ATANH(3) | Library Functions Manual | ATANH(3)

# NAME

`atanh`, `atanhf`, `atanhl` — inverse hyperbolic tangent functions

# SYNOPSIS

Math Library (libm, -lm)
`#include <math.h>`

double
`atanh`(double x);

float
`atanhf`(float x);

long double
`atanhl`(long double x);

# DESCRIPTION

The `atanh`() function computes the inverse hyperbolic tangent of the real argument x. The `atanhf`() function is a single precision version of `atanh`(). The `atanhl`() function is an extended precision version of `atanh`().

# RETURN VALUES

If |x|>=1, `atanh`(x), `atanhf`(x) and `atanhl`(x) return +infinity, -infinity or NaN, and set the global variable errno to `EDOM`.

# SEE ALSO

acosh(3), asinh(3), exp(3), fpclassify(3)

# HISTORY

The `atanh`() function appeared in 4.3BSD.

June 7, 2025 | Debian