traversal = tr_preorder(mod->subtree_root);
      for (node=0; node<lst_size(traversal); node++) {
	currNode = (TreeNode*)lst_get_ptr(traversal,node);
	sum += brlen[currNode->id];
      }
      vec_set(params, 1, sum/vec_get(params, 0));
    }
    else if (mod->in_subtree != NULL) {
      sum = 0.0;
      for (i=0; i < mod->tree->nnodes; i++)
	if (mod->in_subtree[i]) {
	  currNode = lst_get_ptr(mod->tree->nodes, i);
	  sum += brlen[currNode->id];
	}
      vec_set(params, 1, sum/vec_get(params, 0));
    }
  }

	
  sfree(brlen);
  for (i=0; i<numnode; i++)
    sfree(minState[i]);
  sfree(minState);
  sfree(numMinState);
  sfree(nodecost);
  //  printf("totalCost=%f\n", totalCost);
  tm_init_const_branches(mod, params);
  return totalCost;
}


/* Functions to initialize a parameter vector from an existing tree model */
Vector *tm_params_new_init_from_model(TreeModel *mod) {
  Vector *params = vec_new(tm_get_nparams(mod));
  tm_params_init_from_model(mod, params, TRUE);
  return params;
}

void tm_params_init_from_model(TreeModel *mod, Vector *params, int setup_params) {
  int nodeidx, j, i;
  List *traversal;
  TreeNode *n;

  if (setup_params)
    tm_setup_params(mod, 0);
  //  tr_print(stdout, mod->tree, 1);
  vec_set(params, mod->scale_idx, mod->scale);
  vec_set(params, mod->scale_idx+1, mod->scale_sub);
  i=0;
  if (mod->estimate_branchlens == TM_BRANCHLENS_CLOCK) {
   /* compute height of each node */
    double *heights = smalloc(mod->tree->nnodes * sizeof(double));
    traversal = tr_postorder(mod->tree);
    for (nodeidx = 0; nodeidx < lst_size(traversal); nodeidx++) {
      n = lst_get_ptr(traversal, nodeidx);
      if (n->lchild == NULL)    /* leaf */
        heights[n->id] = 0;
      else 
	heights[n->id] = max(n->lchild->dparent + heights[n->lchild->id],
			     n->rchild->dparent + heights[n->rchild->id]);
    }
    /* set params equal to heights, in order of ids (skipping leaves) */
    for (nodeidx = 0; nodeidx < mod->tree->nnodes; nodeidx++) {
      n = lst_get_ptr(mod->tree->nodes, nodeidx);
      if (n->lchild != NULL)
        vec_set(params, mod->bl_idx + i++, heights[n->id]);
    }
    sfree(heights);
  } 
  else {
    traversal = tr_preorder(mod->tree);
    for (nodeidx = 0; nodeidx < lst_size(traversal); nodeidx++) {
      n = lst_get_ptr(traversal, nodeidx);
      if (n->parent == NULL) continue;

      /* Note, previously in reversible models, the value of 
	 init_mod->tree->lchild->dparent was ignored and the length of root 
	 branch was set to 2*init_mod->tree->rchild->dparent.  Now using 
	 the sum of the left and right, which may cause slightly different 
	 results than previous versions.
       */ 
      if ((n == mod->tree->lchild || n == mod->tree->rchild) &&
	  tm_is_reversible(mod)) {
	if (mod->estimate_branchlens == TM_BRANCHLENS_ALL)
	  vec_set(params, mod->bl_idx + i, (mod->tree->lchild->dparent +
					    mod->tree->rchild->dparent));
	else {
	  /* do this case separately so that if we are only scaling
	     the tree, we get back a set of branchlens that correlate 
	     nicely with the ones in the initial tree*/
	  vec_set(params, mod->bl_idx + i, 2.0*n->dparent);
	}
      }
      else vec_set(params, mod->bl_idx+i, n->dparent);
      i++;
    }
    tm_init_rootleaf(mod, params);
  }

  if (mod->backgd_freqs != NULL) {
    for (i=0; i<mod->backgd_freqs->size; i++)
      vec_set(params, mod->backgd_idx+i, vec_get(mod->backgd_freqs, i));
  }

  /* next parameters are for rate variation */
  if (mod->nratecats > 1 || mod->alpha < 0) {
    if (mod->site_model) 
      tm_site_model_set_ml_weights(mod, params, mod->freqK);
    else if (mod->empirical_rates) {
      for (j = 0; j < mod->nratecats; j++)
	vec_set(params, mod->ratevar_idx+j, mod->freqK[j]);
    } else                        /* discrete gamma model */
      vec_set(params, mod->ratevar_idx, mod->alpha);
  }

  /* initialize rate-matrix parameters */
  //  if (mod->estimate_ratemat)
  tm_rate_params_init_from_model(mod, params, mod->ratematrix_idx,
				 mod->selection, 0.0);
  
  if (mod->selection_idx >= 0)
    vec_set(params, mod->selection_idx, mod->selection);

