cacosh(3)

#include <complex.h>

double complex cacosh(double complex \nz\n);\n
\nfloat complex cacoshf(float complex \nz\n);\n
\nlong double complex cacoshl(long double complex \nz\n);

\n
    cacosh(z) = 2 * clog(csqrt((z + 1) / 2) + csqrt((z - 1) / 2))

/* Link with "-lm" */
#include <complex.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
int
main(int argc, char *argv[])
{
\n
    double complex z, c, f;
\n
    if (argc != 3) {
\n
        fprintf(stderr, "Usage: %s <real> <imag>\n", argv[0]);
\n
        exit(EXIT_FAILURE);
\n
    }
\n
    z = atof(argv[1]) + atof(argv[2]) * I;
\n
    c = cacosh(z);
\n
    printf("cacosh() = %6.3f %6.3f*i\n", creal(c), cimag(c));
\n
    f = 2 * clog(csqrt((z + 1)/2) + csqrt((z - 1)/2));
\n
    printf("formula  = %6.3f %6.3f*i\n", creal(f), cimag(f));
\n
    exit(EXIT_SUCCESS);
}