ATANH, ATANHF, ATANHL - reference manual online

Inverse hyperbolic tangent function.

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 || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED || _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L; or cc -std=c99 atanhf(), atanhl(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L; or cc -std=c99
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 │ └─────────────────────────────┴───────────────┴─────────┘
CONFORMING TO C99, POSIX.1-2001, POSIX.1-2008. The variant returning double also conforms to SVr4, 4.3BSD, C89.
BUGS 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 ALSO acosh(3), asinh(3), catanh(3), cosh(3), sinh(3), tanh(3)
COLOPHON This page is part of release 4.04 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at
2015-04-19 ATANH(3)
This manual Reference Other manuals
atanh(3) referred by acosh(3) | asinh(3) | catanh(3) | cosh(3) | sinh(3) | tanh(3)
refer to acosh(3) | asinh(3) | attributes(7) | catanh(3) | cosh(3) | feature_test_macros(7) | math_error(7) | sinh(3) | tanh(3)