Conversation
Add make_projected_bubble_moment, which projects the bubble onto
polynomials of the given degree and drops the components of lower
degree. What remains is orthogonal to P_{degree-1} and invariant under
the symmetry group of the cell, which is what a constraint functional
annihilating that lower-degree space needs of its weight.
Bernardi-Raugel builds its tangential constraint weight this way
already; move that construction into the helper. Its own scaling is
invariant under the helper's normalization, so the weight is unchanged.
Walkington's face constraint was a cubic interpolating [0, 0, 0, 1] at
four quadrature points, with the rule then truncated to the points where
the result happened to be nonzero. That weight is invariant under the
three rotations of the face but not under the reflections. The
projected bubble is the unique symmetric cubic orthogonal to P_2, so the
truncation is no longer available: the face rule goes from 6 points to
12. The constraint dofs are discarded before the FInAT dual basis is
built, so this is paid once at element construction.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
pbrubeck
commented
Sep 18, 2026
pbrubeck
force-pushed
the
pbrubeck/gn-moments
branch
from
September 22, 2026 18:47
bc452f7 to
960284f
Compare
rckirby
requested changes
Sep 23, 2026
rckirby
left a comment
rckirby
left a comment
There was a problem hiding this comment.
It would help me reviewing if you would put in a description to the PR -- is this a clean-up exercise, fixing something that was broken, or adding a new feature? I thought we already had BR and Walkington working?
Author
Description updated. This is just a cleanup for BR and Walkington, and facilitates imposing higher degree face constraints or getting hierarchical face bubbles for future elements. |
rckirby
self-requested a review
September 23, 2026 21:36
rckirby
approved these changes
Sep 23, 2026
rckirby
left a comment
rckirby
left a comment
There was a problem hiding this comment.
Thanks for clarifying in the comments, etc.
This branch has not been deployed
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.
Moments that enforce degree constraints are now against symmetric functions obtained by projecting a bubble into the set of homogeneous degree-k polynomials Pk \ P_{k-1}.
(1 - proj_{k-1}) bubble_k = sum_j c_j q_j for q_j in Pk \ P_{k-1}
This is merely a cleanup and does not affect the nodal bases for the elements affected.