ATANH

Section: Linux Programmer's Manual (3)
Updated: 2002-07-27
Index Return to Main Contents

NAME

atanh, atanhf, atanhl - inverse hyperbolic tangent function

SYNOPSIS

#include <math.h>

double atanh(double x);


float atanhf(float x);


long double atanhl(long double x);

Link with -lm.

DESCRIPTION

The atanh() function calculates the inverse hyperbolic tangent of x; that is the value whose hyperbolic tangent is x. If the absolute value of x is greater than 1.0, acosh() returns not-a-number (NaN) and errno is set.

ERRORS

EDOM: x is out of range.

CONFORMING TO

SVID 3, POSIX, BSD 4.3, ISO 9899. The float and long double variants are C99 requirements.