arccos

Definition: atom x2 = arccos(atom x1)
Description: Return an angle with cosine equal to x1.
Comments: The argument, x1, must be in the range -1 to +1 inclusive.

A value between 0 and PI radians will be returned.

This function may be applied to an atom or sq_arccos() to all elements of a sequence. The rules for sequence operations apply.

arccos() is not as fast as arctan().
Example:
s = arccos(-1)
-- s is 3.141592654
See Also: cos, arcsin, arctan