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# Category Archives: GAP

## GAP on GitHub: one year on

*We present a guest blog post by Olexandr Konovalov, in which he mentions a number of **activities that were partially or fully supported by the CoDiMa project. The original version of the post is located at **his homepage.*

This post is based on my earlier comment on the pull request number one submitted to the GAP repository on GutHub a little bit more than a year ago.

Of course, GAP is not new to the version control. The first revision in the CVS repository for GAP 4 is dated July 3rd 1996. Then 16 years later, in summer 2012 the repository had been converted to Mercurial (thanks to Max Horn!) after the release of GAP 4.5. In February 2015 the Mercurial repository had been converted to Git (thanks to Chris Jefferson!), and we started to host it on GitHub at https://github.com/gap-system/gap.

Below there are some highlights of what happened during the first year after that:

- On 26th February 2016 there were In total 640 pull requests and issues in this repository, namely:
- 120 open + 133 closed issues
- 32 open + 356 closed pull requests
- That’s more than one new pull request a day!

- While the ratio for open/closed issues is nearly 50:50, “if things are done, they are done”: pull requests are normally reviewed and getting merged, so the ratio open/closed for pull requests is about 1:10.
- We had several very productive GAP Days in Aachen, Trondheim and St Andrews.
- We have a gap-system virtual organisation on GitHub which also hosts repositories for other development tools, GAP Website, etc.
- We have an expanding virtual organisation for gap-packages.
- There is even more activity with GAP packages, since some of them are openly developed elsewhere (we are trying to keep an up-to-date list at this page).
- There is an active open GAP development mailing list.
- There is also a growing Wiki with documentation for developers.
- In 2015, we made two minor releases based on the stable-4.7 branch of the GitHub repository (4.7.8 and 4.7.9).
- We put a lot of efforts in making GAP more robust and test it better, in particular, we now run nightly check of the code coverage and publish code coverage reports.
- And we have just announced the first major release of GAP 4.8.2, which is the first major release of GAP that has been made from this repository! The overview of changes between GAP 4.7 and GAP 4.8 highlights most significant ones, including support for partially variadic functions, better tools for testing, debugging and profiling, function calls with timeouts, 12 new packages redistributed with GAP, and other changes.

Congratulations and thanks to everyone who worked on making all of this possible!!!

In addition, this visualisation, produced with gource, shows files and directories that were modified in the master branch of the core GAP system during the 1st year on GitHub. The large cluster in the top right corner corresponds to the GAP library. The top left corner is occupied by the GAP kernel. The pink cluster in the bottom represents GAP regression tests, and the main GAP manuals are marked by green. There are already changes waiting for GAP 4.9!

## Nikolaus conference 2015

Just like every year since about 2004 I have attended the Nikolauskonferenz in Aachen in December 2015.

Nikolaus is a relatively small meeting of mathematicians interested in group- or representation theory, and computational methods in these fields in particular. As such this meeting is a good venue to meet users of the GAP system, hear about their experiences and do some advertising work for HPC-GAP.

One particular highlight to be mentioned here was my conversation with Sergio Siccha, who just started his PhD in Aachen and wants to use HPC-GAP, and Jürgen Müller, one of the authors of the Orb GAP package. Sergio is going to attend our first joint GAP and SageMath days in January and we will work on a HPC version of the orbit-by-suborbit algorithm.

I also sat down with Rebecca to discuss our recently funded project.

Thanks to Frank Lübeck, who has been organising this meeting for as long as I can remember, to all the speakers who gave interesting talks, and all attendees who made this meeting a memorable experience.

Last but not least, thanks to CoDiMa for making this visit possible for me!

## GAP 4.7.9 released

*New release of GAP 4.7.9 was announced in the beginning of December 2015. In this guest post (reproduced from here), Olexandr Konovalov tells about his work from research software engineering perspective*.

This week I was mainly wearing my Research Software Engineer (RSE) hat. RSE support for the GAP system has three related strands: development of the core GAP system; support of package authors and other GAP users; training future users and contributors to the system. They are all important for the thriving community of users and developers, and this week I’ve done something to advance each of them.

First, I’ve prepared a new release of GAP 4.7.9. (more…)

## First Joint GAP-SageMath Days

The **First Joint GAP-SageMath Days **will be held at the University of St Andrews on January 18th-22nd, 2016. The focus of this event will be on improving GAP-SageMath integration and interaction between our systems. Further details will be posted soon!

## First CoDiMa Training School in Computational Discrete Mathematics

We have just finalised the date and location for the **First CoDiMa Training School in Computational Discrete Mathematics** which will take place at the University of Manchester on November 16th-20th, 2015. This school is intended for PhD students and researchers from UK institutions. It will start with the 2-days hands-on **Software Carpentry** workshop covering basic concepts and tools, including working with the command line, version control and task automation, continued with introductions to **GAP** and **SageMath** systems, and followed by the series of lectures and exercise classes on a selection of topics in computational discrete mathematics. The school will finish at Friday lunchtime, with an option to stay for the **NBSAN** (North British Semigroups and Applications Network) meeting on Friday afternoon.

## Average order of group elements: a demo of test-driven development in GAP

By Olexandr Konovalov, Research Fellow in the Centre for Interdisciplinary Research in Computational Algebra, University of St Andrews (reproduced from the original post here)

*This blog post is based on an improvised demo that I gave at the Newcastle University on May 21st, 2015 during a short visit supported by the CoDiMa project.*

Let’s consider the following exercise: for a finite group *G*, calculate the average order of its element (that is, the sum of orders of its elements divided by the order of the group). We begin with a very straightforward approach, iterating over all elements of the group in question:

```
gap> S:=SymmetricGroup(10);
Sym( [ 1 .. 10 ] )
gap> sum:=0;
0
gap> for g in S do
> sum := sum + Order(g);
> od;
gap> sum/Size(S);
39020911/3628800
```

Now assume that we would like to save this fragment of the GAP code and later repeat this calculation for some other groups. (more…)