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Geometric nested sampling: sampling from distributions defined on non-trivial geometries

Published version
Peer-reviewed

Type

Article

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Abstract

Metropolis Hastings nested sampling evolves a Markov chain, accepting new points along the chain according to a version of the Metropolis Hastings acceptance ratio, which has been modified to satisfy the nested sampling likelihood constraint. The geometric nested sampling algorithm I present here is based on the Metropolis Hastings method, but treats parameters as though they represent points on certain geometric objects, namely circles, tori and spheres. For parameters which represent points on a circle or torus, the trial distribution is “wrapped” around the domain of the posterior distribution such that samples cannot be rejected automatically when evaluating the Metropolis ratio due to being outside the sampling domain. Furthermore, this enhances the mobility of the sampler. For parameters which represent coordinates on the surface of a sphere, the algorithm transforms the parameters into a Cartesian coordinate system before sampling which again makes sure no samples are automatically rejected, and provides a physically intuitive way of the sampling the parameter space.

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Keywords

46 Information and Computing Sciences

Journal Title

The Journal of Open Source Software (JOSS)

Conference Name

Journal ISSN

2475-9066
2475-9066

Volume Title

Publisher

The Open Journal