  /* Now initialize alt_models */
  if (mod->alt_subst_mods != NULL) {
    subst_mod_type tempmod = mod->subst_mod;
    AltSubstMod *altmod;
    MarkovMatrix *tempmm = mod->rate_matrix;
    Vector *tempfreq = mod->backgd_freqs;
    for (j=0; j<lst_size(mod->alt_subst_mods); j++) {
      altmod = lst_get_ptr(mod->alt_subst_mods, j);
      mod->subst_mod = altmod->subst_mod;
      if (altmod->rate_matrix == NULL)
	altmod->rate_matrix = mm_create_copy(mod->rate_matrix);
      mod->rate_matrix = altmod->rate_matrix;
      if (altmod->backgd_freqs != NULL) 
	mod->backgd_freqs = altmod->backgd_freqs;
      if (altmod->selection_idx >= 0)
	vec_set(params, altmod->selection_idx, altmod->selection);
      if (altmod->bgc_idx >= 0)
	vec_set(params, altmod->bgc_idx, altmod->bgc);
      tm_rate_params_init_from_model(mod, params, altmod->ratematrix_idx,
				     altmod->selection + mod->selection, altmod->bgc);
      for (i=0; i < mod->backgd_freqs->size; i++)
	vec_set(params, altmod->backgd_idx+i, vec_get(mod->backgd_freqs, i));
      mod->subst_mod = tempmod;
      mod->rate_matrix = tempmm;
      mod->backgd_freqs = tempfreq;
    }
  }

}

/* Given a codon model, create and return the induced amino acid model */
TreeModel *tm_induced_aa(TreeModel *codon_mod) {
  TreeModel *retval;
  char *codon_to_aa = get_codon_mapping(codon_mod->rate_matrix->states);
  Vector *aa_freqs = vec_new(strlen(AA_ALPHABET));
  MarkovMatrix *aa_mat = mm_new(strlen(AA_ALPHABET), AA_ALPHABET, CONTINUOUS);
  int i, j;
  int nstates = codon_mod->rate_matrix->size;

  if (codon_mod->order != 2)
    die("ERROR: tm_induced_aa: codon_mod->order=%i (should be 2)\n", codon_mod->order);
  vec_zero(aa_freqs);

  /* compute induced equilibrium freqs */
  for (i = 0; i < nstates; i++) {
    int aa_state_i = aa_mat->inv_states[(int)codon_to_aa[i]]; 
                                /* state number corresponding to amino
                                   acid which corresponds to codon i */
    vec_set(aa_freqs, aa_state_i, vec_get(aa_freqs, aa_state_i) + 
                   vec_get(codon_mod->backgd_freqs, i));
  }

  /* compute induced matrix */
  for (i = 0; i < nstates; i++) {
    int aa_state_i = aa_mat->inv_states[(int)codon_to_aa[i]]; 
    double cond_freq = safediv(vec_get(codon_mod->backgd_freqs, i),
                               vec_get(aa_freqs, aa_state_i)); 
                                /* freq of codon i given its aa */
    for (j = 0; j < nstates; j++) {
      int aa_state_j = aa_mat->inv_states[(int)codon_to_aa[j]]; 
      mm_set(aa_mat, aa_state_i, aa_state_j, 
             mm_get(aa_mat, aa_state_i, aa_state_j) + 
             cond_freq * mm_get(codon_mod->rate_matrix, i, j));
    }
  }

  retval = tm_new(tr_create_copy(codon_mod->tree), aa_mat, aa_freqs, 
                  UNDEF_MOD, NULL, codon_mod->nratecats, codon_mod->alpha, 
                  NULL, codon_mod->root_leaf_id);

  retval->msa = codon_mod->msa;
  for (i = 0; i < codon_mod->nratecats; i++) {
    retval->freqK[i] = codon_mod->freqK[i];
    retval->rK[i] = codon_mod->rK[i];
  }
  retval->empirical_rates = codon_mod->empirical_rates;

  /* NOTE: ignoring params, tree_posteriors, etc. */

  sfree(codon_to_aa);
  return retval;
}

/* return number of parameters for specified TreeModel (based on
   number of taxa and substitution model) */
int tm_get_nparams(TreeModel *mod) {
  int rv, neqfreq, nummod=1;
  
  /*old code:
  return (tm_get_nbranchlenparams(mod) + tm_get_neqfreqparams(mod) + 
          tm_get_nratevarparams(mod) + tm_get_nratematparams(mod));    
   */
  
