'Returns the Cartesian/rectangular coordinates of this point
wrt the origin of the given CoordSys3D instance.
Parameters
coordinate_system : CoordSys3D
The coordinate system to express the coordinates of this
Point in.
Examples
>>> from sympy.vector import Point, CoordSys3D
>>> N = CoordSys3D(\'N\')
>>> p1 = N.origin.locate_new(\'p1\', 10 * N.i)
>>> p2 = p1.locate_new(\'p2\', 5 * N.j)
>>> p2.express_coordinates(N)
(10, 5, 0)'

def express_coordinates(self, coordinate_system):

    pos_vect = self.position_wrt(coordinate_system.origin)
    return tuple(pos_vect.to_matrix(coordinate_system))
