acos

acos - Arc cosine

float acos ( float $x )

Returns the arc cosine of x in radians. acos() is the complementary function of cos(), which means that a==cos(acos(a)) for every value of a that is within acos()'s range.

Parameters:

x - The number to process. It can be a scalar or an array.

Return Values:

The arc cosine of x in radians. If x is an array, the return value will also be an array.

Version

1.0 and above.