## Linux and UNIX Man Pages

Test Your Knowledge in Computers #168
Difficulty: Easy
The OSI networking model uses 6 layers and the TCP/IP protocol suite uses a 4 layer model.
True or False?

# acoshl(3) [freebsd man page]

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

NAME
acosh, acoshf, acoshl -- inverse hyperbolic cosine functions

LIBRARY
Math Library (libm, -lm)

SYNOPSIS
#include <math.h>

double
acosh(double x);

float
acoshf(float x);

long double
acoshl(long double x);

DESCRIPTION
The acosh(), acoshf(), and acoshl() functions compute the inverse hyperbolic cosine of the real argument x.  For a discussion of error due to
roundoff, see math(3).

RETURN VALUES
These functions return the inverse hyperbolic cosine of x.  If the argument is less than 1, acosh() raises an invalid exception and returns
an NaN.

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

HISTORY
The acosh(), acoshf(), and acoshl() functions appeared in 4.3BSD, FreeBSD 2.0, and FreeBSD 10.0, respectively.

BSD								   June 9, 2013 							       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);

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.

4.3 Berkeley Distribution					 December 11, 2006					 4.3 Berkeley Distribution```

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