| Domain error: x is less than 1 | errno is set to EDOM. An invalid floating-point exception (FE_INVALID) is raised. |
NAME
acosh, acoshf, acoshl - inverse hyperbolic cosine function
LIBRARY
Math library (libm, -lm)
SYNOPSIS
#include <math.h>double acosh(double \nx\n);\n
\nfloat acoshf(float \nx\n);\n
\nlong double acoshl(long double \nx\n);acosh():
\n
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
\n
|| _XOPEN_SOURCE >= 500
\n
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
\n
|| /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCEacoshf(), acoshl():
\n
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
\n
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
\n
|| /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCEDESCRIPTION
These functions calculate the inverse hyperbolic cosine of x; that is the value whose hyperbolic cosine is x.
RETURN VALUE
On success, these functions return the inverse hyperbolic cosine of x.
If x is a NaN, a NaN is returned.
If x is +1, +0 is returned.
If x is positive infinity, positive infinity is returned.
If x is less than 1, a domain error occurs, and the functions return a NaN.
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 is less than 1
errno is set to EDOM. An invalid floating-point exception (FE_INVALID) is raised.
ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).
| Interface | Attribute | Value |
| acosh (), acoshf (), acoshl () | Thread safety | MT-Safe |
STANDARDS
C11, POSIX.1-2008.
HISTORY
C99, POSIX.1-2001.
The variant returning double also conforms to SVr4, 4.3BSD.
SEE ALSO
asinh(3), atanh(3), cacosh(3), cosh(3), sinh(3), tanh(3)