stan-dev / stan-dev/math

generalize Eigen NumTraits specializations for decay types

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feature
Dominant language
C++
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839
Forks
220
Avg merge
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Merged PRs (30d)
14

Description

Description

Our specialization of Eigen's NumTraits class hardcodes stan::math::var. If instead we template on a type T then require a var on the decayed type of T, this will generalize to const and reference qualified variables.

At that point, the base_type tests can be extended to things like Eigen::Matrix<const var, -1, -1>.

Current Version:

v3.1.0

Contributor guide

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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

Locate the Eigen NumTraits specialization that currently names stan::math::var and the existing base_type tests. Read how the specialization determines its base type, then review the related Eigen and autodiff type behavior. Done means the specialization handles decayed const and reference-qualified variables and the tests cover cases such as Eigen::Matrix<const var, -1, -1>.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp
Domain
backend
Issue type
Refactor
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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