Digital Library of Mathematical Functions
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20 Theta FunctionsProperties

§20.4 Values at z = 0

Contents

§20.4(i) Functions and First Derivatives

20.4.1\mathop{\theta_{{1}}\/}\nolimits\!\left(0,q\right)={\mathop{\theta_{{2}}\/}%
\nolimits^{{\prime}}}\!\left(0,q\right)={\mathop{\theta_{{3}}\/}\nolimits^{{%
\prime}}}\!\left(0,q\right)={\mathop{\theta_{{4}}\/}\nolimits^{{\prime}}}\!%
\left(0,q\right)=0,
20.4.2{\mathop{\theta_{{1}}\/}\nolimits^{{\prime}}}\!\left(0,q\right)=2q^{{1/4}}%
\prod\limits_{{n=1}}^{{\infty}}\left(1-q^{{2n}}\right)^{3},
20.4.3\mathop{\theta_{{2}}\/}\nolimits\!\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\mathop{\theta_{{3}}\/}\nolimits\!\left(0,q\right)=\prod\limits_{{n=1}}^{{%
\infty}}\left(1-q^{{2n}}\right)\left(1+q^{{2n-1}}\right)^{2},
20.4.5\mathop{\theta_{{4}}\/}\nolimits\!\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{\mathop{\theta_{{1}}\/}\nolimits^{{\prime}}}\!\left(0,q\right)=\mathop{\theta%
_{{2}}\/}\nolimits\!\left(0,q\right)\mathop{\theta_{{3}}\/}\nolimits\!\left(0,%
q\right)\mathop{\theta_{{4}}\/}\nolimits\!\left(0,q\right).

§20.4(ii) Higher Derivatives

20.4.7{\mathop{\theta_{{1}}\/}\nolimits^{{\prime\prime}}}(0,q)={\mathop{\theta_{{2}}%
\/}\nolimits^{{\prime\prime\prime}}}\!\left(0,q\right)={\mathop{\theta_{{3}}\/%
}\nolimits^{{\prime\prime\prime}}}\!\left(0,q\right)={\mathop{\theta_{{4}}\/}%
\nolimits^{{\prime\prime\prime}}}\!\left(0,q\right)=0.
20.4.8\frac{{\mathop{\theta_{{1}}\/}\nolimits^{{\prime\prime\prime}}}\!\left(0,q%
\right)}{{\mathop{\theta_{{1}}\/}\nolimits^{{\prime}}}\!\left(0,q\right)}=-1+2%
4\sum_{{n=1}}^{{\infty}}\frac{q^{{2n}}}{(1-q^{{2n}})^{2}}.
20.4.9\frac{{\mathop{\theta_{{2}}\/}\nolimits^{{\prime\prime}}}\!\left(0,q\right)}{%
\mathop{\theta_{{2}}\/}\nolimits\!\left(0,q\right)}=-1-8\sum_{{n=1}}^{{\infty}%
}\frac{q^{{2n}}}{(1+q^{{2n}})^{2}},
20.4.10\frac{{\mathop{\theta_{{3}}\/}\nolimits^{{\prime\prime}}}\!\left(0,q\right)}{%
\mathop{\theta_{{3}}\/}\nolimits\!\left(0,q\right)}=-8\sum_{{n=1}}^{{\infty}}%
\frac{q^{{2n-1}}}{(1+q^{{2n-1}})^{2}},
20.4.11\frac{{\mathop{\theta_{{4}}\/}\nolimits^{{\prime\prime}}}\!\left(0,q\right)}{%
\mathop{\theta_{{4}}\/}\nolimits\!\left(0,q\right)}=8\sum_{{n=1}}^{{\infty}}%
\frac{q^{{2n-1}}}{(1-q^{{2n-1}})^{2}}.
20.4.12\frac{{\mathop{\theta_{{1}}\/}\nolimits^{{\prime\prime\prime}}}\!\left(0,q%
\right)}{{\mathop{\theta_{{1}}\/}\nolimits^{{\prime}}}\!\left(0,q\right)}=%
\frac{{\mathop{\theta_{{2}}\/}\nolimits^{{\prime\prime}}}\!\left(0,q\right)}{%
\mathop{\theta_{{2}}\/}\nolimits\!\left(0,q\right)}+\frac{{\mathop{\theta_{{3}%
}\/}\nolimits^{{\prime\prime}}}\!\left(0,q\right)}{\mathop{\theta_{{3}}\/}%
\nolimits\!\left(0,q\right)}+\frac{{\mathop{\theta_{{4}}\/}\nolimits^{{\prime%
\prime}}}\!\left(0,q\right)}{\mathop{\theta_{{4}}\/}\nolimits\!\left(0,q\right%
)}.