DUNE as an Example of Sustainable Open Source Scientific Software Development

DUNE, the “Distributed and Unified Numerics Environment” [5, 2, 1, 3] is a modular software toolbox for solving partial differential equations. When initiating DUNE the rule in scientific software development was that PhD students were given a legacy software and further extended it during their PhD until it did fit their needs. The purpose of this custom software was to produce publishable scientific results. The software itself was only a (unwanted) by-product. As such it was neither designed for maintainability nor well documented. Even institutions that have an inhouse software or framework developed by a group of individual researchers suffer from such development practices. This has produced many rather unmaintainable software dinosaurs. They have a lot of hidden undocumented features unknown to current developers. This leads to new researchers reimplementing functionality that they need. Often the developing institutions have a rather narrow application area for their software. Therefore it is almost impossible to use the software in a slightly different area as originally intended. This again leads to researchers having to reimplement the wheel if they want to switch the application area or even the underlying numerics. This situation was a thorn in the eyes of the DUNE developers. At the time of DUNE’s inaugurating meeting 2002 they decided to attack these problems. The developers come from different institutions and have different (numerical) backgrounds. Quite a few of them had their own legacy inhouse software when DUNE started, at that time mostly grid managers. The purpose was to develop