double complex catanh(double complex z);
float complex catanhf(float complex z);
long double complex catanhl(long double complex z);
次の関係が成立する:
    catanh(z) = 0.5 * (clog(1 + z) - clog(1 - z))
 
| インターフェース | 属性 | 値 | 
| catanh(), catanhf(), catanhl() | Thread safety | MT-Safe | 
#include <complex.h> #include <stdlib.h> #include <unistd.h> #include <stdio.h>
int
main(int argc, char *argv[])
{
    double complex z, c, f;
    if (argc != 3) {
        fprintf(stderr, "Usage: %s <real> <imag>\n", argv[0]);
        exit(EXIT_FAILURE);
    }
    z = atof(argv[1]) + atof(argv[2]) * I;
    c = catanh(z);
    printf("catanh() = %6.3f %6.3f*i\n", creal(c), cimag(c));
    f = 0.5 * (clog(1 + z) - clog(1 - z));
    printf("formula  = %6.3f %6.3f*i\n", creal(f2), cimag(f2));