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# 73 Installing GAP

### Sections

1. Installation Overview
2. Get the Archives
3. Unpacking
4. Compilation
5. Test of the installation
6. Packages
7. Finish Installation and Cleanup
8. The Documentation
9. If Things Go Wrong
10. Known Problems of the Configure Process
11. Problems on Particular Systems
12. Optimization and Compiler Options
13. Porting GAP
14. GAP for Macintosh OS X
15. GAP for MacOS
16. Installation of GAP for MacOS
17. Expert Windows installation
18. Copyrights

GAP runs on a large number of different operating systems. It behaves slightly different on each of those. This chapter describes the behaviour of GAP, the installation, and the options on some of those operating systems.

Currently it contains instructions for UNIX (which includes the popular variant Linux), for Apple Macintosh computers under OS X (see GAP for Macintosh OS X) as well under the ``classic'' MacOS (see GAP for MacOS), and finally for Windows.

For other systems the section Porting GAP gives hints how to approach such a port.

## 73.1 Installation Overview

To permit compatibility over a wide range of operating systems, the installation of GAP might differ from what you are accustomed to for you particular operating system. In particular, there is no ``Installer'' program.

Installing the GAP distribution alone takes about 150MB of disk space. The packages add another 100MB. (These are upper limits. Unix is more efficient in storing a large number of small files than Windows.) You also should have at least 64MB of memory to run GAP.

The installation consists of 5 easy steps:

-
  Get the archive(s) suitable for your system

-
  Unpack

-
  Compile (unless a binary has been provided already)

-
  Test the installation

-
  Install packages. (Some packages will only work under Unix and OS X).

Installation will always install the full version of GAP. There is no ``Upgrade'' mode. If you are worried about losing the old version, you can keep an existing installation of GAP in another directory, it will not be overwritten.

Section The Documentation contains information about the manual, where to find and how to print it. Section If Things Go Wrong lists common problems with the installation.

## 73.2 Get the Archives

You can get archives for the GAP distribution from http://www.gap-system.org. As different operating systems use different archive formats, GAP is available in a variety of archives. These archives slightly differ in the treatment of text or binary files. If you get the wrong archive you might get error messages during compilation or not be able to look at text files in an editor.

If you use

Unix
  you can use the `.tar.gz`, `.tar.bz2` or `.zoo` archives.

Macintosh OS X
  you can use the `.tar.gz` or `.zoo` archives (or install the `MacOS` version, see also GAP for Macintosh OS X).

MacOS
  Use the `.zoo` archive. Also make sure you get the `.sit` StuffIt archives for the `unzoo` uncompressor.

Windows
  Use the `-win.zip` or the `.zoo` archives.

Now get the installation archives of the right kind, according to your operating system. You want to get the archives:

`gap4r4p6`
  which contains the main GAP installation

`packages4r4p6`
  which contains GAP packages that provide further functionality

`unzoo`
  Only if you use the `.zoo` archives: Unix and OS X users get the source code `unzoo.c`, MacOS users get the `.sit` archive and Windows users the `.exe` binary.

`htmie4r4p6`
  An alternative version of the HTML manual which uses a nonstandard ``symbol'' font instead of Unicode characters. If you use a webbrowser such as `Internet Explorer` that has difficulties with rendering Unicode correctly, you might want to replace the HTML documentation with this version. (See section The Documentation.)

`xtom4r4p6`
  Contains about 80MB of further tables of marks. (You can always install this later if the need arises.)

Note that starting with release 4.4, the distribution archives for GAP will always contain the most recent bugfix. Thus if you install anew from scratch, you will not need to get any bugfixes.

## 73.3 Unpacking

The concrete act of unpacking will vary slightly, depending on the operating system and the type of archive used.

Unix, OS X
  Under Unix or OS X unpack the archive `gap4r4p6` in whatever place you want GAP to reside. If you use the `.zoo` archive, you will have to compile the `unzoo` program first

      cc -o unzoo -DSYS_IS_UNIX -O unzoo.c
      ./unzoo -x gap4r4p6.zoo

  (If you unpack the archive as `root` user under UNIX, make sure that you issue the command `umask 022` before, to ensure that users will have permissions to read the files.)

MacOS
  if the `.sit` archive did not extract autmatically, click it to force extraction. You will end up with an applications, `unzoo 4.4 PPC`. Now move this applications, as well as the `gap4r4p6.zoo` archive to the Folder in which you want to install GAP. Drag the archive `gap4r4p6.zoo onto the icon of `unzoo 4.4 PPC`. You will get a window with many lines of text output. This process will create a folder `gap4r4` in the current folder.

