Tribblix: manual page: acosh.3m

ACOSH(3M) Mathematical Library Functions ACOSH(3M)

NAME

acosh, acoshf, acoshl - inverse hyperbolic cosine functions

SYNOPSIS

c99 [ flag... ] file... -lm [ library... ]
#include <math.h>

double acosh(double x);

float acoshf(float x);

long double acoshl(long double x);

DESCRIPTION

These functions compute the inverse hyperbolic cosine of their
argument x.

RETURN VALUES

Upon successful completion, these functions return the inverse
hyperbolic cosine of their argument.

For finite values of x < 1, a domain error occurs and NaN is
returned.

If x is NaN, NaN is returned.

If x is +1, +0 is returned.

If x is +Inf, +Inf is returned.

If x is -Inf, a domain error occurs and NaN is returned.

For exceptional cases, matherr(3M) tabulates the values to be
returned by acosh() as specified by SVID3 and XPG3.

ERRORS

These functions will fail if:

Domain Error
The x argument is finite and less than 1.0, or is
-Inf.

If the integer expression (math_errhandling &
MATH_ERREXCEPT) is non-zero, the invalid floating-
point exception is raised.

The acosh() function sets errno to EDOM if x is less
than 1.0.

USAGE

An application wanting to check for exceptions should call
feclearexcept(FE_ALL_EXCEPT) before calling these functions. On
return, if fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW |
FE_UNDERFLOW) is non-zero, an exception has been raised. An
application should either examine the return value or check the
floating point exception flags to detect exceptions.

An application can also set errno to 0 before calling acosh(). On
return, if errno is non-zero, an error has occurred. The acoshf() and
acoshl() functions do not set errno.

ATTRIBUTES