\[\theta_{2}\left(4z\middle|4\tau\right)=B\theta_{2}\left(\tfrac{1}{8}\pi-z%
\middle|\tau\right)\theta_{2}\left(\tfrac{1}{8}\pi+z\middle|\tau\right)\*%
\theta_{2}\left(\tfrac{3}{8}\pi-z\middle|\tau\right)\theta_{2}\left(\tfrac{3}{%
8}\pi+z\middle|\tau\right),\]