# acosh(3) [v7 man page]

ACOSH(3) Linux Programmer's Manual ACOSH(3)NAME

acosh, acoshf, acoshl - inverse hyperbolic cosine functionSYNOPSIS

#include <math.h> double acosh(double x); float acoshf(float x); long double acoshl(long double x); Link withFeature Test Macro Requirements for glibc (see feature_test_macros(7)): acosh(): _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 500 || /* Since glibc 2.19: */ _DEFAULT_SOURCE || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE acoshf(), acoshl(): _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || /* Since glibc 2.19: */ _DEFAULT_SOURCE || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE-lm.DESCRIPTION

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 | +-----------------------------+---------------+---------+CONFORMING TO

C99, POSIX.1-2001, POSIX.1-2008. The variant returning double also conforms to SVr4, 4.3BSD.SEE ALSO

asinh(3), atanh(3), cacosh(3), cosh(3), sinh(3), tanh(3)COLOPHON

This page is part of release 4.15 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/. 2017-09-15 ACOSH(3)

## Check Out this Related Man Page

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

atanh, atanhf, atanhl - inverse hyperbolic tangent functionSYNOPSIS

#include <math.h> double atanh(double x); float atanhf(float x); long double atanhl(long double x); Link withFeature 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-lm.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, 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.-1ERRORS

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 thanor greater than +1 errno is set to EDOM. An invalid floating-point exception (FE_INVALID) is raised. Pole error: x is +1 or-1errno is set to ERANGE (but see BUGS). A divide-by-zero floating-point exception (FE_DIVBYZERO) is raised.-1ATTRIBUTES

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.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 4.15 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/. 2017-09-15 ATANH(3)