Customizations of the &AtlasRep; Package
Installing the &AtlasRep; Package

To install the package, unpack the archive file in a directory in the pkg directory of your local copy of &GAP; 4. This might be the pkg directory of the &GAP; 4 root directory, see for details. It is however also possible to keep an additional pkg directory somewhere else, see Section . The latter possibility must be chosen if you do not have write access to the &GAP; root directory.

If it is likely that you will work offline, it makes sense to install the starter archive that can be downloaded from the package's homepage.

The package consists entirely of &GAP; code, no external binaries need to be compiled for the package itself. However, if the &GAP; package `IO` IO package is used to access remote data files (see Section ) then its external binary must be available.

After unpacking the package archive, the write permissions for those directories should be checked into which users will download files. Every user can customize these paths via a user preference, see Section , the defaults are the subdirectories data* of the package directory. The recommended permissions under UNIX for the default directories are set as follows.

you@unix> chmod 1777 atlasrep/data* you@unix> ls -ld atlasrep/data* drwxrwxrwt 3 you you 1024 Apr 12 12:34 dataext drwxrwxrwt 3 you you 1024 Apr 12 12:34 datagens drwxrwxrwt 3 you you 1024 Apr 12 12:34 datapkg drwxrwxrwt 3 you you 1024 Apr 12 12:34 dataword

<#Include Label="[1]{testinst.g}">

PDF, HTML, and text versions of the package manual are available in the doc directory of the package.

User Preferences of the &AtlasRep; Package

This section describes global parameters for which it might make sense to change their defaults, using &GAP;'s user preferences (see ).

Is access to remote data allowed (see Section )? If yes then also the following parameters are of interest.

From where can the data be fetched (see Section )?
Where are local copies of these data stored (see Section )?
How are these data transfered (see Section )?
Shall files be compressed after they have been downloaded (see Section )?
The following parameters influence reading and writing of local files.

What shall actually happen when data are requested by the interface functions (see Section )?
If the value of the user preference FileAccessFunctions contains "direct access to a local server", what is its path (see Section )?
Shall focus on small runtime or on small space when reading &MeatAxe; text files (see Section )?
Which kind of headers shall create (see Section )?
Shall interpret permutation matrices more as permutations (mode 2) or as matrices (mode 1 or 6) (see Section )?
Shall the default for be to write binary files of zero-based or one-based permutations (see Section )?
Which function is used by for printing to the screen (see Section )?
How does mark data that do not belong to the core database (see Section )?
Shall debug messages be printed when local data files are read (see Section )?
<#Include Label="AtlasRepAccessRemoteFiles"> <#Include Label="AtlasRepDataDirectory"> <#Include Label="AtlasRepTOCData"> <#Include Label="FileTransferTool"> <#Include Label="CompressDownloadedMeatAxeFiles"> <#Include Label="FileAccessFunctions"> <#Include Label="AtlasRepLocalServerPath"> <#Include Label="HowToReadMeatAxeTextFiles"> <#Include Label="WriteHeaderFormatOfMeatAxeFiles"> <#Include Label="WriteMeatAxeFilesOfMode2"> <#Include Label="BaseOfMeatAxePermutation"> <#Include Label="DisplayFunction"> <#Include Label="AtlasRepMarkNonCoreData"> <#Include Label="DebugFileLoading">

Web Contents for the &AtlasRep; Package

The &ATLASREPHOME; home page of the &AtlasRep; package provides

package archives,
introductory package information,
the current table of contents of core data in the file atlasprm.json &ATLASREPHOME;/atlasprm.json of the package, cf. ,
the list of changes of remote core data files &ATLASREPHOME;/htm/data/changes.htm,
a starter archive &ATLASREPHOME;/atlasrepdata.tar.gz containing many small representations and programs, and
an overview of the core data &ATLASREPHOME;/htm/data in a similar format as the information shown by the function of the package; more details can be found on the home page of the &ATLAS; of Group Representations &ATLASSERVER;.
Extending the &ATLAS; Database

Users who have computed new representations that might be interesting for inclusion into the &ATLAS; of Group representations can send the data in question to &WILSONMAIL;.

It is also possible to make additional representations and programs accessible for the &GAP; interface, and to use these private data in the same way as the core data. See Chapter for details.