Windows
  The archive must be extracted to the main directory of the `C:` drive. (If you do not have permissions or sufficient free space to create directories there, see section Expert Windows installation.) If you use the `.zoo` archives we provide move `unzoo.exe` and `gap4r4p6.zoo` in the `C:` directory, open the `MS-DOS` (or `Command Prompt`) window. (You can find this under ``Start/Programs/Accessories''.) In this window issue the commands

      cd c:\
      unzoo -x gap4r4p6.zoo

  (It might be necessary to use upper case letters instead)

  If you prefer to use the `-win.zip` archive use a `ZIP` extractor. Make sure that you specify extraction to the `c:/` folder (with no extra directory name -- the directory is part of the archive) to avoid extraction in a wrong place or in a separate directory. After extraction you can start GAP with the file

      C:\GAP4R4\bin\gapw95.exe

## 73.4 Compilation

For the MacOS and Windows version the unpacking process will already have put binaries in place. Under Unix and OS X you will have to compile (OS X users please see section GAP for Macintosh OS X for information about compilation) such a binary yourself.

Go into the directory `gap4r4` (which you just created by unpacking). Issue the two commands

    ./configure
    make

Both will produce a lot of text output. You should end up with a shell script `bin/gap.sh` which you can use to start GAP. (If you want, you can copy this script later to a directory that is listed in your search path.)

OS X users please note that this script must be started from within the `Terminal` Application. It is not possible to start GAP by clicking this script.

If you get weird error messages from these commands, make sure that you got the Unix version of GAP (i.e. not the `-win.zip` format archive) and that you extracted the archive on the machine on which you compile. Also see section Known Problems of the Configure Process below for further information.

If you use OS X in the ``Panther'' release (version 10.3), you might want to change the call to `make` to

    make COPTS="-fast -mcpu=7450"

on a G4 system or to

    make COPTS="-O3 -mtune=G5 -mcpu=G5 -mpowerpc64"

on a G5 system (please note that the `-fast` compiler option causes problems on a G5 at the time of this writing -- February 2004). Initial tests indicate that this will give you substantially improved performance.

Unless you want to use the same installation of GAP also under Windows or MacOS (not OS X), issue the command

    make removewin

to delete unnecessary files that are Windows-only and only take up about 2MB of space.

## 73.5 Test of the installation

You are now at a point where you can start GAP for the first time. Unix and OS X users type

    ./bin/gap.sh

MacOS users click the Application `GAP 4 PPC` in the `gap4r4` directory, Windows users start

    C:\GAP4R4\bin\gapw95.exe

GAP should start up with its banner and after a little while give you a command prompt `>`.

Try a few commands to see if the compilation succeeded.

    gap> 2 * 3 + 4;
    10
    gap> Factorial( 30 );
    265252859812191058636308480000000
    gap> m11 := Group((1,2,3,4,5,6,7,8,9,10,11),(3,7,11,8)(4,10,5,6));;
    gap> Size( m11 );
    7920
    gap> Length( ConjugacyClasses( m11 ) );
    10
    gap> Factors( 10^42 + 1 );
    #I  IsPrimeInt: probably prime, but not proven: 4458192223320340849
    [ 29, 101, 281, 9901, 226549, 121499449, 4458192223320340849 ]

If you get the error message ```hmm, I cannot find lib/init.g`'' you are likely to have installed only the binary (or on Windows have not installed GAP in the root directory of the `C:` drive).

If GAP starts but you get error messages for the commands you issued, the files in the `lib` directory are likely to be corrupt or incomplete. Make sure that you used the proper archive and that extraction proceeded without errors.

Especially try the command line editing and history facilities, because they are probably the most machine dependent feature of GAP. Enter a few commands and then make sure that ctr-`P` redisplays the last command, that ctr-`E` moves the cursor to the end of the line, that ctr-`B` moves the cursor back one character, and that ctr-`D` deletes single characters. So, after entering the above commands, typing

ctr-`P` ctr-`E` ctr-`B` ctr-`B` ctr-`B` ctr-`B` ctr-`D` `2` return

should give the following lines:

    gap> Factors( 10^42 + 2 );
    #I  IsPrimeInt: probably prime, but not proven: 3145594690908701990242740067
    [ 2, 3, 433, 953, 128400049, 3145594690908701990242740067 ]

If you want to run a more thorough test (this is not required), you can read in a test script that exercises more of GAPs capabilities.

    gap> Read( Filename( DirectoriesLibrary( "tst" ), "testall.g" ) );

The test requires about 60-70MB of memory and runs about 2 minutes on a Pentium III/1 GHz machine. You will get a large number of lines with output about the progress of the tests.

    test file         GAP4stones     time(msec)
    -------------------------------------------
    testing: /home/fac/a/hulpke/gap4/tst/zlattice.tst
    zlattice.tst               0              0
    testing: /home/fac/a/hulpke/gap4/tst/gaussian.tst
    gaussian.tst               0             10
    [ further lines deleted ]

Windows users should note that the MS-DOS/Command Prompt user interface provided by Microsoft might not offer history scrolling or cut and paste with the mouse. See section Expert Windows Installation for a way around this.

