GAP(1)

NAME
GAP - Groups, Algorithms, and Programming

SYNTAX
gap [ -b ] [ -e ] [ -q ] [ -m mem ] [ -g ] [ -n ] [ -x width ] [ -y height ] [ -l libname ] [ -h docname ] [ -z freq ] [ file ... ]

DESCRIPTION
The command above initiates a session with the group theory system GAP. Expressions are read from standard input and the results are produced on the standard output as each input expression is evaluated. GAP's main purpose are group theory calculations in finitely presented groups, permutation groups, polycyclicly presented groups, representations and characters. It also supports arbitrary length integers and rationals, cyclotomic fields, finite fields, lists, sets, records, and a programming language of Pascal type. Some share libraries, e.g. GRAPE for Graphs, are available. The whole manual is accessible as on-line help. After starting GAP, type "?Help" to see a description of the on-line help system. To get more information about GAP look at the chapter "About GAP", to leave GAP, type "quit;" or "control-D".

WARNING
The information in this man page is an extract from the full documentation of GAP, and is limited to the meaning of the options.

OPTIONS

-b
This option tells GAP to surpress the banner.  That means that GAP
    immediately prints the prompt. This is useful when you get tired of the banner after a while.

-e  This option tells GAP not to quit on "control-D".

-q  This options tells GAP to be quiet. This means that GAP does not display the banner and the prompts "gap>". This is useful if you want to run GAP as a filter with input and output redirection and want to avoid the banner and the prompts clobber the output file.

-m mem
    This option tells GAP to allocate mem bytes at startup time. If the last character of mem is k or K, it is taken in KBytes and if the last character is m or M, mem is taken in MBytes.

-g  This option tells GAP to print an information message every time a garbage collection is performed. See also "Features of GAP for UNIX" in the GAP manual.

-r  This option tells GAP not to read the user's .gaprc file.

-n  This option tells GAP to disable the line editing and history (see also "Line Editing" in the GAP manual). You may want to do this if the command line editing is incompatible with another program that is used to run GAP.

-x width
    With this option you can tell GAP how long lines are. GAP uses this value to decide when to split long lines. The default value is 80. See also "SizeScreen" in the GAP manual.

-y height
    With this option you can tell GAP how many lines your screen has. GAP uses this value to decide after how many lines of on-line help it should display "-- <space> for more --". See also "SizeScreen" in the GAP manual.

-l libname
    This option tells GAP that the library of GAP functions is in the directory libname. Per default libname is "lib/". GAP will read the file "libname/init.g" during startup. If GAP cannot find this file it will print a warning. See also "Features of GAP for UNIX" in the GAP manual.

-h docname
    This option tells GAP that the on-line documenation for GAP is in the directory docname. Per default docname is obtained by replacing "lib" in libname with "doc". If you get a warning when trying to use the help system check docname. See also "Features of GAP for UNIX" in the GAP manual.

-z freq
    The option is only available under MS-DOS. GAP for MS-DOS checks in regular intervals whether the user has entered "control-Z" or "alternate-C" to interrupt an ongoing computation. Under MS-DOS this requires reading the keyboard status, which is rather expensive. Therefore GAP only reads the keyboard status ever freq-th time. The default is 20. With this option this value can be changed. Lower values make GAP more responsive to interrupts, higher values make GAP a little bit faster.

files
    Any additional parameters are assumed to be files, which are read in after initialising the library.

FILES

~/.gaprc
if this file exists,  it is read in before the files specified on the
    command line are read. If -r option was used this is file is not read.

AUTHORS
GAP is a project of the 'Lehrstuhl D fuer Mathematik' of the 'Rheinisch-Westfaelische Technische Hochschule Aachen'. If you are a new GAP user we ask you to notify us, e.g., by sending a short e-mail message to "gap@Math.RWTH-Aachen.DE". The simple reason, on top of our curiosity, is that as anybody else in an academic environment we have from time to time to prove that we are doing meaningful work. We, the developers of GAP, have also established a discussion list, the GAP forum, where interested users can discuss GAP related topics by e-mail. In particular this forum is for questions about GAP, general comments, bug reports, and maybe bug fixes. For information on how to subscribe to this forum, see the README file. If you have technical or installation problems, we suggest that you write to "gap-trouble@Math.RWTH-Aachen.DE" instead of the GAP forum, as such discussions are usually not very interesting for a larger audience. Your e-mail message will be read by several people here, and we shall try to provide support.

COPYRIGHT
GAP is given away under the conditions that have always been in use between mathematicians, i.e. in particular completely in source and free of charge. For further information see the README file.