[GiNaC-list] real and imaginary parts of an expression

[Richard B. Kreckel]

Martin DRUON wrote:
> #include <iostream>
> #include <ginac/ginac.h>
> 
> using namespace GiNaC;
> 
> int main(int argc, char **argv)
> {
>   symbol x("x"), y("y");  // My complex number : x + iy
>   symbol Q("Q"), a("a");  // Parameters
> 
>   // My expression
>   ex f = (Q / 2 * Pi) * log(((x + I * y) - a) / ((x + I * y) + a));
> 
>   std::cout << f << std::endl;
> 
> //  f.real() -> How I can get real part ???
> //  f.imag() -> How I can get imaginary part ???
> 
>   return EXIT_SUCCESS;
> }
> 
> Is it possible easily ?

If write that x+I*y is your complex number, then you're most certainly 
assuming that x and y are real. You should express that by declaring x 
and y as objects of class realsymbol. I guess the same is true for Q and 
a. By default, GiNaC assumes that symbols are complex!

With GiNaC 1.4 you can use ex::real_part() and ex::imag_part(). With 
GiNaC 1.3, you'll have to use ex::conjugate(), as already pointed out by 
Vladimir Kisil.

   -richy.
-- 
Richard B. Kreckel
<http://www.ginac.de/~kreckel/>