  //2 for scale and subtree scale
  rv = 2 + tm_get_nbranchlenparams(mod) + tm_get_nratevarparams(mod) + 
    tm_get_nratematparams(mod);
  neqfreq = tm_get_neqfreqparams(mod);
  if (mod->selection_idx >= 0) rv++;
  if (mod->alt_subst_mods != NULL) {
    subst_mod_type temp_mod = mod->subst_mod;
    AltSubstMod *altmod;
    int i;
    for (i=0; i<lst_size(mod->alt_subst_mods); i++) {
      altmod = lst_get_ptr(mod->alt_subst_mods, i);
      mod->subst_mod = altmod->subst_mod;
      rv += tm_get_nratematparams(mod);
      if (altmod->selection_idx >= 0) rv++;
      if (altmod->bgc_idx >= 0) rv++;
      nummod++;
    }
    mod->subst_mod = temp_mod;
  }
  rv += nummod*neqfreq;
  return rv;
}

int tm_get_neqfreqparams(TreeModel *mod) {
  if (mod->backgd_freqs == NULL) return mod->rate_matrix->size;
  return mod->backgd_freqs->size;
}

int tm_get_nratevarparams(TreeModel *mod) {
  if (mod->nratecats > 1 || mod->alpha < 0) {
    if (mod->site_model) {
      if (mod->nratecats == 4) return 2;   /* nielsen-yang parameterization 2 parameters-> 4 categories */
      if (mod->nratecats == 8) return 3;  /* nielsen-yang plus one param for bgc frequency */
    }
    else if (!mod->empirical_rates)  /* discrete gamma (alpha parameter) */
      return 1;
    else if (mod->nratecats > 1) /* empirical rates */
      return mod->nratecats;
    else if (mod->alpha < 0)    /* empirical rates but temp. disabled */
      return -(int)mod->alpha;       /* (here, nratecats is stored as -alpha) */
  }
  return 0;
}


int tm_get_nleaf(TreeModel *mod) {
  int i,retval=0;
  for (i=0; i<mod->tree->nnodes; i++) {
    TreeNode *n = lst_get_ptr(mod->tree->nodes, i);
    if (n->lchild==NULL) retval++;
  }
  return retval;
}

/** Return number of branch length params */
int tm_get_nbranchlenparams(TreeModel *mod) {
  if (mod->estimate_branchlens == TM_BRANCHLENS_CLOCK) {
    return ((mod->tree->nnodes + 1) / 2 - 1); /* number of ancestral nodes */
  }
  return mod->tree->nnodes - 1;
}


/** Build index of leaf ids to sequence indices in given alignment.
    Leaves not present in the alignment will be ignored.  Also, it's
    not required that there's a leaf for every sequence in the
    alignment. */
void tm_build_seq_idx(TreeModel *mod, MSA *msa) {
  int i, idx;  
  mod->msa_seq_idx = smalloc(mod->tree->nnodes * sizeof(int));
  for (i = 0; i < mod->tree->nnodes; i++) {
    TreeNode *n = lst_get_ptr(mod->tree->nodes, i);
    mod->msa_seq_idx[i] = -1;
    if (n->lchild == NULL && n->rchild == NULL &&
        (idx = msa_get_seq_idx(msa, n->name)) >= 0)
      mod->msa_seq_idx[i] = idx;
  }
}

/** Prune away leaves in tree that don't correspond to sequences in a
    given alignment.  Warning: root of tree (value of mod->tree) may
    change. */
void tm_prune(TreeModel *mod,   /* TreeModel whose tree is to be pruned  */
              MSA *msa,         /* Alignment; all leaves whose names
                                    are not in msa->names will be
                                    pruned away */
              List *names       /* Will contain names of deleted
                                   leaves on return.  Must be
                                   pre-allocated */
              ) {
  int i, j, old_nnodes = mod->tree->nnodes, *id_map = NULL;

  if (mod->tree->nnodes < 3)
    die("ERROR tm_prune: tree has %i nodes (should have at least 3)\n", 
	mod->tree->nnodes);

  lst_clear(names);
  for (i = 0; i < msa->nseqs; i++)
    lst_push_ptr(names, str_new_charstr(msa->names[i]));

  if (mod->alt_subst_mods_ptr != NULL)
    id_map = smalloc(mod->tree->nnodes*sizeof(int));

  tr_prune(&mod->tree, names, TRUE, id_map);

  if (mod->tree == NULL) {
    if (id_map != NULL) sfree(id_map);
    return;                     /* whole tree pruned away; special case */
  }

  if (lst_size(names) > 0) {
    /* free memory for eliminated nodes */
    for (i = mod->tree->nnodes; i < old_nnodes; i++) {
      for (j = 0; j < mod->nratecats; j++)
        if (mod->P[i][j] != NULL) mm_free(mod->P[i][j]);
      sfree(mod->P[i]);
    }
  }

  /* necessary because parameter indices can change */
  if (mod->rate_matrix_param_row != NULL) {
    tm_free_rmp(mod);
    tm_init_rmp(mod);
  }

  /* re-map alt_subst_mods_ptr if necessary */
  if (mod->alt_subst_mods_ptr != NULL) {
    AltSubstMod ***old = mod->alt_subst_mods_ptr;
    mod->alt_subst_mods_ptr = smalloc(mod->tree->nnodes * sizeof(AltSubstMod**));
    for (i=0; i < old_nnodes; i++) {
      if (id_map[i] == -1) {
	for (j=0; j < mod->nratecats; j++)
	  sfree(old[i][j]);
	sfree(old[i]);
      } else 
	mod->alt_subst_mods_ptr[id_map[i]] = old[i];
    }
    sfree(old);
    sfree(id_map);
  }
}

