atanh, atanhf, atanhl - inverse hyperbolic tangent function
#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():
_ISOC99_SOURCE ||
_POSIX_C_SOURCE >= 200112L
|| _XOPEN_SOURCE >= 500
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
atanhf(),
atanhl():
_ISOC99_SOURCE ||
_POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
These functions calculate the inverse hyperbolic tangent of
x; that is
the value whose hyperbolic tangent is
x.
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.
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.
For an explanation of the terms used in this section, see
attributes(7).
| Interface |
Attribute |
Value |
| atanh (), atanhf (), atanhl () |
Thread safety |
MT-Safe |
C99, POSIX.1-2001, POSIX.1-2008.
The variant returning
double also conforms to SVr4, 4.3BSD.
In glibc 2.9 and earlier, when a pole error occurs,
errno as set to
EDOM instead of the POSIX-mandated
ERANGE. Since version 2.10,
glibc does the right thing.
acosh(3),
asinh(3),
catanh(3),
cosh(3),
sinh(3),
tanh(3)