This chapter describes the GAP package LRS4GAP. This package implements a Linear Programming solver for GAP using the arbitrary precision rational arithmetic solver lrs by David Avis.
If you are viewing this with on-line help, type:
gap> ?LRS4GAP package
to see the functions provided by the LRS4GAP package.
The LRS4GAP package may be installed in the GAP root package directory, or using a separate archive, for example, for an update or an installation in a non-default location (see Reference: GAP Root Directories).
Below we describe the installation procedure for the .tar.gz archive format. Installation using other archive formats is performed in a similar way.
To install the LRS4GAP package, unpack the archive file, which should have a name of form LRS4GAP-XXX.tar.gz for some version number XXX, by typing
gzip -dc LRS4GAP-XXX.tar.gz | tar xpv
It may be unpacked in one of the following locations:
in the pkg directory of your GAP 4 installation;
or in a directory named .gap/pkg in your home directory (to be added to the GAP root directory unless GAP is started with -r option);
or in a directory named pkg in another directory of your choice (e.g. in the directory mygap in your home directory).
In the latter case one one must start GAP with the -l option, e.g. if your private pkg directory is a subdirectory of mygap in your home directory you might type:
gap -l ";myhomedir/mygap"
where myhomedir is the path to your home directory, which (since GAP 4.3) may be replaced by a tilde (the empty path before the semicolon is filled in by the default path of the GAP 4 home directory).
To use the LRS4GAP Package you have to request it explicitly. This is done by calling LoadPackage (Reference: LoadPackage):
gap> LoadPackage("LRS4GAP"); ---------------------------------------------------------------- Loading LRS4GAP 0.1 by Gábor P. Nagy (http://www.math.u-szeged.hu/~nagyg) For help, type: ?LRS4GAP package ---------------------------------------------------------------- true
If GAP cannot find a working binary then it does not load the package and returns fail.
If you want to load the LRS4GAP package by default, you can put the LoadPackage command into your gaprc file (see Section Reference: The gap.ini and gaprc files).
After unpacking the archive, go to the newly created LRS4GAP/src directory and call
make clean make lrs
This will compile the binary lrs, which you have to copy in the appropriate directory of bin.
You can run tests for the package by
gap> Test(Filename(DirectoriesPackageLibrary("LRS4GAP"),"../tst/testall.tst"));
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