Calculate overlap in 2D space

def calc_2d_forces(self,x1,y1,x2,y2,width):
        """Calculate overlap in 2D space"""
        #calculate a
        if x1>x2:
            a = x1-x2
        else:
            a = x2-x1

        a_sq=a*a
        #calculate b
        if y1>y2:
            b = y1-y2
        else:
            b = y2-y1

        b_sq=b*b

        #calculate c
        from math import sqrt
        c_sq = a_sq+b_sq

        c = sqrt(c_sq)

        if c > width:
            return 0,0
        else:
            overlap = width-c
        return -overlap/2, overlap/2