## 73.6 Packages

To extract the packages, extract the `package4r4p6` archive in the ``gap4r4/pkg' directory by the same method used to extracted the main archive. (If you use `unzoo` or under MacOS move both the `unzoo` binary and the archive in the `pkg` directory and extract there.)

For packages that consist only of GAP code no further installation is necessary. Some packages however contain external binaries that will require separate compilation. (If you use the MacOS version or Windows you will not be able to use external binaries anyhow any you can skip the rest of this section.) You can skip this compilation now and do it later -- GAP will work fine, just the capabilities of the affected packages won't be available.

In general, each package contains a `README` file that contains information about the package and the necessary installation. Typically the installation for a package consists of changing in the packages directory and issuing the commands `./configure; make` in the packages directory. (This has to be done separately for exery package).

If you have problems with package installations please contact the package authors as listed in the packages `README` file.

## 73.7 Finish Installation and Cleanup

Congratulations, your installation is finished.

Once the installation is complete, we would like to ask you to send us a short note to support@gap-system.org, telling us about the installation. (This is just a courtesy; we like to know how many people are using GAP and get feedback regarding difficulties (hopefully none) that users may have had with installation.)

We also suggest that you subscribe to our `GAP Forum` mailing list; see the GAP web pages for details. Whenever there is a bug fix or new release of GAP this is where it is announced. The `GAP Forum` also deals with user questions of a general nature; bug reports and other problems you have while installing and/or using GAP should be sent to support@gap-system.org.

At this point you can also delete all archive files. (You might want to keep `unzoo` if you used it in case a bugfix will be released.)

The directories `trans`, `small` and `prim` within `gap4r4` contain data libraries. If you are short of disk space you can erase some of them. Similarly, you can erase and any of the GAP package directories in `pkg` that you have decided you don't need, but then of course you will not be able to access these data or packages. (You should do this only if you have diskspace problems as you might find out later that you need certain packages.)

If you are new to GAP, you might want to read through the following two sections for information about the documentation.

## 73.8 The Documentation

The GAP manual is distributed in various ``books''. The standard distribution contains four of them (as well as a comprehensive index). GAP packages (see Chapter GAP Packages and, in particular, Section Loading a GAP Package) provide their own documentation in their own `doc` directories.

All documentation will be available automatically for the online help (see Section Tut:Help in the Tutorial and Chapter The Help System in this manual for more details).

There also is (if installed) an HTML version of some books that can be viewed with an HTML browser, see Changing the Help Viewer. Some of these use unicode characters for mathematical formulae. If your browser is not able to display these (older versions of `Internet Explorer` do not), get the `htmie4r4p6` archive which provides math symbols in a different encoding. (`Mozilla`, `Konqueror` and `Safari` all support unicode characters.)

The manual is also available in `pdf` format. In the full UNIX distribution (`gap4r4p6.zoo`) these files are included in the directory `gap4r4/doc` in the subdirectories `tut` (a beginner's tutorial), `ref` (the reference manual), `prg` (programmer's tutorial), `ext` (programmer's reference) and `new` (new material that might still change in future versions).

If you want to use these manual files with the online help you may check (or make sure) that your system provides some additional software like

`xpdf`
  see http://www.foolabs.com/xpdf/

`xdvi`
  see any of the CTAN sites/mirrors; the main site is: http://www.ctan.org/

  and the mirrors are listed at: http://www.ctan.org/tex-archive/CTAN.sites

  At any of the mirrors the path of the file containing the `xdvi` archive (after the main site name) is `tex-archive/dviware/xdvi/xdvi.tar.gz`.

`acroread`
  see http://www.adobe.com/products/acrobat/readstep.html

As a complete beginner, we suggest you read the tutorial first for an introduction to GAP 4. Then start to use the system with extensive use of the online help system (see Section Tut:Help in the Tutorial and Chapter The Help System in this manual).

If you have experience with GAP 3, it might be still worthwhile to at least glance over the first chapters of the tutorial. You however should read the last chapter of the tutorial, ``Migrating to GAP4''. This chapter gives a summary of changes between GAP 3 and GAP 4 that will affect the user. It also explains a ``compatibility mode'' you may turn on to make GAP 4 behave a bit more like GAP 3.

As some of the manuals are quite large, you should not immediately print them. If you start using GAP it can be helpful to print the tutorial (and probably the first chapters of the reference manual). There is no compelling reason to print the whole of the reference manual, better use the online help which provides useful search features.

## 73.9 If Things Go Wrong

This section lists a few common problems when installing or running GAP and their remedies. Also see the FAQ list on the GAP web pages at http://www.gap-system.org/Info/Faq/faq.html

GAP starts with a warning ```hmm, I cannot find 'lib/init.g'`''.
  You either started only the binary or did not edit the shell script/batch file to give the correct library path. You must start the binary with the command line option `-l` path where path is the path to the GAP home directory. See section Command Line Options in the reference manual.

