#include <stdio.h> 
#include </usr/include/gsl/gsl_complex.h>
#include </usr/include/gsl/gsl_complex_math.h>

main()
{
gsl_complex z,r, sum;
double x,y;
x= 3;
y= 4;
z = gsl_complex_rect (x,y);
r = gsl_complex_rect (y,x);
sum = gsl_complex_add (z,r);
printf ("The sum is: %f\n", sum);
}