/** Extrapolate tree model and prune leaves not represented in
   alignment (see tr_scale_by_subtree).  Returns scale factor */
double tm_extrapolate_and_prune(TreeModel *mod, TreeNode *extrapolate_tree, 
                                MSA *msa, List *pruned_names) {
  int i;
  TreeNode *t = tr_create_copy(extrapolate_tree);
  double scale = tr_scale_by_subtree(t, mod->tree);
  for (i = 0; i < msa->nseqs; i++)
    lst_push_ptr(pruned_names, str_new_charstr(msa->names[i]));
  tr_prune(&t, pruned_names, TRUE, NULL);
  tm_reset_tree(mod, t);
  return scale;
}

/* Reset TreeModel with new or altered tree. */
void tm_reset_tree(TreeModel *mod,   /** TreeModel */
                   TreeNode *newtree /** New tree */
                   ) {
  /* merge this with tm_reinit? */
  int i, j;

  /* free P matrices */
  for (i = 0; i < mod->tree->nnodes; i++) {
    for (j = 0; j < mod->nratecats; j++)
      if (mod->P[i][j] != NULL) mm_free(mod->P[i][j]);
    sfree(mod->P[i]);
  }

  if (mod->rate_matrix_param_row != NULL) {
    tm_free_rmp(mod);             /* necessary because parameter indices
				     can change */
    tr_free(mod->tree);
    mod->tree = newtree;
    tm_init_rmp(mod);
  } else {
    tr_free(mod->tree);
    mod->tree = newtree;
  }

  /* realloc P matrices */
  mod->P = srealloc(mod->P, mod->tree->nnodes * sizeof(void**));
  for (i = 0; i < mod->tree->nnodes; i++) {
    mod->P[i] = smalloc(mod->nratecats * sizeof(MarkovMatrix*));
    for (j = 0; j < mod->nratecats; j++) mod->P[i][j] = NULL;
  }
}

/* Set branches to be ignored in likelihood calculation and parameter
   estimation.  Argument 'ignore_branches' should be a list of Strings
   indicating nodes in the tree and the branches leading to those
   nodes. */
void tm_set_ignore_branches(TreeModel *mod, List *ignore_branches) {
  int j;
  if (mod->ignore_branch != NULL)
    die("ERROR tm_set_ignore_branches: mod->ignore_branch is not NULL\n");
  mod->ignore_branch = smalloc(mod->tree->nnodes * sizeof(int));
  for (j = 0; j < mod->tree->nnodes; j++) 
    mod->ignore_branch[j] = FALSE;
  for (j = 0; j < lst_size(ignore_branches); j++) {
    String *s = lst_get_ptr(ignore_branches, j);
    TreeNode *n  = tr_get_node(mod->tree, s->chars);
    if (n == NULL)
      die("ERROR: no node named '%s'.\n", s->chars);
    mod->ignore_branch[n->id] = TRUE;
  }
}

AltSubstMod *tm_new_alt_subst_mod(subst_mod_type subst_mod,
                                  Vector *backgd_freqs, 
                                  MarkovMatrix *rate_matrix) {
  AltSubstMod *am = (AltSubstMod*)smalloc(sizeof(AltSubstMod));
  am->subst_mod = subst_mod;
  am->backgd_freqs = backgd_freqs;
  am->rate_matrix = rate_matrix;
  am->separate_model = -1;
  am->ratematrix_idx = -1;
  am->backgd_idx = -1;
  am->selection_idx = -1;
  am->bgc_idx = -1;
  am->separate_model = 1;
  am->selection = am->bgc = 0.0;
  am->param_list = NULL;
  am->noopt_arg = NULL;
  am->defString = NULL;
  am->share_sel = am->share_bgc = NULL;
  return am;
}

void tm_free_alt_subst_mod(AltSubstMod *am) {
  int i;
  if (am->backgd_freqs != NULL)
    vec_free(am->backgd_freqs);
  if (am->rate_matrix != NULL)
    mm_free(am->rate_matrix);
  if (am->param_list != NULL) {
    for (i = 0; i < lst_size(am->param_list); i++) 
      str_free(lst_get_ptr(am->param_list, i));
    lst_free(am->param_list);
  }
  str_free(am->defString);
  if (am->noopt_arg != NULL)
    str_free(am->noopt_arg);
  sfree(am);
}


