The implementation of the micromagnetics package is based on the freely available open source toolbox ``PETSc'' - the Portable, Extensible Toolkit for Scientific Computation [58]. It provides the data structures and low level linear algebra and many utility routines for small serial programs as well as large-scale applications for massively parallel supercomputers. Most important, it has a very clear design and simple interfaces for a steep learning curve and many additional features, which speed up the development process and help identifying and avoiding the pitfalls of parallel programs.