When starting, GAP produces error messages about undefined variables.
  You might have a `.gaprc` file that was intended for GAP 3 but is not compatible with GAP 4. See section The .gaprc file in chapter Running GAP of the reference manual.

GAP complains: ```corrupted completion file`''.
  Some library files got changed without rebuilding the completion files. This is often a sign that earlier a bugfix was not installed properly or that you changed the library yourself. In the latter case, start GAP with command line option `-N` and see section Completion Files.

GAP stops with an error message ```exceeded the permitted memory`''.
  Your job got bigger than what is permitted by default (256MB). (This is a safety feature to avoid single jobs wrecking a multi-user system.) You can type `return;` to continue, if the error message happens repeatedly you better start the job anew and use the command line option `-o` to set a higher memory limit.

GAP stops with an error message: ```cannot extend the workspace any more`''.
  Your calculation exceeded the available memory. Most likely you asked GAP to do something which required more memory than you have (as listing all elements of S15 for example). You can use the command line option `-g` (see section Command Line Options in the reference manual) to display how much memory GAP uses. If this is below what your machine has available extending the workspace is impossible. Start GAP with more memory or use the `-a` option to pre-allocate initially a large piece of workspace.

GAP is not able to allocate memory above a certain limit
  Being a 32 bit program, GAP currently is unable to use over 4GB of memory. Since the address space also has to keep the operating system, 3GB probably are an upper limit for a GAP workspace.

  Depending on the operating system, it also might be necessary to compile the GAP binary statically (i.e. to include all system libraries) to avoid collisions with system libraries located by default at an address within the workspace. (Under Linux for example, 1GB is a typical limit.) You can compile a static binary using `make static`.

  Windows users also see below for a built-in limit.

`make` complains about not being able to find files in `cnf` or `src` which exist.
  The dates of the new files were not extracted properly (Alpha-OSF machines are prone to this). Call

      touch * cnf/* src/*

  from the main GAP directory (this ought to reset the date of all relevant files to ``now'') and try again.

Recompilation does not actually compile changed files.
  The dates of the new files were not extracted properly. Go in the source directory and `touch` (UNIX command to change date) the new files.

Recompilation fails or the new binary crashes.
  Call `make clean` and restart the `configure` / `make` process completely from scratch. (It is possible that the operating system and/or compiler got upgraded in the meantime and so the existing `.o` files cannot be used any longer.

A calculation runs into an error ``no method found''.
  GAP is not able to execute a certain operation with the given arguments. Besides the possibility of bugs in the library this means two things: Either GAP truly is incapable of coping with this task (the objects might be too complicated for the existing algorithms or there might be no algorithm that can cope with the input). Another possibility is that GAP does not know that the objects have certain nice properties (like being finite) which are required for the available algorithms. See sections ApplicableMethod and KnownPropertiesOfObject.

Problems specific to Windows

Command line editing does not work under Windows.
  The default key commands are UNIX-like. GAP also tries to emulate some of the special keys under Windows, however if the key repeat is set too high, Windows loses parts of the codes for these keys and thus GAP cannot recognize them. Windows98 produces the same scan code for all cursor keys. As GAP does not interface directly with the Windows machinery, there is no known way around this problem. Use the Unix-style cursor commands.

The `^`-key or `"`-key cannot be entered.
  This is a problem if you are running a keyboard driver for some non-english languages. These drivers catch the `^` character to produce the French circumflex accent and do not pass it properly to GAP. No fix is known.

GAP does not start or cannot expand memory
  You will have to edit a registry entry to be able to use more than 127MB of memory. See Expert Windows Installation.

Cut and Paste does not work
  You might want to start GAP under `rxvt` -- see Expert Windows Installation. Also http://www.gap-system.org/Faq/Hardware-OS/hardware-os.html might give a remedy.

You get an error message about the `cygwin1.dll`
  GAP comnes with a version of this dynamic library. If you have another version installed (use ``Find''), delete the older one (and probably copy the newer one in both places).

If all these remedies fail or you encountered a bug please send a mail to support@gap-system.org. Please give:

- a (short, if possible) self-contained excerpt of a GAP session containing both input and output that illustrates your problem (including comments of why you think it is a bug); and

- state the type of machine, operating system, (compiler used, if UNIX/Linux) and version of GAP (for example ``gap4r4p6, fix1'') you are using (the line after the GAP 4 banner starting:

      GAP4, Version: 4...

  when your GAP 4 starts up, supplies the information required).

## 73.10 Known Problems of the Configure Process

If `make` complains ``Do not know how to make xyz'' but xyz is an existing file, it is likely that the dates of the files were not extracted properly (Alpha-OSF machines are prone to this). Call

    touch * cnf/* src/*

from the main GAP directory (this ought to reset the date of all relevant files to ``now'') and try again.

Sometimes the `configure` process does not properly figure out the ``inline'' compiler command. If you get error messages that complain that ``inline'' is unknown, edit the file `config.h` in the `bin/`target`` subdirectory and replace the line

    /* #undef inline */

by

    #define inline

and then try to compile again.

