ATANH(3) Linux Programmer's Manual ATANH(3)NAME
atanh, atanhf, atanhl - inverse hyperbolic tangent function
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)):
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 ||
_XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED || _ISOC99_SOURCE ||
_POSIX_C_SOURCE >= 200112L;
or cc -std=c99
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 ||
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
or cc -std=c99
The atanh() function calculates 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 mathemati‐
cally 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 float‐
ing-point exception (FE_DIVBYZERO) is raised.
C99, POSIX.1-2001. The variant returning double also conforms to SVr4,
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.
SEE ALSOacosh(3), asinh(3), catanh(3), cosh(3), sinh(3), tanh(3)COLOPHON
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