hypot
    (PHP 4 >= 4.1.0, PHP 5)
hypot -- 
     Calculate the length of the hypotenuse of a right-angle triangle
    
Description
float 
hypot ( float x, float y )
     hypot() returns the length of the hypotenuse of a
     right-angle triangle with sides of length x and
     y, or the distance of the point
     (x, y) from the origin.
     This is equivalent to sqrt(x*x + y*y).