Hello, I found out that trying to calculate ex(sqrt(1+x*x)*sqrt(1+2*x*x)).series(x,2) throws an exception. This is because on the one hand the expansion of a multiplication tries to find the ldegree of every factor and on the other hand ldegree of a power throws if the base of the power contains the variable and the exponent is non-integer. A patch is included. Goodbye, Chris Dams