Saiki's algorithm

This [paper](https://npg.copernicus.org/articles/14/615/2007/) introduces an algorithm for PO detection for continuous-time systems. WIP code for this algorithm can be seen [here](https://gist.github.com/JonasKoziorek/6fd726120df730ac4aadac0cbbde7148). It is unclear to me whether the algorithm is even worth implementing.