table of contents
atanh(3) | Library Functions Manual | atanh(3) |
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);
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 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 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 |
atanh (), atanhf (), atanhl () | Thread safety | MT-Safe |
STANDARDS¶
C11, POSIX.1-2008.
HISTORY¶
C99, POSIX.1-2001.
The variant returning double also conforms to SVr4, 4.3BSD.
BUGS¶
In glibc 2.9 and earlier, when a pole error occurs, errno is set to EDOM instead of the POSIX-mandated ERANGE. Since glibc 2.10, glibc does the right thing.
SEE ALSO¶
2024-05-02 | Linux man-pages (unreleased) |