State space transformation. The idea of our method can be described more easily by considering a mechanical example: In order to model the movement of a mass in space one has to choose a certain coordinate system. However, if this coordinate system is not adjusted to the problem (like shown on the left site) the model equations will be more complicate than in a transformed coordinate system.
Conzelmann et al. BMC Bioinformatics 2006 7:34 doi:10.1186/1471-2105-7-34