Hello everybody, Question: what is the output of ex test=1+power(x,4)*sqrt(1+x*x); cout << test.series(x==0,2) << endl; Answer: Order(1) Question: Why? Answer: Because in the x-involving product order=2, degsum=4, ldegree of the sqrt is 0, the sqrt is expanded up to order -2 and Order(x^2)*Order(x^-2)=Order(1). Question: What is to be done now? Answer: Have a look at the attached patch. Bye, Chris Dams