NAME

asinh, acosh, atanh − Compute inverse hyperbolic functions

LIBRARY

Math Library (libm.a)

SYNOPSIS

#include <math.h>

double asinh  (double x);
float  asinhf (float  x);
double acosh  (double x);
float  acoshf (float  x);
double atanh  (double x);
float  atanhf (float  x);

STANDARDS

Interfaces documented on this reference page conform to industry standards as follows:

asinh():  XPG4−UNIX

acosh():  XPG4−UNIX

atanh():  XPG4−UNIX

Refer to the standards(5) reference page for more information about industry standards and associated tags. 

DESCRIPTION

The asinh() and asinhf() functions return the hyperbolic arc sine of x, in the range [−infinity, +infinity] where asinh(x) = ln(x + sqrt(x∗∗2 + 1)).  The asinh() function is the reverse function of sinh() where asinh(sinh(x)) = x. 

The acosh()  and acoshf() functions return the hyperbolic arc cosine of x, in the range [1, +infinity] where acosh(x) = ln(x + sqrt(x∗∗2 − 1)).  The acosh() function is the reverse function of cosh() where acosh(cosh(x)) = x. 

The atanh() and atanhf() functions return the hyperbolic arc tangent of x, in the range (−1, 1). The atanh() function is the reverse function of tanh() where atanh(tanh(x)) = x. 

The following table describes function behavior in response to exceptional arguments: