#include <stdio.h>
#include <math.h>
#include <complex.h>
int main(void)
{
double complex n = cacos(-2);
printf("cacos(-2+0i) = %f%+fi\n", creal(n), cimag(n));
printf("cacos(-2+0i) = %f + i%f\n", creal(n), cimag(n));
return 0;
}
/*
run:
cacos(-2+0i) = 3.141593-1.316958i
cacos(-2+0i) = 3.141593 + i-1.316958
*/