osx man page for acosh

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);

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.

4.3 Berkeley Distribution					 December 11, 2006					 4.3 Berkeley Distribution