Section (3) acosh
acosh, acoshf, acoshl — inverse hyperbolic cosine function
||long double x
These functions calculate the inverse hyperbolic cosine of
x; that is the value
whose hyperbolic cosine is
On success, these functions return the inverse hyperbolic
x is a NaN, a
NaN is returned.
x is +1, +0 is
x is positive
infinity, positive infinity is returned.
x is less than
1, a domain error occurs, and the functions return a NaN.
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:
xis less than 1
errnois set to EDOM. An invalid floating-point exception (
FE_INVALID) is raised.
For an explanation of the terms used in this section, see attributes(7).
C99, POSIX.1-2001, POSIX.1-2008.
The variant returning double also conforms to SVr4, 4.3BSD.
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Linux libc source code
Lewine_zsingle_quotesz_s _POSIX Programmer_zsingle_quotesz_s Guide_ (O_zsingle_quotesz_Reilly & Associates, 1991)
386BSD man pages
Modified 1993-07-24 by Rik Faith (faithcs.unc.edu)
Modified 2002-07-25 by Walter Harms