Fix accurate AD summation in residual equations#1035
Open
Debraheem wants to merge 1 commit into
Open
Conversation
Contributor
|
LGTM but |
Contributor
|
Not sure if you just need to rebase/merge |
Member
Author
|
yeah, i plan to take a closer look soon as well. Might just need to merge main in. |
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
I believe the accurate AD summation types in mesa's residual equations were just being assigned the result of a normal AD expression sum, so the (dp) cancellation had already happened before the compensated summation logic even runs. So the accurate AD summation was not really being leveraged at all. I would call this an inconsequential bug, but fixing it could yield benefits.
This pr fixes the accurate AD sums to accumulate term-by-term through the accurate type, so each add/subtract actually uses the compensation algorithm. I added this type to a couple other locations where it might make sense (summing sources in hydro energy and in RSP2 turbulent energy and luminosity equations), and I did some minor clean up.
I'm not sure if this will help mesa convergence or not, it could in principle, but the point remains: this branch makes the intended behavior on main actually happen in practice. We will have to test and see if any thing changes in practice...