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