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# catanh(3)

2019-03-06
Aliases: catanhf(3), catanhf(3), catanhf(3), catanhf(3), catanhf(3), catanhf(3), catanhl(3), catanhl(3), catanhl(3), catanhl(3), catanhl(3), catanhl(3)

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### man-pages

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## 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).
 Interface Attribute Value Thread safety MT-Safe

## CONFORMING TO

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

## EXAMPLE

#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);
}
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); }