Hi Alexei, Am 21.02.2010 20:44, schrieb Alexei Sheplyakov: > It looks like a bug in gcd routines. Proof: try computing > > gcd(expand(t), expand(diff(t, q))) Another proof: gdb's output ;-) > I'll try to find out what's going on here. thanks! I'll leave the bug to you, then. Regards, Jens