public static int dot (int v1sx, int v1sy, int v1ex, int v1ey,
                           int v2sx, int v2sy, int v2ex, int v2ey)
    {
        return ((v1ex - v1sx) * (v2ex - v2sx) + (v1ey - v1sy) * (v2ey - v2sy));
    }
public static int dot ( int v1sx , int v1sy , int v1ex , int v1ey , int v2sx , int v2sy , int v2ex , int v2ey ) { return ( ( v1ex - v1sx ) * ( v2ex - v2sx ) + ( v1ey - v1sy ) * ( v2ey - v2sy ) ) ; }
Computes and returns the dot product of the two vectors.  See {@link
#dot(Point,Point,Point,Point)} for an explanation of the arguments