View Issue Details
| ID | Project | Category | View Status | Date Submitted | Last Update |
|---|---|---|---|---|---|
| 0002486 | OpenFOAM | Bug | public | 2017-03-05 12:10 | 2017-04-20 11:03 |
| Reporter | hertzsprung | Assigned To | will | ||
| Priority | normal | Severity | minor | Reproducibility | always |
| Status | resolved | Resolution | fixed | ||
| Platform | GNU/Linux | OS | Ubuntu | OS Version | 16.10 |
| Product Version | dev | ||||
| Summary | 0002486: Singular value decomposition of singular matrix returns nans | ||||
| Description | The attached application returns a psuedo-inverse that is all nans. The same operation in python3-numpy gives the expected result. | ||||
| Tags | No tags attached. | ||||
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Can you provide a patch to fix this problem? |
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Here is some basic info about NumPy: https://www.everipedia.com/NumPy/ |
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Your test program needs to construct the SVD class after setting the matrix coefficients. The decomposition is done on construction, not at the point of generating the pseudo-inverse. The bug report was still valid, though. I don't fully understand the SVD code, but I found a product that was under-flowing, which was later used in a division. I've added protection to these operations as of commit 646a269217d1558bb67386a8721c0ca5d50830c0. The matrix in your test routine now doesn't generate any NaNs, so I'm considering this bug resolved. The pseudo-inverse still isn't exactly the same as numpy or octave, though. I don't know whether that's a bug, or if it is to be expected for a matrix this badly conditioned. |
| Date Modified | Username | Field | Change |
|---|---|---|---|
| 2017-03-05 12:10 | hertzsprung | New Issue | |
| 2017-03-05 12:10 | hertzsprung | File Added: testSingularSVD.tar.gz | |
| 2017-03-05 12:32 | henry | Note Added: 0007854 | |
| 2017-04-08 00:41 | travm1 | Note Added: 0008022 | |
| 2017-04-20 11:03 | will | Assigned To | => will |
| 2017-04-20 11:03 | will | Status | new => resolved |
| 2017-04-20 11:03 | will | Resolution | open => fixed |
| 2017-04-20 11:03 | will | Note Added: 0008035 |
