'Gives the direction ratio between 2 points
Parameters
p : Point3D
Returns
list
Examples
>>> from sympy import Point3D
>>> p1 = Point3D(1, 2, 3)
>>> p1.direction_ratio(Point3D(2, 3, 5))
[1, 1, 2]'

def direction_ratio(self, point):

    return [(point.x - self.x), (point.y - self.y), (point.z - self.z)]