The `configure` script respects compiler settings given in environment variables. However such settings may conflict with the automatic configuration process. If `configure` produces strange error messages about not being able to run the compiler, check whether environment variables that might affect the compilation (in particular `CC`, `LD`, `CFLAGS`, `LDFLAGS` and `C_INCLUDE_PATH`) are set and reset them using `unsetenv`.

Some users reported problems with `make`, while the GNU version `gmake` worked. Thus if problems occur you should try `gmake` instead if it is installed on your machine.

## 73.11 Problems on Particular Systems

The highest levels of optimization of the OSF/4 C compiler `cc` on the Compaq alpha chip make assumptions about the use of pointers which are not valid for GAP, and produce executables that can crash; `-O3` seems to be safe, but `-O4` and `-fast` are not.

On Sun and IRIX systems which are capable of running in 32 or 64 bit modes, it is possible to build a 64 bit version of GAP, but special procedures are needed (and, on Suns, a compiler bug must be circumvented). If you wish to compile on such a system, please send an email to support@gap-system.org.

## 73.12 Optimization and Compiler Options

Because of the large variety of different versions of UNIX and different compilers it is possible that the `configure` process will not chose best possible optimization level, but you might need to tell `make` about it.

If you want to compile GAP with further compiler options (for example specific processor optimizations) you will have to assign them to the variable `COPTS` as in the following example when calling `make`:

    make COPTS=-option

If there are several compiler options or if they contain spaces you might have to enclose them by quotes to avoid depending on the shell you are using.

The `configure` process also introduces some default compiler options. (See the `Makefile` in the `bin` directory for details.) You can eliminate these by assigning the variable `CFLAGS` (which contains the default options and `COPTS`) to the desired list of compiler options in the same way as you would assign `COPTS`.

The recommended C compiler for GAP is the GNU C compiler `gcc`, or a related compiler such as `egcs`. There are two reasons for this recommendation: firstly we use `gcc` in GAP development and so this combination has been far more heavily tested than any other and secondly, we have found that it generally produces code which is faster than that produced by other compilers.

If you do wish to use another compiler, you should remove `config.cache` and `config.status` in the GAP root directory, set the environment variable `CC` to the name of your preferred compiler and then rerun `configure` and `make`. You may have to experiment to determine the best values for `CFLAGS` and/or `COPTS` as described above. Please let us (support@gap-system.org) know the results of your experiments.

## 73.13 Porting GAP

Porting GAP to a new operating system should not be very difficult. However, GAP expects some features from the operating system and the compiler and porting GAP to a system or with a compiler that do not have those features may prove very difficult.

The design of GAP makes it quite portable. GAP consists of a small kernel written in the programming language C and a large library written in the programming language provided by the GAP kernel, which is also called GAP.

Once the kernel has been ported, the library poses no additional problem, because all those functions only need the kernel to work, they need no additional support from the environment.

The kernel itself is separated into a large part that is largely operating system and compiler independent, and one file that contains all the operating system and compiler dependent functions. Usually only this file must be modified to port GAP to a new operating system.

Now let us take a look at the minimal support that GAP needs from the operating system and the machine:

You need enough main memory in your computer. The size of the GAP kernel varies between 1.5 and 2.5 MByte (depending on the machine). The GAP library additionally takes a minimum of 10MByte and the library of functions that GAP loads takes up another 1.5 MByte. So it is clear that at least 16 MByte of main memory are required to do any serious work with GAP.

Additionally, the GAP kernel needs a flat address space, that is all the memory is available in one contiguous chunk.

Note that this implies that there is no point in trying to port GAP to plain MS-DOS running on IBM PCs and compatibles. The version of GAP for IBM PC compatibles that we provide runs on machines with the Intel 80486, Pentium or beyond processor under 32-bit Windows. (This is also necessary, because, as just mentioned, GAP wants to view its memory as a large flat address space.)

Next let us turn to the requirements for the C compiler and its library.

As was already mentioned, the GAP kernel is written in the C language. We have tried to use as few features of the C language as possible. GAP has been compiled without problems with compilers that adhere to the old definition from Kernighan and Ritchie, and with compilers that adhere to the new definition from the ANSI-C standard.

Porting GAP to another UNIX should not be hard. You need some very basic understanding of C and UNIX. If you plan to port GAP to a non-UNIX system please contact support@gap-system.org.

The configuration script runs various tests to determine the configuration of your system. It produces a file `bin/`architecture`/config.h` which contains definitions according to the test results. It might be, however, that the tests used don't produce on your machine the results they are expected to or that further tests are necessary. If this is the case the easiest way is to edit the `config.h` script, remove all object files and call `make` in the `bin/`architecture`` subdirectory. If you have to resort to changing or amending this file, please tell us what had to be changed (mail to support@gap-system.org). If you had to add further definitions please also tell what properties of your system these `define`s represent.

