$\vec{q}$

$\vec{v}$

$\vec{w}$

O: (0, 0, 0)
E = Surface((0, 1, 4) + (r * (-0.5, 1, 0)) + (s * (-0.5, 0, 0.5)), r, -10, 10, s, -10, 10)
D_{(0,0)}: E(0, 0)
D_{(1,0)}: E(1, 0)
D_{(0,1)}: E(0, 1)
D_{(1,1)}: E(1, 1)
D_{(0,-1)}: E(0, -1)
D_{(1,-1)}: E(1, -1)
D_{(-1, 1)}: E(-1, 1)
D_{(-1,0)}: E(-1, 0)
D_{(-1,-1)}: E(-1, -1)
D_{(2,0)}: E(2, 0)
D_{(2,1)}: E(2, 1)
D_{(2,-1)}: E(2, -1)
D_{(0,2)}: E(0, 2)
D_{(-1,2)}: E(-1, 2)
D_{(1,2)}: E(1, 2)
D_{(2,2)}: E(2, 2)
D_{(-2,0)}: E(-2, 0)
D_{(-2,1)}: E(-2, 1)
D_{(-2,2)}: E(-2, 2)
D_{(-2,-1)}: E(-2, -1)
D_{(3,0)}: E(3, 0)
D_{(3,1)}: E(3, 1)
D_{(3,2)}: E(3, 2)
D_{(3,-1)}: E(3, -1)
q = Vector(O, D_{(0,0)})
v = Vector(D_{(0,0)}, D_{(1,0)})
w = Vector(D_{(0,0)}, D_{(0,1)})