NAME

atanh, atanhf, atanhl — inverse hyperbolic tangent function

LIBRARY

Math Library (libm, -lm)

SYNOPSIS

#include <math.h>

double
atanh(double x);

float
atanhf(float x);

long double
atanhl(long double x);

DESCRIPTION

The atanh(), atanhf(), and atanhl() functions compute the inverse hyperbolic tangent of the real argument x.

RETURN VALUES

If |x|≥1, atanh(x), atanhf(x), and atanhl(x) return +inf, -inf or NaN, and sets the global variable errno to EDOM.

SEE ALSO

acosh(3), asinh(3), exp(3), math(3)

STANDARDS

The atanh() function conforms to ISO/IEC 9899:1999 (“ISO C99”).

HISTORY

The atanh() function appeared in 4.3BSD.