Hi, there appears to be a bug in the multivariate factor() routine. For some expressions it seems to get stuck in an infinite loop, without any result or error messages appearing. The simplest expression I could find to reproduce this behaviour consistently is the expanded form of (3*x+2*y)*(x+y+x*y). For some other expressions (e.g. (x+2*y)*(x+y+x*y)) the problem occurs randomly, but not all the time. I'm guessing this is due to the randomness of the internal ordering of symbols. A minimal example code exhibiting the problem is attached. I've reproduced this bevahiour on openSuse and Ubuntu machines using GiNaC 1.6.2 and CLN 1.3.2. Regards, Thomas