ACOSHSection: Linux Programmer's Manual (3)
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NAMEacosh, acoshf, acoshl - inverse hyperbolic cosine function
#include <math.h> double acosh(double x);Link with -lm.
float acoshf(float x);
long double acoshl(long double x);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 || _ISOC99_SOURCE; or
acoshf(), acoshl(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE; or cc -std=c99
DESCRIPTIONThe acosh() function calculates the inverse hyperbolic cosine of x; that is the value whose hyperbolic cosine is x.
RETURN VALUEOn 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.
ERRORSSee 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.
CONFORMING TOC99, POSIX.1-2001. The variant returning double also conforms to SVr4, 4.3BSD, C89.
SEE ALSOasinh(3), atanh(3), cacosh(3), cosh(3), sinh(3), tanh(3)
COLOPHONThis page is part of release 3.21 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.