atan2
(PHP 4, PHP 5)
atan2 — Arc tangent of two variables
Description
    float atan2
     ( float $y
    , float $x
    )
  This function calculates the arc tangent of the two variables x and y. It is similar to calculating the arc tangent of y / x, except that the signs of both arguments are used to determine the quadrant of the result.
The function returns the result in radians, which is between -PI and PI (inclusive).
Parameters
- y
- 
      Dividend parameter 
- x
- 
      Divisor parameter 
Return Values
The arc tangent of y/x in radians.