d2wdz2+(1a1a2zα+1b1b2zβ+1c1c2zγ)dwdz+((αβ)(αγ)a1a2zα+(βα)(βγ)b1b2zβ+(γα)(γβ)c1c2zγ)w(zα)(zβ)(zγ)=0,