[math] Add test and improve doxygen of finite difference methods#22823
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hageboeck wants to merge 5 commits into
Open
[math] Add test and improve doxygen of finite difference methods#22823hageboeck wants to merge 5 commits into
hageboeck wants to merge 5 commits into
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Test Results 23 files 23 suites 3d 10h 22m 19s ⏱️ Results for commit 2ba8357. |
dpiparo
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Jul 16, 2026
ferdymercury
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Jul 16, 2026
ferdymercury
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Thanks a lot!
I'd suggest
- adding in the RelNotes of 6.38.x and 6.40.2 that using Laplacian lead to incorrect results.
- fix preexisting TMathTests to not exit 0 and multiply by four refvalues
The standard second-order central, backward and forward differences contained a mistake: a factor-of-4 error. See finite different coefficients here: https://en.wikipedia.org/wiki/Finite_difference_coefficient
Use a polynomial and its known derivatives to check the correctness of the finite difference methods.
The test failed without any consequences because it was always returning 0. Other "tests" in this file will need to be updated to check their outputs in the future. Furthermore: - The second derivatives are unstable with short, so remove it from the test. - The targets for the second derivatives were wrong by a factor 4; fix. - Due to rounding, finite differences on integers don't exactly hit the target. Allow a delta of 1.
ferdymercury
approved these changes
Jul 16, 2026
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Note: Contains commits of #22809.