Directional statistics - Entropy of wrapped normal (Jacobi theta) distribution

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SUMMARY

The discussion focuses on calculating the differential entropy of the wrapped normal distribution, specifically using the Jacobi theta function. The wrapped distribution is defined as p_w(θ) = ∑_{n=-∞}^∞ p(θ + 2πn), which is periodic with a period of 2π. The entropy formula is given by H = -∫_Γ p_w(θ) ln[p_w(θ)] dθ, where Γ is an interval of length 2π. The wrapped normal distribution with zero mean is represented as p_w(θ) = (1/2π) * θ_3(θ/2, e^{-σ²/2}), where θ_3 is the Jacobi theta function. Users are seeking guidance on calculating this entropy, as Mathematica does not provide sufficient assistance.

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  • Understanding of probability distributions, specifically the wrapped normal distribution.
  • Familiarity with Jacobi theta functions and their properties.
  • Knowledge of differential entropy and its mathematical formulation.
  • Experience with numerical integration techniques for complex functions.
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  • Research the properties and applications of Jacobi theta functions in statistical mechanics.
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If p(x) is a probability distribution on the real number line, the "wrapped" distribution around the unit circle is:
p_w(\theta)=\sum_{n=-\infty}^\infty p(\theta+2\pi n)
which is periodic with period 2π. The (differential) entropy is:
H=-\int_\Gamma p_w(\theta)\ln[p_w(\theta)]\,d\theta
where \Gamma is any interval of length 2π. I am having trouble finding the entropy for the wrapped normal distribution. For the wrapped normal distribution with zero mean,
p_w(\theta)=\frac{\vartheta _3\left(\frac{\theta }{2},e^{-\frac{\sigma ^2}{2}}\right)}{2 \pi }
which is in Mathematica notation, \vartheta _3(\cdot) is the Jacobi theta function:
\vartheta _3(u,q)=1+2\sum_{n=1}^\infty q^{n^2}\cos(2nu)
Is anyone familiar enough with Jacobi theta functions to give some guidance in calculating the entropy? Mathematica is not giving much help.
 
Last edited:
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You'd be lucky if a closed form expression exists. Perhaps try numerical integration or an asymptotic expansion?
 

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