If GAP compiles but crashes while reading the library or during a garbage collection with a bus error it is possible that the configuration script did not guess the permitted pointer alignment correctly. This value is stored in the line

    #define C_STACK_ALIGN      2

of `config.h`. Increase the value to the next power of 2 ( ≤ 8) and compile GAP anew.

There is still a `Makefile` in the `src` directory, but it is not used by the configuration process any longer. As a last resort you might want to try this file, but please still report your problems to `support`.

## 73.14 GAP for Macintosh OS X

OS X, the new version of the Macintosh operating system, is built on top of a variant of Unix. Thus there are two ways to run GAP under this operating system.

The first way is simply to follow the instructions in section GAP for MacOS below and to run the binary we provide in the ``Classic'' environment.

The second way is to install the Unix version of GAP.

We recommend to use this (Unix) version because you will be able to use all features of GAP as well as all packages. However for installation you might need a basic knowledge of Unix. Note also that the Unix version of GAP uses Unix style text files. (These files differ from older style macintosh text files in that lines do not contain a trailing `CR` character. Depending on what text editor you use you might not be able to inspect GAP library files and potentially might run into problems with program files you create if they contain strings that go over several lines.)

The following are a couple of notes and remarks about this:

You will need a compiler. The `gcc` C compiler is not installed by default, but is part of the ``Developer tools'' package. This package might be in an installer package already on your system (look at the `Installer` folder under `Applications`), if not you can get it for free from Apple by registering as a developer. See http://developer.apple.com for details. For the ``Panther'' release (10.3) of OS X, `gcc` is part of the ``XCode'' development tools which you should install.

To compile and run GAP you will have to open the `Terminal` application and type the Unix command into its window. The `Terminal` application can be found in the `Utilities` folder in the `Applications` folder. GAP also will run in such a window.

The next thing to note is that you should get the Unix type GAP archives, i.e. usually the tar archive, not the zip archive (You won't be able to compile the program as given in the `.zip` archive).

(If you prefer to use the `.zoo` type archive over `.tar` you can use this as well. However then you will need to use the Unix version of `unzoo`, which you will need to compile first by the command

    gcc -o unzoo -DSYS_IS_UNIX -O unzoo.c

If you use the Macintosh version of the `unzoo` extractor, the text files will be converted to MacOS format and you will have problems with the compilation.)

Go (using the `cd` command in the terminal window) into the directory where you want to install GAP, and copy the archives (and the unzoo program if you want to use `zoo`) in this directory. Then extract the archive by the command

    tar zxvf gap4r4p6.tar.gz

(respectively -- if you prefer `zoo` --

    gcc -o unzoo -DSYS_IS_UNIX -O unzoo.c
    ./unzoo -x gap4r4p6.zoo

)

Then simply follow the Unix installation instructions to compile GAP.

## 73.15 GAP for MacOS

This section contains information about GAP that is specific to the port of GAP for Apple Macintosh systems under MacOS (simply called GAP for MacOS below).

To run GAP for MacOS you need an Apple Macintosh with a Motorola M68020, M68030, or M68040 processor, or a Power Macintosh. The computer must have at least 16MByte of (physical) memory and a harddisk. For serious calculations, much more may be needed. The operating system must be System 7 or higher. GAP for MacOS runs under System X, however only in Classic Mode.

The section Copyrights describes the copyright as it applies to the executable version that we distribute. The section Installation of GAP for MacOS describes how you install GAP for MacOS.

Please refer to the relevant sections of Chapter Running GAP in the GAP reference manual (included with the GAP distribution for an overview over the features of GAP for MacOS.

## 73.16 Installation of GAP for MacOS

Installing GAP under MacOS is fairly easy. First, decide into which folder you want to install GAP 4.4.6. GAP will be installed in a subfolder `gap4r4` of this folder. You can later move GAP to a different location.

Note that certain parts of the output in the examples should only be taken as rough outline, especially file sizes and file dates are not to be taken literally.

If you encounter problems please also see section If Things Go Wrong of this document.

Get the Mac-specific files described in Get the Archives, that is, the distribution `gap4r4p6.zoo` and the binary archive `unzoo4r4-PPC.sit`,

How you can get those files is described in the section Get the Archives. Remember that the distribution consists of binary files and that you must transmit them in binary mode.

If the `sit` files did not extract automatically click on them to extract them. If even this fails use one of the standard decompression utilities, such as `Stuffit Expander`.

After this process you should end up with two applications, `GAP 4 PPC` and `unzoo 4.4 PPC`.

The latter is used to uncompress the `.zoo` archives which contain most of GAP. The `zoo` archives we provide for GAP contain comments which indicate whether files are text or binary files. The `unzoo` we provide uses these comments. If you use another zoo extractor you might lose this information and end up with files that contain text but cannot be opened as text files.