//remove and free all lineage-specific models
//note: tm->tree is accessed so cannot have already freed
void tm_free_alt_subst_mods(TreeModel *tm) {
  int i;
  if (tm->alt_subst_mods != NULL) {
    for (i=0; i<lst_size(tm->alt_subst_mods); i++) 
      tm_free_alt_subst_mod(lst_get_ptr(tm->alt_subst_mods, i));
    lst_free(tm->alt_subst_mods);
    tm->alt_subst_mods = NULL;
  }
  if (tm->alt_subst_mods_ptr != NULL) {
    for (i=0; i < tm->tree->nnodes; i++)
      sfree(tm->alt_subst_mods_ptr[i]);
    sfree(tm->alt_subst_mods_ptr);
    tm->alt_subst_mods_ptr = NULL;
  }
}


void tm_variance(FILE *outfile, TreeModel *mod, MSA *msa, Vector *allParams, 
		 int cat) {
  double delta=1.0e-6, origParam, origLike, like1, like2, var, sd;
  int idx;
  Vector *optParams;
  
  int nParam=0;
  for (idx=0; idx < allParams->size; idx++) 
    if (mod->param_map[idx] >= 0)
      nParam++;
  optParams = vec_new(nParam);
  nParam=0;
  for (idx=0; idx<allParams->size; idx++) 
    if (mod->param_map[idx] >= 0)
      vec_set(optParams, nParam++, vec_get(allParams, idx));

  tm_unpack_params(mod, optParams, -1);
  origLike = tl_compute_log_likelihood(mod, msa, NULL, NULL, cat, NULL);
  for (idx=0; idx < optParams->size; idx++) {
    origParam = vec_get(optParams, idx);
    vec_set(optParams, idx, origParam + 2*delta);
    tm_unpack_params(mod, optParams, -1);
    like1 = tl_compute_log_likelihood(mod, msa, NULL, NULL, cat, NULL);
    vec_set(optParams, idx, origParam + delta);
    tm_unpack_params(mod, optParams, -1);
    like2 = tl_compute_log_likelihood(mod, msa, NULL, NULL, cat, NULL);
    var = -(delta*delta)/(like1 - 2*like2 + origLike);
    sd = sqrt(var);
    fprintf(outfile, "%f\t%e\t%f\t%f\n", origParam, var, origParam - 1.96*sd, origParam + 1.96*sd);
    vec_set(optParams, idx, origParam);
  }
  tm_unpack_params(mod, optParams, -1);
  vec_free(optParams);
}


int tm_node_is_reversible(TreeModel *tm, TreeNode *node) {
  AltSubstMod *altmod;
  int mainmod_is_reversible=-1, i;
  if (tm->alt_subst_mods_ptr == NULL)
    return subst_mod_is_reversible(tm->subst_mod);
  for (i=0; i < tm->nratecats; i++) {
    altmod = tm->alt_subst_mods_ptr[node->id][i];
    if (altmod == NULL) {
      if (mainmod_is_reversible == -1)
	mainmod_is_reversible = subst_mod_is_reversible(tm->subst_mod);
      if (mainmod_is_reversible == 0) return 0;
    } else {
      if (altmod->bgc_idx >= 0 || !subst_mod_is_reversible(altmod->subst_mod))
	return 0;
    }
  }
  return 1;
}

int tm_is_reversible(TreeModel *tm) {
  int i;
  if (subst_mod_is_reversible(tm->subst_mod) == 0) return 0;
  if (tm->alt_subst_mods == NULL) return 1;
  for (i=0; i < lst_size(tm->alt_subst_mods); i++) {
    AltSubstMod *altmod = lst_get_ptr(tm->alt_subst_mods, i);
    if (subst_mod_is_reversible(altmod->subst_mod)==0) return 0;
    if (altmod->bgc_idx >= 0) return 0;
  }
  return 1;
} 


 void tm_site_model_set_ml_weights(TreeModel *mod, Vector *params, double *counts) {
   double *c=NULL, denom;
   int i;
   if (mod->nratecats == 8) {
     double bgcsum = 0, nobgcsum=0;
     c = smalloc(4*sizeof(double));
     for (i=0; i < 4; i++) {
       c[i] = counts[i] + counts[i+4];
       bgcsum += counts[i+4];
       nobgcsum += counts[i];
     }
     vec_set(params, mod->ratevar_idx + 2, bgcsum/nobgcsum);
   } else if (mod->nratecats == 4)
     c = counts;
   else die("tm_siteMod_set_ml_weights got nratecats=%i\n", mod->nratecats);
   
   denom = (c[2]+c[3])*(c[0]+c[1]+c[2]+c[3]);
   vec_set(params, mod->ratevar_idx, (c[0]+c[2])*(c[0]+c[1])/denom);
   vec_set(params, mod->ratevar_idx+1, (c[1]+c[3])*(c[0]+c[1])/denom);
   if (mod->nratecats == 8) sfree(c);
}


