Fix NaN handling in electrostatic_sphere_eb MR analysis#6807
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ax3l merged 1 commit intoBLAST-WarpX:developmentfrom Apr 28, 2026
Merged
Fix NaN handling in electrostatic_sphere_eb MR analysis#6807ax3l merged 1 commit intoBLAST-WarpX:developmentfrom
ax3l merged 1 commit intoBLAST-WarpX:developmentfrom
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The find_first_non_zero_from_bottom_left/upper_right helper functions used ``matrix[i][j] != np.nan`` to skip NaN values. Per IEEE 754, NaN != NaN is always True, so this check never filtered out NaN cells. On GPU platforms where openpmd outputs NaN for cells outside the refined patch (rather than zero), the analysis selected NaN regions as valid data, producing ``nan`` errors for level 1 and failing the assertion. Fix: replace ``!= np.nan`` with ``not np.isnan()``. With the fix, level 1 errors on A100 GPU are 0.029% (phi) and 0.083% (Er), well within the 0.4% tolerance. Co-Authored-By: Claude Opus 4.7 <[email protected]>
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Summary
In IEEE floats,
np.nan != np.nanis alwaysTrue, so the old code was buggy:NaN is never equal to anything, including itself.
Original Description - Spotted by @zippylab
The find_first_non_zero_from_bottom_left/upper_right helper functions used
matrix[i][j] != np.nanto skip NaN values. Per IEEE 754, NaN != NaN is always True, so this check never filtered out NaN cells.On GPU platforms where openpmd outputs NaN for cells outside the refined patch (rather than zero), the analysis selected NaN regions as valid data, producing
nanerrors for level 1 and failing the assertion.Fix: replace
!= np.nanwithnot np.isnan().With the fix, level 1 errors on A100 GPU are 0.029% (phi) and 0.083% (Er), well within the 0.4% tolerance.
X-ref
Isolated from #6801