Name
atanh, atanhf, atanhl - inverse hyperbolic tangent functionLibrary
Math library ( libm ", " -lm )Synopsis
#include <math.h> double atanh(double x );Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
float atanhf(float x );
long double atanhl(long double x );
atanh()
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 500 || /* Since glibc 2.19: */ _DEFAULT_SOURCE || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
atanhf() atanhl()
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || /* Since glibc 2.19: */ _DEFAULT_SOURCE || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
Description
These functions calculate the inverse hyperbolic tangent ofx ;
that is the value whose hyperbolic tangent is x
. Return Value
On success, these functions return the inverse hyperbolic tangent ofx
. If x is a NaN, a NaN is returned.
If x is +0 (-0), +0 (-0) is returned.
If x is +1 or -1, a pole error occurs, and the functions return HUGE_VAL ,HUGE_VALF ,or HUGE_VALL ,respectively, with the mathematically correct sign.
If the absolute value of x is greater than 1, a domain error occurs, and a NaN is returned.
Errors
See math_error(7) for information on how to determine whether an error has occurred when calling these functions.The following errors can occur:
Domain error: x less than -1 or greater than +1 errno is set to EDOM .An invalid floating-point exception ( FE_INVALID ) is raised.
Pole error: x is +1 or -1 errno is set to ERANGE (but see BUGS). A divide-by-zero floating-point exception ( FE_DIVBYZERO ) is raised.
Attributes
For an explanation of the terms used in this section, see attributes(7).Interface | Attribute | Value |
T} | Thread safety | MT-Safe |
Standards
C11, POSIX.1-2008.History
C99, POSIX.1-2001.The variant returning double also conforms to SVr4, 4.3BSD.