Check that equivalent cells compile a form the same way - #5375
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Imperial have culled a bunch of old accounts.
The latest release breaks loopy. --------- Co-authored-by: Claude Opus 5 <noreply@anthropic.com> Co-authored-by: Connor Ward <c.ward20@imperial.ac.uk>
A hexahedron and a quadrilateral times an interval hold the same space, so the same form must reach the same kernel on both. Firedrake issue 5223 left them apart: the quadrature degree UFL estimates comes from the element's embedded superdegree, which a tensor product element summed over its factors instead of taking per direction, so every cell built as a tensor product was integrated at too high a degree. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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--------- Co-authored-by: Claude Opus 5 <noreply@anthropic.com>
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Closes the discrepancy left over from #5223. A hexahedron and a quadrilateral times an interval hold the same space, but the same form did not reach the same kernel on the two cells:
UFL estimates a quadrature degree from the element's embedded superdegree. A tensor product element summed that over its factors, so
Q3 x P3reported 6 where the hexahedralQ3reported 3, and every cell built as a tensor product was integrated at too high a degree. The overshoot compounds with nesting:interval x interval x intervalcosts 8.5x the hexahedral flop count at degree 3, against 3.9x forquadrilateral x interval.test_equivalent_cellscompiles the Helmholtz form and its action on each pair of equivalent cells and asserts the flop counts agree. All six parametrisations fail onmainand pass with firedrakeproject/fiat#287.The fix itself is in FIAT (firedrakeproject/fiat#287, branch
pbrubeck/tp-embedded-superdegree) and in UFL (FEniCS/ufl#506, merged), which stops reducing the estimated degree on cells that are not simplices.Stacked on #5377, which is needed for the test suite to run at all.
DROP BEFORE MERGE
The second commit installs the FIAT branch over the pinned
mainafter CI has installed everything else. Drop it once firedrakeproject/fiat#287 merges.AI was used in preparing this contribution (Claude Code).
🤖 Generated with Claude Code