The following installation example assumes that you are installing GAP in the folder `Applications` on a PowerPC Macintosh. (For a 68k Macintosh you should replace all references to `PPC` to ones referring to `68K`

Move the file `gap4r4p6.zoo` into the folder `Applications` and drag it onto the icon of `unzoo 4.4 PPC`. You will get many lines of output in this window.

This should have created a folder `gap4r4` in the current folder.

(You will not need the file `gap4r4p6.zoo` any longer. If you are short of disk space you can remove it now.)

If you got not the full distribution file but several small files, extract all of them (except the GAP packages!) in this way.

Move `GAP 4 PPC` and the bugfix file (if there is one) in the folder `gap4r4`. Drag the bugfix file onto the icon of `unzoo 4.4 PPC` to decompress it.

If you got any GAP packages, move them into the `pkg` folder in the folder folder `gap4r4` extract them there, in the same way as the bugfix.

After extraction you may discard all `.zoo` files if you are short of disk space.

The folders `trans`, `small` and `prim` contain data libraries. If you are short of disk space you can erase some of them and any GAP package directories in the `pkg` directory that you don't need, but then of course you will not be able to access these data and packages. (Any GAP package that has a C code component is essentially UNIX-dependent and you may as well delete those; such packages typically describe in their `README` files that they require `configure` and `make` to complete their installation or have a `src` directory.)

Before you use GAP, you should set up GAP's memory allocation, by setting appropriate values by selecting the GAP application and `Get Info...` in the Finder's `File` menu (in order to be able to modify the values there, you have to do this before you launch GAP).

The maximum amount of workspace GAP can use depends on the amount of memory the Finder allocates to GAP when it is launched. The maximum amount of GAP workspace is this value, minus a certain amount used internally by the GAP application (for the PPC version, currently around 1.7 Megabytes, plus the size of the GAP application if you do not use virtual memory, and 2.9 Megabytes for the 68K version), minus any additional amount set with the `-a`, `-P` or `-W` command line options (see below).

You can find information about the amount of free GAP workspace, the total amount of available workspace, and the remaining free memory, by choosing `About GAP` in the `Apple` menu.

To ensure efficient operation, you should not allocate more memory to GAP than the amount of physical memory in your computer. If you are not using virtual memory, the amount may have to be considerably less (depending on your system and the number of other applications which you may want to run at the same time).

If you notice heavy disk use during garbage collections, this is a clear indication that you have allocated too much memory to GAP.

In order to test your installation now run the `GAP` application by clicking on `GAP 4 PPC`. You should get the GAP banner and then the GAP prompt in a window titled `GAP log`. (The process of starting GAP may take a while.)

Try a few things to see if the installation succeeded.

    gap> 2 * 3 + 4;
    10
    gap> Factorial( 30 );
    265252859812191058636308480000000
    gap> Factors( 10^42 + 1 );
    [ 29, 101, 281, 9901, 226549, 121499449, 4458192223320340849 ]
    gap> m11 := Group((1,2,3,4,5,6,7,8,9,10,11),(3,7,11,8)(4,10,5,6));;
    gap> Size( m11 );
    7920
    gap> Length( ConjugacyClasses( m11 ) );
    10

A set of test files is provided, running them all probably takes some 40 minutes on a 200 MHz PPC machine. This is not a necessary part of the installation; it only serves as a confirmation that everything went OK. The full test suite takes some time and uses quite a bit of memory (around 70MB), so you may wish to skip this step or run only part of the tests. This does no harm.

Initially we must ensure that the print width of GAP is 80 characters per line which we achieve with the `SizeScreen` command (otherwise we will be swamped with error messages).

    gap> SizeScreen([80,]);;
    gap> Filename( DirectoriesLibrary("tst"), "testall.g" );
    "./tst/testall.g"
    gap> Read(last);
    [many output lines omitted]

The information about the manual is system independent; you can find it in section The Documentation.

A few final reminders:

- We would appreciate after installation your sending us a short note at support@gap-system.org (even if you have installed GAP 3 before). Generally, we do not reply to such emails; we only use them to gain some idea of how many people use GAP and of the machines/operating systems on which GAP has been successfully installed.

- We also suggest that you subscribe to our `GAP Forum` mailing list; see the GAP web pages for details. Whenever there is a bug fix or new release of GAP this is where it is announced. The `GAP Forum` also deals with user questions of a general nature; bug reports and other problems you have while installing and/or using GAP should be sent to support@gap-system.org.

That's all, your installation should be complete. Please refer to Chapter Running GAP in the GAP reference manual for a description of some special features and options of GAP for MacOS.

We hope that you will enjoy using GAP. Remember, if you have problems, do not hesitate to contact us at support@gap-system.org. See Section If Things Go Wrong for what to include in a bug report.

## 73.17 Expert Windows installation

This section decribes how to get a better shell for GAP and how to install GAP in another directory. These tasks are slightly complicated due to problems in the design of Windows, if you have not edited a batch file before you might want to contact your system administrator for help.

