Trigonometric function that returns the hyperbolic arc-cosine of a number
Implemented by: Gambas
With variations:
Also written as:
Gambas also accepts the function written as Acsh().
The BASIC Cookbook points out that BASICs which don't implement the function can achieve the same results, for a given X argument, with the following formula:
LOG(X + SQR(X*X - 1))