The center of Helsinki sports a gorgeous Penrose tiled pavement: Penrose Tiling in Helsinki http://www.suomenkivivalmiste.fi/Ymparistokivet/Helsingin%20keskuskatu%20iso.jpg
Could anybody give me an algorithm that will permit me to find its 'center' - that is, the point around which the five-fold rotational symmetry occurs? I know it may not exist, so ideally the algorithm should tell me if such a center doesn't exist.