|ACOSH(3P)||POSIX Programmer's Manual||ACOSH(3P)|
double acosh(double x); float acoshf(float x); long double acoshl(long double x);
These functions shall compute the inverse hyperbolic cosine of their argument x.
An application wishing to check for error situations should set errno to zero and call feclearexcept(FE_ALL_EXCEPT) before calling these functions. On return, if errno is non-zero or fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has occurred.
For finite values of x < 1, a domain error shall occur, and either a NaN (if supported), or an implementation-defined value shall be returned.
If x is NaN, a NaN shall be returned.
If x is +1, +0 shall be returned.
If x is +Inf, +Inf shall be returned.
If x is -Inf, a domain error shall occur, and a NaN shall be returned.
- Domain Error
- The x argument is finite and less than +1.0, or is -Inf.
If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then errno shall be set to [EDOM]. If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then the invalid floating-point exception shall be raised.
The following sections are informative.
The Base Definitions volume of POSIX.1‐2017, Section 4.20, Treatment of Error Conditions for Mathematical Functions, <math.h>
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|2017||IEEE/The Open Group|