/* Helper function for tm_setup_site_model below.
   Assumes that there is at most one bgc parameter which only applies to certain
   foreground branches, and that it has the limits [0,].
 */
void tm_setup_site_model_func(TreeModel *mod, int ncat, const char *foreground,
			      double *weights, int *backgd_sel_param,
			      int *foregd_sel_param, int *have_bgc, 
			      double *init_sel_param, double initBgc,
			      int *sel_param_opt, char **sel_param_limits) {
  int i, j, *donefore, *doneback, *selmod, bgcmod=-1, fore, cat, fore1, cat1, selpar, dobgc;
  TreeNode *n;
  String *tempstr=str_new(1000);
  char tempch[10000];
  List *foreground_nodes;
  List *rateconsts, *freq;
  AltSubstMod *altmod;

  if (mod->alt_subst_mods != NULL)
    tm_free_alt_subst_mods(mod);

  rateconsts = lst_new_dbl(ncat);
  freq = lst_new_dbl(ncat);
  for (i=0; i < ncat; i++) {
    lst_push_dbl(rateconsts, 1.0);
    lst_push_dbl(freq, weights[i]);
  }
  tm_reinit(mod, mod->subst_mod, ncat, 0.0, rateconsts, freq);
  lst_free(rateconsts);
  lst_free(freq);

  if (mod->selection != 0.0 && mod->selection_idx >= 0) {
    tm_unapply_selection_bgc(mod->rate_matrix, mod->selection, 0.0);
    mod->selection = 0.0;
  }
  mod->selection = 0.0;
  mod->selection_idx = -1;
  mod->site_model = TRUE;  // this is mainly used to change the parameterization of freqK from the default way it is done when empirical_rates=TRUE
  
  foreground_nodes = lst_new_ptr(2);
  tr_get_labelled_nodes(mod->tree, foreground, foreground_nodes);
  if (lst_size(foreground_nodes)==0) {  //foreground must be node name
    n = tr_get_node(mod->tree, foreground);
    if (n == NULL) 
      die("tm_setup_site_model: no nodes or labels with name %s", foreground);
    lst_push_ptr(foreground_nodes, n);
  }
  //need to give label "backgd" to all nodes not in foreground
  for (i=0; i < mod->tree->nnodes; i++) {
    n = lst_get_ptr(mod->tree->nodes, i);
    for (j=0; j < lst_size(foreground_nodes); j++) 
      if (lst_get_ptr(foreground_nodes, j) == n) break;
    if (j == lst_size(foreground_nodes))
      tr_label(n, "backgd");
  }

  donefore = smalloc(ncat * sizeof(int));
  doneback = smalloc(ncat * sizeof(int));
  for (cat=0; cat < ncat; cat++) donefore[cat] = doneback[cat] = 0;

  // main model has selection=0, not optimized, and bgc=0 (as bgc is not allowed in main model)
  // now see which categories this covers (if any- may end up a "dummy" model, which won't be too inefficient unless we are optimizing rate matrix params or backgd frequencies)
  for (cat=0; cat < ncat; cat++) {
    if (sel_param_opt[backgd_sel_param[cat]]==0 &&
	init_sel_param[backgd_sel_param[cat]] == 0.0) 
      doneback[cat] = 1;
    if (sel_param_opt[foregd_sel_param[cat]]==0 &&
	init_sel_param[foregd_sel_param[cat]] == 0.0 &&
	have_bgc[cat] == 0) 
      donefore[cat] = 1;
  }
  
  selmod = smalloc(ncat*2*sizeof(int));
  for (cat=0; cat < ncat*2; cat++) selmod[cat] = -1;
  bgcmod = -1;

  //now add alt models as necessary
  for (cat=0; cat < ncat; cat++) {
    for (fore=0; fore <= 1; fore++) {
      if (fore) {
	if (donefore[cat]) continue;
	selpar = foregd_sel_param[cat];
	dobgc = have_bgc[cat];
      } else {
	if (doneback[cat]) continue;
	selpar = backgd_sel_param[cat];
	dobgc = 0;
      }
      /*      printf("cat %i fore %i has new altmod %i %i\n", cat, fore,
	      selpar, dobgc);*/
      sprintf(tempch, "%s#%i", fore ? foreground : "backgd", cat);
      str_cpy_charstr(tempstr, tempch);
      //check for other models that it may apply to
      for (cat1=cat; cat1 < ncat; cat1++) {
	for (fore1=(cat1==cat ? fore + 1 : 0); fore1 <= 1; fore1++) {
	  if (fore1 && donefore[cat1]) continue;
	  if (!fore1 && doneback[cat1]) continue;
	  if (dobgc && (fore1==0 || have_bgc[cat1]==0)) continue;
	  if (!dobgc && fore1==1 && have_bgc[cat1]) continue;
	  if (fore1 && foregd_sel_param[cat1] != selpar) continue;
	  if (!fore1 && backgd_sel_param[cat1] != selpar) continue;
	  sprintf(tempch, ",%s#%i", fore1 ? foreground : "backgd", cat1);
	  str_append_charstr(tempstr, tempch);
	  if (!fore1) doneback[cat1] = 1;
	  else donefore[cat1] = 1;
	}
      }
      // now figure out optimization string
      str_append_charstr(tempstr, ":");
      if (dobgc && bgcmod == -1) {
	str_append_charstr(tempstr, "bgc[0,]");
	bgcmod = mod->alt_subst_mods == NULL ? 1 : lst_size(mod->alt_subst_mods)+1;
      }
      else if (dobgc) {
	sprintf(tempch, "bgc#%i", bgcmod);
	str_append_charstr(tempstr, tempch);
      }

