NAME

acosh — inverse hyperbolic cosine function

SYNOPSIS

#include <math.h>

double
acosh(double x);

long double
acoshl(long double x);

float
acoshf(float x);

DESCRIPTION

The acosh() function computes the principle value of the inverse hyperbolic cosine of x. The result is in the range [0, +infinity].

SPECIAL VALUES

acosh(1) returns +0.

acosh(x) returns a NAN and raises the "invalid" floating-point exception for x < 1.

acosh(+infinity) returns +infinity.

VECTOR OPERATIONS

If you need to apply the acosh() function to SIMD vectors or arrays, using the following functions provided by the Accelerate.framework may give significantly better performance:

#include <Accelerate/Accelerate.h>

vFloat vacoshf(vFloat x);
void vvacoshf(float *y, const float *x, const int *n);
void vvacosh(double *y, const double *x, const int *n);

SEE ALSO

asinh(3), atanh(3), exp(3), math(3)

STANDARDS

The acosh() function conforms to ISO/IEC 9899:2011.

HISTORY

The acosh() and acoshf() function appeared in 4.3BSD.