Dear All, I am sending three patches for consideration. First two add some details to the GiNaC tutorial. The third one replaces remove_dirac_ONE() from the clifford.cpp. Currently remove_dirac_ONE() uses exceptions in normal operation to terminate a chain of recurrent calls. Some people would say that exceptions are evil, but this did not cause problems until I try to make a port for another evil---Windows. The exceptions in remove_dirac_ONE() terminated a Qt Windows application although the same code smoothly run under Linux. Thus I re-write remove_dirac_ONE() without exceptions. The signature of the method has to change, but a user may not notice this in the first approximation. Some respective alterations to the tutorial and the check suit are made as well. Best wishes, Vladimir -- Vladimir V. Kisil http://www.maths.leeds.ac.uk/~kisilv/ Book: Geometry of Mobius Transformations http://goo.gl/EaG2Vu Software: Geometry of cycles http://moebinv.sourceforge.net/