atan - chung-leong/qb GitHub Wiki
atan - Arc tangent
float atan ( float $x )
Returns the arc tangent of x in radians. atan() is the complementary function of tan(), which means that a==tan(atan(a)) for every value of a that is within atan()'s range.
Parameters:
x - The argument to process. It can be a scalar or an array.
Return Value:
The arc tangent of x in radians. If x is an array, the return value will also be an array.
Version
1.0 and above.