NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | CONFORMING TO | BUGS | SEE ALSO | COLOPHON

ATANH(3)                  Linux Programmer's Manual                 ATANH(3)

NAME         top

       atanh, atanhf, atanhl - inverse hyperbolic tangent function

SYNOPSIS         top

       #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

DESCRIPTION         top

       These functions calculate the inverse hyperbolic tangent of x; that
       is the value whose hyperbolic tangent is x.

RETURN VALUE         top

       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         top

       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         top

       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         top

       C99, POSIX.1-2001, POSIX.1-2008.

       The variant returning double also conforms to SVr4, 4.3BSD, C89.

BUGS         top

       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         top

       acosh(3), asinh(3), catanh(3), cosh(3), sinh(3), tanh(3)

COLOPHON         top

       This page is part of release 4.08 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
       https://www.kernel.org/doc/man-pages/.

                                 2016-03-15                         ATANH(3)