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20 Theta FunctionsProperties

§20.4 Values at z = 0

Contents
  1. §20.4(i) Functions and First Derivatives
  2. §20.4(ii) Higher Derivatives

§20.4(i) Functions and First Derivatives

20.4.1 \theta_{1}\left(0,q\right)=\theta_{2}'\left(0,q\right)=\theta_{3}'\left(0,q%
\right)=\theta_{4}'\left(0,q\right)=0,
20.4.2 \theta_{1}'\left(0,q\right)=2q^{1/4}\prod\limits_{n=1}^{\infty}\left(1-q^{2n}%
\right)^{3}=2q^{1/4}{\left(q^{2};q^{2}\right)_{\infty}}^{3},
20.4.3 \theta_{2}\left(0,q\right)=2q^{1/4}\prod\limits_{n=1}^{\infty}\left(1-q^{2n}%
\right)\left(1+q^{2n}\right)^{2},
20.4.4 \theta_{3}\left(0,q\right)=\prod\limits_{n=1}^{\infty}\left(1-q^{2n}\right)%
\left(1+q^{2n-1}\right)^{2},
20.4.5 \theta_{4}\left(0,q\right)=\prod\limits_{n=1}^{\infty}\left(1-q^{2n}\right)%
\left(1-q^{2n-1}\right)^{2}.

Jacobi’s Identity

20.4.6 \theta_{1}'\left(0,q\right)=\theta_{2}\left(0,q\right)\theta_{3}\left(0,q%
\right)\theta_{4}\left(0,q\right).

§20.4(ii) Higher Derivatives

20.4.7 \theta_{1}''\left(0,q\right)=\theta_{2}'''\left(0,q\right)=\theta_{3}'''\left(%
0,q\right)=\theta_{4}'''\left(0,q\right)=0.
20.4.8 \frac{\theta_{1}'''\left(0,q\right)}{\theta_{1}'\left(0,q\right)}=-1+24\sum_{n%
=1}^{\infty}\frac{q^{2n}}{(1-q^{2n})^{2}}.
20.4.9 \frac{\theta_{2}''\left(0,q\right)}{\theta_{2}\left(0,q\right)}=-1-8\sum_{n=1}%
^{\infty}\frac{q^{2n}}{(1+q^{2n})^{2}},
20.4.10 \frac{\theta_{3}''\left(0,q\right)}{\theta_{3}\left(0,q\right)}=-8\sum_{n=1}^{%
\infty}\frac{q^{2n-1}}{(1+q^{2n-1})^{2}},
20.4.11 \frac{\theta_{4}''\left(0,q\right)}{\theta_{4}\left(0,q\right)}=8\sum_{n=1}^{%
\infty}\frac{q^{2n-1}}{(1-q^{2n-1})^{2}}.
20.4.12 \frac{\theta_{1}'''\left(0,q\right)}{\theta_{1}'\left(0,q\right)}=\frac{\theta%
_{2}''\left(0,q\right)}{\theta_{2}\left(0,q\right)}+\frac{\theta_{3}''\left(0,%
q\right)}{\theta_{3}\left(0,q\right)}+\frac{\theta_{4}''\left(0,q\right)}{%
\theta_{4}\left(0,q\right)}.