atanh(3) — Linux manual page


atanh(3)                Library Functions Manual                atanh(3)

NAME         top

       atanh, atanhf, atanhl - inverse hyperbolic tangent function

LIBRARY         top

       Math library (libm, -lm)

SYNOPSIS         top

       #include <math.h>

       double atanh(double x);
       float atanhf(float x);
       long double atanhl(long double x);

   Feature Test Macro Requirements for glibc (see

           _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         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
       │ Interface                           Attribute     Value   │
       │ atanh(), atanhf(), atanhl()         │ Thread safety │ MT-Safe │

STANDARDS         top

       C11, POSIX.1-2008.

HISTORY         top

       C99, POSIX.1-2001.

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

BUGS         top

       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         top

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

Linux man-pages (unreleased)     (date)                         atanh(3)

Pages that refer to this page: acosh(3)asinh(3)catanh(3)cosh(3)sinh(3)tanh(3)