# acosh(3) [opendarwin man page]

```ACOSH(3)						   BSD Library Functions Manual 						  ACOSH(3)

NAME
acosh -- inverse hyperbolic cosine function

SYNOPSIS
#include <math.h>

double
acosh(double x);

DESCRIPTION
The acosh() function computes the inverse hyperbolic cosine of the real argument x.

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.

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

STANDARDS
The acosh() function conforms to ISO/IEC 9899:1999(E).

HISTORY
The acosh() function appeared in 4.3BSD.

4.3 Berkeley Distribution					 November 15, 2002					 4.3 Berkeley Distribution```

## Check Out this Related Man Page

```ACOSH(3)						   BSD Library Functions Manual 						  ACOSH(3)

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);