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20 Theta FunctionsProperties20.3 Graphics
Figure 20.3.2 (See in context.)
See accompanying text
Figure 20.3.2: \theta_{1}\left(\pi x,q\right), 0\leq x\leq 2, q = 0.05, 0.5, 0.7, 0.9. For q\leq q^{\text{Dedekind}}, \theta_{1}\left(\pi x,q\right) is convex in x for 0<x<1. Here q^{\text{Dedekind}}=e^{-\pi y_{0}}=0.19 approximately, where y=y_{0} corresponds to the maximum value of Dedekind’s eta function \eta\left(iy\right) as depicted in Figure 23.16.1.