acosh

acosh

Compute the inverse hyperbolic cosine

Portability: C99

SYNOPSIS
DESCRIPTION
RETURN VALUE
DIAGNOSTICS
RELATED FUNCTIONS
SEE ALSO

SYNOPSIS

   #include <math.h>

   double acosh(double x);
   float acoshf(float x);
   long double acoshl(long double x);

DESCRIPTION

acosh computes the inverse hyperbolic cosine of the argument x, expressed by the following relation:

[IMAGE]

x must not be less than 1.0.

The function name acoshf should be used for float arguments, and acoshl for long double arguments. Alternately, if the header file tgmath.h is included, acosh may be used with any numeric argument type.

RETURN VALUE

acosh returns the inverse hyperbolic cosine of the argument x, provided that this value is defined and expressible. The value returned will be positive or zero, except in the case of a domain error.

DIAGNOSTICS

An error message is written to the standard error file (stderr) by the runtime library if x is less than 1.0. In this case, acosh returns 0.0 for HFP, or a NaN for BFP.

RELATED FUNCTIONS

asinh, atanh, _matherb, _matherr

SEE ALSO

"Mathematical Functions" in Chapter 2, "Function Categories"

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