      if (sel_param_opt[selpar]) {
	if (dobgc) str_append_charstr(tempstr, ",");
	if (selmod[selpar] != -1) {
	  sprintf(tempch, "sel#%i", selmod[selpar]);
	  str_append_charstr(tempstr, tempch);
	} else {
	  str_append_charstr(tempstr, "sel");
	  if (sel_param_limits[selpar] != NULL) 
	    str_append_charstr(tempstr, sel_param_limits[selpar]);
	  selmod[selpar] = mod->alt_subst_mods==NULL ? 1 : (lst_size(mod->alt_subst_mods)+1);
	}
      } else if (init_sel_param[selpar] != 0.0) {
	  str_append_charstr(tempstr, ":sel");
      }
      tm_add_alt_mod(mod, tempstr);
      altmod = lst_get_ptr(mod->alt_subst_mods, lst_size(mod->alt_subst_mods)-1);
      altmod->selection = init_sel_param[selpar];
      if (sel_param_opt[selpar] || init_sel_param[selpar] != 0.0)
	altmod->selection_idx = 0;
      altmod->bgc = (dobgc ? initBgc : 0.0);
      tm_apply_selection_bgc(altmod->rate_matrix, altmod->selection, altmod->bgc);
    }
  }
  str_free(tempstr);
  sfree(selmod);
  sfree(donefore);
  sfree(doneback);
}


/* set up tree model to use site model.  foreground is a branch name or label giving foreground branch.  if bgc==TRUE then there will be 8 site categories, otherwise there will be 4.  The four categories correspond to:
cat  background_sel foreground_sel   freq
0      sel0           sel0           w0/(w0+w1+1)
1      sel1           sel1           w1/(w0+w1+1)
2      sel0           sel2           w0/((w0+w1+1)*(w0+w1))
3      sel1           sel2           w1/((w0+w1+1)*(w0+w1))
Here, sel0 <= 0 and sel1=0.  If alt_hypothesis, then sel2>=0, otherwise sel2= 0.
If bgc==1, then the four categories are repeated with and without bgc in the
foreground branch, and one extra weight parameter, b, is used, such that
p(bgc)=b/(1+b).  
If bgc > 1, then bgc is always used in the foreground branch; there are only
four categories.
In all cases, the variable mod->site_model is turned on.  This sets
up parameterization of the category frequencies as described above.*/
void tm_setup_site_model(TreeModel *mod, const char *foreground, int bgc, 
			 int alt_hypothesis, double selNeg, double selPos,
			 double initBgc, double *initWeights) {
  int nratecats, i;
  double freq[8];
  double param[3] = {5.0, 1.0, 0.5};  //init weight params if initWeights not provided;
  double bgc_freq=0.0;
  int backgd_sel_param[8], foregd_sel_param[8], have_bgc[8], sel_param_opt[3];
  double init_sel_param[3];
  char **sel_param_limits;
  sel_param_limits = smalloc(3 * sizeof(char*));  

  if (initWeights != NULL) {
    param[0] = initWeights[0];
    param[1] = initWeights[1];
    if (bgc==1) param[2] = initWeights[2];
  }

  if (bgc==1) nratecats = 8;
  else nratecats = 4;
  if (bgc==1) bgc_freq = param[2]/(param[2]+1.0);
  freq[0] = param[0]/(param[0]+param[1]+1.0) * (bgc==1 ? (1.0-bgc_freq) : 1.0);
  freq[1] = param[1]/(param[0]+param[1]+1.0) * (bgc==1 ? (1.0-bgc_freq) : 1.0);
  freq[2] = param[0]/((param[0]+param[1])*(param[0]+param[1]+1.0)) * (bgc==1 ? (1.0-bgc_freq) : 1.0);
  freq[3] = param[1]/((param[0]+param[1])*(param[0]+param[1]+1.0)) * (bgc==1 ? (1.0-bgc_freq) : 1.0);
  if (bgc==1) {
    freq[4] = param[0]/(param[0]+param[1]+1.0)*bgc_freq;
    freq[5] = param[1]/(param[0]+param[1]+1.0)*bgc_freq;
    freq[6] = param[0]/((param[0]+param[1])*(param[0]+param[1]+1.0))*bgc_freq;
    freq[7] = param[1]/((param[0]+param[1])*(param[0]+param[1]+1.0))*bgc_freq;
  }

  backgd_sel_param[0] = 0;  //sel neg
  backgd_sel_param[1] = 1;  //sel neutral
  backgd_sel_param[2] = 0;
  backgd_sel_param[3] = 1;
  foregd_sel_param[0] = 0;
  foregd_sel_param[1] = 1;
  foregd_sel_param[2] = alt_hypothesis ? 2 : 1;
  foregd_sel_param[3] = alt_hypothesis ? 2 : 1;
  if (nratecats == 8) {
    for (i=0; i < 4; i++) {
      backgd_sel_param[4+i] = backgd_sel_param[i];
      foregd_sel_param[4+i] = foregd_sel_param[i];
    }
  }
  if (bgc==1) {
    for (i=0; i < nratecats; i++) have_bgc[i] = (i >= 4);
  } else if (bgc > 1) {
    for (i=0; i < nratecats; i++) have_bgc[i] = 1;
  } else {
    for (i=0; i < nratecats; i++) have_bgc[i] = 0;
  }
  init_sel_param[0] = selNeg;
  init_sel_param[1] = 0.0;
  init_sel_param[2] = selPos;  //will not be used if alt_hypothesis == FALSE

