update_scaled_gamma_poisson

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function update_scaled_gamma_poisson(x:Integer, a:Real, k:Real, θ:Real) -> (Real, Real)

Update the parameters of a scaled Gamma distribution with a Poisson likelihood.

• x: The variate.
• a: Scale.
• k: Prior shape.
• θ: Prior scale.

Returns: the posterior hyperparameters k' and θ'.