candiate stencils
q1 = v1/3.0 - 7.0/6.0*v2 + 11.0/6.0*v3
q2 =-v2/6.0 + 5.0/6.0*v3 + v4/3.0
q3 = v3/3.0 + 5.0/6.0*v4 - v5/6.0