  sel_param_opt[0] = 1;
  sel_param_opt[1] = 0;
  sel_param_opt[2] = 1;
  
  sel_param_limits[0] = copy_charstr("[,0]");
  sel_param_limits[1] = NULL;
  sel_param_limits[2] = copy_charstr("[0,]");

  tm_setup_site_model_func(mod, nratecats, foreground, freq, 
			   backgd_sel_param, foregd_sel_param, have_bgc,
			   init_sel_param, initBgc,
			   sel_param_opt, sel_param_limits);

  for (i=0; i < 3; i++)
    if (sel_param_limits[i] != NULL) sfree(sel_param_limits[i]);
  sfree(sel_param_limits);
}


/* 
   Also: we probably want noncoding versions of these as well.
 */
List *tm_setup_bgc_model_hmm(TreeModel *mod, const char *foreground,
			     double selNeg, double selPos,
			     double initBgc, double *initWeights) {
  List *modlist = lst_new_ptr(2), *templst = lst_new_ptr(5);
  TreeModel *mod0, *mod1;
  AltSubstMod *altmod0, *altmod1;
  int i, j, k, numpar;
  String *tempstr, *node1;

  if (!subst_mod_is_codon_model(mod->subst_mod))
    die("noncoding version of bgc model not implemented yet\n");
  mod0 = tm_create_copy(mod);

  /* for now, let's just set the defaults that we want; may want to customize at some point.
   */
  mod0->estimate_branchlens = TM_SCALE_ONLY;
  mod0->scale = 1.0;
  mod0->noopt_arg = str_new_charstr("backgd,ratematrix");
  mod0->scale_during_opt = 1;

  // mod0 has no bgc
  tm_setup_site_model(mod0, foreground, 0, 1, selNeg, selPos, initBgc, initWeights);
  numpar = tm_setup_params(mod0, 0);
  lst_push_ptr(modlist, mod0);


  mod1 = tm_create_copy(mod);
  tm_setup_site_model(mod1, foreground, 2, 1, selNeg, selPos, initBgc, initWeights);
  
  //setup parameters for mod0, then fix bgc_idx in mod1; it has all the parameters.
  
  mod1->scale_idx = mod0->scale_idx;
  mod1->bl_idx = mod0->bl_idx;
  mod1->ratematrix_idx = mod0->ratematrix_idx;
  mod1->backgd_idx = mod0->backgd_idx;
  mod1->ratevar_idx = mod0->ratevar_idx;
  mod1->selection_idx = mod0->selection_idx;

  for (i=0; i < lst_size(mod1->alt_subst_mods); i++) {
    altmod1 = lst_get_ptr(mod1->alt_subst_mods, i);
    altmod1->selection_idx = -1;

    //get the name of a node/cat that this altmod applies to
    str_split(altmod1->defString, ":", templst);
    tempstr = str_dup(lst_get_ptr(templst, 0));
    lst_free_strings(templst);
    str_split(tempstr, ",", templst);
    str_free(tempstr);
    node1 = str_dup(lst_get_ptr(templst, 0));
    lst_free_strings(templst);

    //set bgc_idx if this altmod has bgc
    if (altmod1->bgc_idx >= 0)   
      altmod1->bgc_idx = numpar;

    for (j=0; j < lst_size(mod0->alt_subst_mods); j++) {
      altmod0 = lst_get_ptr(mod0->alt_subst_mods, j);

      //get the name of a node/cat that this altmod applies to
      str_split(altmod0->defString, ":", templst);
      tempstr = str_dup(lst_get_ptr(templst, 0));
      lst_free_strings(templst);
      str_split(tempstr, ",", templst);
      str_free(tempstr);

      for (k=0; k < lst_size(templst); k++)
	if (str_equals(node1, lst_get_ptr(templst, k)))
	  break;
      if (k < lst_size(templst)) {
	if (altmod1->selection_idx != -1) 
	  die("ERROR: got multiple matches in tm_setup_bgc_hmm\n");  //this would imply a bug; it's a note to myself
	altmod1->selection_idx = altmod0->selection_idx;
	altmod1->ratematrix_idx = altmod0->ratematrix_idx;
	altmod1->backgd_idx = altmod0->backgd_idx;
      }
      lst_free_strings(templst);
    }
    str_free(node1);
    if (altmod1->selection_idx == -1)
      die("ERROR: did not find a match in tm_setup_bgc_hmm\n"); //ditto above
  }
  lst_free(templst);
  lst_push_ptr(modlist, mod1);
  return modlist;
}

