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. Author manuscript; available in PMC: 2021 Sep 16.
Published in final edited form as: Phys Rev X. 2020 Jan 30;10(1):011021. doi: 10.1103/physrevx.10.011021

TABLE III.

Probability distributions used and their densities. Here, the corresponding random variables are denoted by x. We use ”;” to separate random variables from parameters. For example, Normal(x;μ,σ2) means that x is the random variable (e.g. +dx Normal(x;μ,σ2) = 1), and μ and σ2 are parameters characterizing this density.

Distribution Notation Probability density function Mean Variance
Normal Normal(μ,σ2) 12πσ2e(xμ)22σ2 μ σ 2
Symmetric Normal SymNormal(μ,σ2) 12e(x+μ)22σ22πσ2+12e(xμ)22σ22πσ2 0 μ2 + σ2
Exponential Exponential(μ) μeμx 1μ 1μ2
Chi-square χ2(α,2) 1Γ(α2)2α2xα21ex2 α 2α
Gamma Gamma(α,β) 1Γ(α)βαxα1exβ αβ αβ2
Inverse-Gamma InvGamma(α,β) βαΓ(α)xα1eβx βα1 β2(α1)2(α2)
Beta Beta(α,β) Γ(α+β)Γ(α)Γ(β)xα1(1x)β1 αα+β αβ(α+β)2(α+β+1)
Bernoulli Bernoulli(q) (q1)δ0(x)+qδ1(x) q q(1q)