Some users report that the `rxvt` shell (see http://www.rxvt.org) gives a better windows environment for cut/paste etc.

You can find a copy of this program in the `bin` subdirectory of the GAP installation. Please note that this program is not part of the GAP distribution and that we cannot offer any support for it. You can start GAP under this program via the `gaprxvt.bat` script in the `bin` subdirectory.

(The program has been tested only under a particular version of Windows98. It might not work under other releases. It also might be necessary to adapt paths in the batch file.) Under `rxvt` the standard Unix XWindows cut-and-paste operations (left mouse button cuts, middle mouse button pastes) work. After you terminate GAP a text window might stay on which you can safely delete.

If you decide to install GAP in another directory than `C:` you can do so, but you will have to edit a batch file and use this file to start GAP.

First unpack the GAP distribution in the directory you want.

Lets suppose you want GAP to reside in the directory

    C:\MY PROGRAMS\GAP

Extract GAP (as described in the previous section for `C:`) in this directory. (alternatively, you can also first unpack it in

    C:\GAP4R4

test it there first, and afterwards move it in the desired location.)

You now will have to edit the provided batch file, that will be used to start GAP. This batch file is needed, since GAP otherwise will not find its library directories. The file sits in the `bin` directory of the GAP distribution, i.e. in our example

    C:\MY PROGRAMS\GAP\GAPGAP4R4\bin\gap.bat

This file should contain the following single line (which might be broken over in several lines in this manual as the page width is limited):

    "C:\MY PROGRAMS\GAP\GAPGAP4R4\bin\gapw95.exe" -m 14m
      -l "C:\MY PROGRAMS\GAP\GAPGAP4R4" %1 %2 %3 %4 %5 %6 %7 %8

You now should be able to start GAP by clicking this `gap.bat` file.

If you also want to use `rxvt` you have to edit the `gaprxvt.bat` file to take care of the changed path in two places for the GAP binary as well as for the GAP library.

By default, the ``cygwin'' environment we use limits a programs workspace to 128MB of memory. To increase this limit, it is necessary to edit the Windows registry.

WARNING: Editing the registry is the Windows equivalent of open heart surgery. Do not attempt this change if you have no previous experience in doing this. The web page http://www.cygwin.com/cygwin-ug-net/setup-maxmem.html gives further details.

Before changing the entries, you might have to run GAP once first to create the appropriate registry keys.

The shell script `usemem.bat` in the `bin` directory sets a registry entry

    /HKEY_LOCAL_MACHINE/Software/Cygnus Solutions/Cygwin/heap_chunk_in_mb

to decimal 1024.

If you prefer to do the change by hand, open `regedit` and go to the `Cygwin` Key listed above. Then choose `new value` and add `heap_chunk_in_mb`. `Modify` it to contain decimal 1024.

## 73.18 Copyrights

In addition to the general copyright for GAP set forth in the Copyright the following terms apply to the versions of GAP for Windows and MacOS.

The executable of GAP for Windows that we distribute was compiled with the `gnuwin32` compiler of the `cygwin` package. This compiler can be obtained by anonymous `ftp` from a variety of general public FTP archives. Many thanks to the Free Software Foundation and RedHat Software for this amazing piece of work.

The GNU C compiler is

Copyright (C) 2002 Free Software Foundation, Inc. 675 Mass Ave, Cambridge, MA 02139, USA

under the terms of the GNU General Public License (GPL).

The Cygwin32 API library is also covered by the GNU GPL. The executable we provide is linked against this library (and in the process includes GPL'd Cygwin32 glue code). This means that the executable falls under the GPL too, which it does anyhow.

The `cygwin1.dll`, `libW11.dll`, `rxvt.exe` and `regtool.exe` binaries are taken unmodified from the Cygwin distribution. They are copyright by RedHat Software and released under the GPL. You can find more information about `cygwin` under http://www.cygwin.com. You also will be able to obtain the sources for `cygwin` from this place.

The system dependent part of GAP for MacOS was written by Burkhard Höfling (his email address is b.hoefling@tu-bs.de). He assigns the copyright to the GAP group. Many thanks to Burkhard for his help! Burkhard Höfling's port was partly based on an earlier port of GAP for the Mac, which was done by Dave Bayer (dab@math.columbia.edu) and used the Mac Programmers Workshop (MPW) compiler. Many thanks to Dave for his work. Moreover, the built-in editor is based upon the freeware text editor `PlainText` by Mel Park which, in turn, uses `TE32K`, a `TextEdit` replacement by Roy Wood. It also uses `Internet Config`.

For technical reasons we do not distribute the Macintosh specific source and project files as part of the standard archives. If you are interested in compiling GAP yourself, we are happy to provide you with the appropriate files (contact us at support@gap-system.org). The source can be compiled with CodeWarrior Pro 5 with Apple's Universal Headers 3.3 installed.

Please contact the author b.hoefling@tu-bs.de or support@gap-system.org if you need further information.

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GAP 4 manual
August 2005