stan-dev / stan-dev/math

Add inverse Gaussian distribution support

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Dominant language
C++
Stars
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Forks
220
Avg merge
2d 4h
Merged PRs (30d)
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Description

Description

Analogous to other distributions, add support for the inverse Gaussian distribution with a sampling statement and Stan functions for working with its log density, CDF, and CCDF.

This can be a wrapper around the Boost implementation of the distribution.

Example

The motivation is from writing a GLM with an inverse Gaussian. Similar to rstanarm, I implemented a custom helper function to perform the likelihood computation and it seems like other people in the past have re-implemented the same set of algorithms. For example, see here and here. It would be nice to have this as a library function.

Current Version:

v4.4.0

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reviewing the Boost inverse Gaussian distribution documentation and the analogous helper in rstanarm's src/stan_files/functions/continuous_likelihoods.stan. Compare the requested wrapper with existing distribution support, then verify that it provides a sampling statement and Stan functions for log density, CDF, and CCDF.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp
Domain
backend
Issue type
Feature
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
48/100

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