Before you can use the linboxing package in GAP, there are several things that you must do. You must install a compatible version of the LinBox library (Section 2.1), and you must build the linboxing package's kernel module (Section 2.2). Finally, you will most likely want to run GAP with special command-line parameters (Section 2.3). This chapter covers all of these technical details.
Before you can install the linboxing package, you need to have built and installed the LinBox library on your machine. At least version 1.1.5 of LinBox is required to use the linboxing package.
LinBox can be downloaded as source code (a .tar.gz
archive) from the LinBox website at http://www.linalg.org/download.html. The linboxing package supports version 1.1.5 of LinBox (released 3 April 2008), and newer versions.
The following sections give a brief summary of how to build and install the LinBox library. Full installation instructions come with the downloaded LinBox source archive, or are available from http://www.linalg.org/linbox-html/install-dist.html.
Before you can build LinBox library you will need the standard tools for building a package from source code (including a C++ compiler such as g++
). The LinBox library itself requires that you already have installed two further libraries:
the GNU Multiprecision Arithmetic (GMP) Library (see http://gmplib.org/)
a library providing the BLAS linear algebra routines (see http://www.netlib.org/blas/)
These libraries may already be installed on your system or be available from your standard package repositories, so you will not usually need to build these from source code (although if you are interested in performance, you should build your own BLAS library, for example using ATLAS http://math-atlas.sourceforge.net/). If you are unsure whether or not you have either the GMP or BLAS libraries installed, the configure
scripts for both LinBox and linboxing check for them in the standard locations and will tell you if they can't find them.
Further details about setting up these prerequisites is available in LinBox's own installation instructions. None of the optional packages that LinBox can also use (such as NTL or Givaro) are required for the linboxing package.
After downloading the LinBox source archive, it can be extracted using
tar -xzf linbox-x.x.x.tar.gz |
which will create a new directory called linbox-x.x.x
(where x.x.x
is the current version number).
Then change to the linbox-x.x.x
directory and type
./configure make sudo make install |
The last command runs make install
with administrator privileges to install the LinBox library in the default location, /usr/local/
.
If the GMP and BLAS libraries (see Section 2.1-2) are not in standard locations, or you do not wish to install LinBox in /usr/local/
(or you cannot), then please refer to the LinBox installation instructions (http://www.linalg.org/linbox-html/install-dist.html) for the necessary configure
options.
To install the linboxing package, you should first unpack the linboxing archive file in a directory in the pkg
hierarchy of your version of GAP. For example, for a package with the extension .tar.gz
, type
tar -xzf linboxing-0.5.1.tar.gz |
This will extract all of the files into a directory called linboxing-0.5.1
.
All of the useful functionality of the linboxing package is provided through a compiled GAP kernel module that uses the LinBox library directly. Change to the linboxing-0.5.1
directory and build the kernel module using the commands
cd linboxing-0.5.1 ./configure make |
The configure
script runs lots of checks and will search for the locations of all of the required other packages, such as GMP, BLAS, LinBox and GAP itself. If there are any problems, it should report them, and if not then make
should proceed with no errors. Note that make install
is not required for linboxing: make
does all that is needed.
If the required packages are not in the standard locations, you can tell configure
where they are using the following command-line switches:
--with-blas=<lib>
specify the name of the BLAS library, or the linker flags needed to use it
--with-gmpprefix=<prefix>
specify the prefix to which GMP library is installed
--with-linboxprefix=<prefix>
specify the prefix to which the LinBox library is installed
--with-gaproot=<path>
specify the path to GAP's root directory
For example, you may need to use these switches in the following common case. If you do not have root access, you may have installed the LinBox library in your home directory at /home/pas/software/
. To do this, you will have configured the LinBox build process using --prefix=/home/pas/software
and when you did make install
, it would have copied the LinBox library and header files into /home/pas/software/include
and /home/pas/software/lib
respectively. You now wish to build this linboxing package. To tell it where to find the LinBox library, you run configure
with the same prefix that you gave to LinBox, i.e. --with-linboxprefix=/home/pas/software
.
GAP and the LinBox library use different methods for allocating memory, and these do not work well together. GAP needs all of its memory to be contiguous, and so needs to have free space at the end of its current allocation if it ever wants to expand its workspace. The LinBox library allocates its memory using malloc
, and allocates memory wherever it feels like it. Because of this, if you run GAP and use the linboxing package, then there is a good chance that when GAP needs more memory it will find that some LinBox-allocated memory gets in the way of it expanding the workspace. In this case, GAP will simply exit (without warning!) with the error cannot extend the workspace any more
.
There are two current solutions to this problem, both of which require GAP to be run with a command-line switch:
malloc
memory for LinBox to useThe -a
command-line option Reference: Advanced Features of GAP tells GAP to pre-allocate some memory that LinBox should, on most systems, use in preference to getting in the way of the GAP workspace. If you set this sufficiently large (i.1. larger than the largest amount of LinBox memory than you are likely to need at one time), then GAP should be able to expand its workspace as much as it likes. For example, to allocate 50Mb of memory to LinBox (enough for 100,000 small integer matrix elements), use
gap -a 50M |
The -m
command-line option Reference: Command Line Options tells GAP to allocate a set number of bytes for the GAP workspace when it starts up. If you set this sufficiently large then GAP will never need to expand its workspace and LinBox can allocate its matrices wherever it likes in the remaining memory. For example, to allocate 256Mb of memory to GAP, use
gap -m 256M |
If you are unsure as to how much memory you might need, refer to Reference: Global Memory Information for various GAP commands to let you see how much memory your GAP workspace is using. Running GAP with the -g
(or -g -g
) command-line switch Reference: Command Line Options can also help you keep track of memory usage.
You can use both of these solutions at the same time, which may be a safe `belt and braces' approach. If you intend to regularly use the linboxing package, you can add these options to the gap.sh
shell script, if you are using it. Future versions of GAP may modify GASMAN storage manager to allow the happy co-existance of GAP memory with malloc
, which would mean that these switches may eventually not be needed.
The linboxing package is not loaded by default when GAP is started. To load the package, type the following at the GAP prompt:
gap> LoadPackage( "linboxing"); |
If linboxing isn't already in memory then it is loaded and the author information is displayed. If you are a frequent user of the linboxing package, you might consider putting this line in your .gaprc
file.
You can test the installation of the linboxing package by running the GAP command TestLinboxing
(3.2-3):
gap> TestLinboxing(); |
This documentation is written using the GAPDoc package, and should be available in PDF, HTML and text formats. It should not normally be necessary to rebuild the documentation (if you are reading this!). However, rebuilding the documentation can be done from within GAP when running on a standard UNIX installation by using the GAP command MakeLinboxingDoc
(3.2-2).
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