Hi, there seems to be a bug in the series() implementation. The attached code causes a segfault. As log(-x) doesn't depend on the expansion parameter ep, series() should return log(-x). The bug only occurs, if x is defined as possymbol, so it might have something to do with the branch cut of the logarithm. I reproduced the bug with GiNaC 1.6.2 and the current git version. Regards, Mario