HP MLIB User's Guide Vol. 2 7th Ed.

Chapter 12 VMATH 811
The arc hyperbolic cosine of the elements of a vector vsAcosh, vdAcosh
Name vsAcosh, vdAcosh
The arc hyperbolic cosine of the elements of a vector
Purpose vsAcosh and vdAcosh calculate the arc hyperbolic cosine function of vector
elements:
y[i] = acosh(a[i]), for 0 <= i <= n-1
Usage VMATH:
#include <vmath.h>
void vsAcosh (int n, const float a[ ], float y [ ] ) ;
void vdAcosh (int n, const double a [ ], double y [ ] ) ;
VMATH8:
#include <vmath8.h>
void vsAcosh (long long n, const float a[ ], float y [ ] ) ;
void vdAcosh (long long n, const double a [ ], double y [ ] ) ;
Input n Number of elements to be calculated.
a Array of length at least n, specifying the input vector.
Output y Array of length at least n, specifying the output vector.