Gap interface to Cdd package

Version 2022.11.01
Released 2022-11-01

This project is maintained by Kamal Saleh

Build Status Code Coverage

The GAP 4 package `CddInterface’

Why CddInterface

Every convex polyhedron P has two representations, one as the intersection of finite halfspaces and the other as Minkowski sum of the convex hull of finite points and the nonnegative hull of finite directions. These are called H-representation and V-representation, respectively.

CddInterface is a gap interface with the C package Cddlib which among other things can translate between H,V- representations of a polyhedron P and solve linear programming problems over P, i.e. a problem of maximizing and minimizing a linear function over P. A list of all available operations can be found in the manual.pdf.


To use CddInterace, it has to be compiled. That means you need at the very least a C compiler on your system. If you managed to install GAP, you probably already have one, so we won’t cover this here. However, various other prerequisites are needed, described below.

… when building from a git clone

If you are building CddInterface directly from git, you first need to generate the configure script. This require autoconf. On Debian and Ubuntu, you can install it via

sudo apt-get install autoconf

On macOS, if you are using Homebrew, you can install it via

brew install autoconf

Then run


Now proceed as in the next section

… when building a release version

Compiling CddInterface requires development headers for the GMP library as well as for cddlib. On Debian or Ubuntu, you can install these via

sudo apt-get install libgmp-dev libcdd-dev

On macOS, if you are using Homebrew, you can install them via

brew install gmp cddlib

Most other package managers include comparable packages, at least for GMP. For cddlib, if your package manager does not provide it, we describe further down how to install it yourself.


Assuming the prerequisites are present (see the previous section), you can now build cddlib as follows:

./configure --with-gaproot=path/to/gaproot

where the path/to/gaproot is the path to the folder where you installed and compiled GAP and which contains the file The default value is ../...

Simple installation (includes building the current cdd from source):

For a simplified installation, try the following command in the main CddInterface directory

./ path/to/gaproot

If that does not work, try the following:

Advanced installation (includes building the current cdd from source):

Go inside the CddInterface directory and download some release of cddlib and extract it. For example the release 0.94m:

tar xvf cddlib-0.94m.tar.gz
ln -sf $(pwd)/cddlib-0.94m $(pwd)/current_cddlib

After that, compile cddlib via

cd current_cddlib
mkdir build
./configure --prefix=$(pwd)/build
make install

Cdd should now be installed in the build directory. After that, go back to the CddInterface main folder and install CddInterface with the following commands

./configure --with-gaproot=path/to/gaproot --with-cddlib=$(pwd)/current_cddlib/build

After that, you should be able to load CddInterface.


To create the documentation:

gap makedoc.g

To run the test files

gap tst/testall.g


The package can be updated using the following commands

git pull

Using the package via Docker

With docker app you can run an image of the newest version of gap && CddInterface via the command

docker run -it kamalsaleh/gap_packages

Using the package via Binder

If you want to experiment online with the package you can use notebook.ipynb vie the binder link below.


Of course you are welcome to e-mail me if there are any questions, remarks, suggestions ;)

Kamal Saleh e-mail:


CddInterface is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.