/* comple.c                            */
/* check that exp(i * pi) == -1        */
/* compile with: gcc complex.c -lm     */
#include <math.h>          /* for atan */
#include <stdio.h>
#include <complex.h>

int main(void) {
  double pi = 4 * atan(1.0);
  double complex z = cexp(I * pi);
  printf("exp(i*pi) = %f + %fi\n", creal(z), cimag(z));
}