GAP package Wedderga

Central Idempotents and Simple Components of Group Algebras

Authors and maintainers: Ángel del Río, Osnel Broche Cristo, Allen Herman, Alexander Konovalov, Aurora Olivieri, Gabriela Olteanu, Inneke Van Gelder
Needs: GAP, version at least 4.7, GAP package GAPDoc.
Operating systems: UNIX, Windows
Current version: 4.7.2
Contact: alexk at
Download: see below


The title Wedderga stands for "Wedderburn decomposition of group Algebras. This is a GAP package to compute the simple components of the Wedderburn decomposition of semisimple group algebras of finite groups over abelian number fields and over finite fields. It also contains functions that compute the primitive central idempotents of the same kind of group algebras, and to construct crossed products over a group with coefficients in an associative ring with identity and the multiplication determined by a given action and twisting.

The Wedderga package was submitted for consideration to the GAP Council on September 25, 2006. The package became accepted since the version 4.3.3 released on May 29, 2008.


Download and unpack the archive given below in the pkg subdirectory of your GAP installation.

Follow the instructions in the chapter `Installation' of the manual. The manual is available below or in the subdirectory wedderga/doc.

Online Documentation

The manual of the package is available in several formats. If the package has been installed properly, all of these documents are also accessible through the GAP online help.

Wedderga manuals

Package Archive for Download

The Wedderga package is available in the following format:

The PackageInfo.g file is available as plain text file.


We maintain a list of references to the Wedderga package. It contains works where the Wedderga package was cited. We will appreciate your additions or corrections to this list sent to one of the package maintainers.

If you publish a result that was partially obtained with the help of Wedderga, please cite it in the following form:

O. Broche Cristo, A. Herman, A. Konovalov, A. Olivieri, G. Olteanu, Á. del Río and I. Van Gelder.
Wedderga --- Wedderburn Decomposition of Group Algebras, Version 4.7.2; 2013


Wedderga development at various stages was supported by: