Hello, Can someone tell me how to extract the argument of a function like this (assuming theta is real): u:=exp(I*theta); I tried argument(u); with no success I also tried to capture the parameter passed to the exp function like this: subsindets(u,'specfunc(anything,exp)', f->subsop(0=exparg,f)); exparg is a simple function that returns the imaginary part of its argument. It works well but fails for variables like this: v:=I*exp(I*theta); I would expect the answer to be theta+Pi/2 but my function return theta only!