Dear All, I am attaching two patches which were submitted in Nov 2013, and discussed at http://www.ginac.de/pipermail/ginac-devel/2013-November/ The first patch was modified after this discussion and no further objection were raised to either of them. Best wishes, Vladimir -- Vladimir V. Kisil email: kisilv@maths.leeds.ac.uk www: http://www.maths.leeds.ac.uk/~kisilv/ Book: Geometry of Mobius Transformations http://www.worldscientific.com/worldscibooks/10.1142/p835