# acosh(3) [netbsd man page]

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

NAME
acosh, acoshf -- inverse hyperbolic cosine function

LIBRARY
Math Library (libm, -lm)

SYNOPSIS
#include <math.h>

double
acosh(double x);

float
acoshf(float x);

DESCRIPTION
The acosh() and acoshf() functions compute the inverse hyperbolic cosine of the real argument x.

RETURN VALUES
If x is less than one, acosh(x) and acoshf(x) return NaN and set the global variable errno to EDOM.

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

HISTORY
The acosh() function appeared in 4.3BSD.

BSD								    May 6, 1991 							       BSD```

## 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);