stan-dev / stan-dev/docs

discuss propto with double vs. autodiff variables in User's Guide

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enhancement
Dominant language
TeX
Stars
43
Forks
133
Avg merge
11h 32m
Merged PRs (30d)
4

Description

Summary:

In the User's Guide chapter on efficiency, we should discuss the tradeoff between evaluating propto=true with double and autodiff variables.

Description:

The issue is that

  • propto=true requires us to compute autodiff in order to drop normalizing constant calculations (we drop ones that aren't autodiff vars)
  • propto=false requires computation of normalizing constants over double, but no autodiff

For double input, either of these can be faster depending on how expensive the normalizing constants are to compute

Current Version:

v2.32

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Research direction

Start with the User's Guide chapter on efficiency and locate the discussion of propto=true and propto=false for double and autodiff variables. Add the requested tradeoff discussion, explaining when each approach may be faster, and verify the rendered documentation and relevant source changes.

Written by the indexing model from the issue text.

Assessment

Tech stack
tex
Domain
documentation
Issue type
Documentation
Difficulty
2/5
Estimated time
1-3 hours
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
45/100

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