# taucs_chsolve

solve a linear sparse (s.p.d.) system given the Cholesky factors

## Calling Sequence

    [x] = taucs_chsolve(C_ptr, b [, A])

## Arguments

C_ptr

  a pointer to a handle of the Cholesky factors (C,p with A(p,p)=CC')

b

  a real column vector or a matrix (multiple rhs)

x

  a real column vector or a matrix in case of multiple rhs ( x(:,i) is solution of A x(:,i) = b(:,i))

A

  (optional) the real s.p.d. matrix A (to use for iterative refinement step)

## Description

This function must be used in conjonction with taucs_chfact which computes the Cholesky factorization of a sparse real s.p.d. matrix. When the matrix `A` is provided, one iterative refinement step is done (the refined solution is accepted if it improves the 2-norm of the residual `Ax-b`).

Like in taucs_chfact the matrix A may be provided either in its complete form (that is with the lower triangle also) or only with its upper triangle.

## Examples

see the example section of taucs_chfact

## See Also

- taucs_chfact
- taucs_chdel
- taucs_chinfo
- taucs_chget
- cond2sp