ATANH(3) Linux Programmer s Manual ATANH(3)
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.
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
atanh(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 || _ISOC99_SOURCE; or cc -std=c99 atanhf(), atanhl(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE; or cc -std=c99
DESCRIPTION The atanh() function calculates the inverse hyperbolic tangent of x; that is the value whose hyperbolic tangent is x.
RETURN VALUE On success, these functions return the inverse hyperbolic tangent of x.
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 mathemati- cally 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. A divide-by-zero floating-point excep- tion (FE_DIVBYZERO) is raised.
CONFORMING TO C99, POSIX.1-2001. The variant returning double also conforms to SVr4, 4.3BSD, C89.
SEE ALSO acosh(3), asinh(3), catanh(3), cosh(3), sinh(3), tanh(3)
COLOPHON This page is part of release 3.22 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.