\[{\theta_{4}}^{2}\left(0,q\right)\theta_{3}\left(w+z,q\right)\theta_{3}\left(w-%
z,q\right)={\theta_{4}}^{2}\left(w,q\right){\theta_{3}}^{2}\left(z,q\right)-{%
\theta_{1}}^{2}\left(w,q\right){\theta_{2}}^{2}\left(z,q\right),\]