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CATANH(3)                 (2020-06-09)                  CATANH(3)

NAME
catanh, catanhf, catanhl - complex arc tangents hyperbolic

SYNOPSIS
#include <complex.h>

double complex catanh(double complex z);
float complex catanhf(float complex z);
long double complex catanhl(long double complex z);

DESCRIPTION
These functions calculate the complex arc hyperbolic tangent
of z. If y = catanh(z), then z = ctanh(y).  The imaginary
part of y is chosen in the interval [-pi/2,pi/2].

One has:

catanh(z) = 0.5 * (clog(1 + z) - clog(1 - z))

VERSIONS
These functions first appeared in glibc in version 2.1.

ATTRIBUTES
For an explanation of the terms used in this section, see
attributes(7).  allbox; lbw30 lb lb l l l.
Interface Attribute Value T{ catanh(), catanhf(), catanhl()

CONFORMING TO
C99, POSIX.1-2001, POSIX.1-2008.

EXAMPLES

#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);
exit(EXIT_FAILURE);
}

Page 1                       Plan 9             (printed 5/18/22)

CATANH(3)                 (2020-06-09)                  CATANH(3)

z = atof(argv) + atof(argv) * 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));

exit(EXIT_SUCCESS);
}