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IDProjectCategoryView StatusLast Update
0001373OpenFOAMBugpublic2014-08-28 11:30
Reporteruser982Assigned Towill  
PrioritynormalSeveritymajorReproducibilityalways
Status resolvedResolutionfixed 
PlatformLinuxOSOtherOS Version(please specify)
Summary0001373: Bug in eigen vector computation of tensor (2.3.0)
Description1) the eigenvector computation returns zero vectors in case of multiple eigenvalues


2) Another problem seems to exist with the sensitivy of the symmetry check. It occurs quite often, that matrices which are supposed to be symmetric, but are slightly off due to numerical errors produce zero vectors:
This is not covered by the attached test, but seems to originate from
/src/OpenFOAM/primitives/Tensor/tensor/tensor.C:179

Steps To Reproducemodified tensor test shows the problem. see attached file which creates the following output:

tensor 1: (0.333 0 0 0 0.333 0 0 0 0.333)
tensor 2: (0.333 0 0 0 0.333 0 0 0 0.335)
tensor 3: (0.333 0 0 0 0.334 0 0 0 0.335)
eigenvalues 1: (0.333 0.333 0.333)
eigenvalues 2: (0.333 0.333 0.335)
eigenvalues 3: (0.333 0.334 0.335)
eigenvectors 1: (0 0 0 0 0 0 0 0 0)
eigenvectors 2: (0 0 0 0 0 0 0 0 1)
eigenvectors 3: (1 0 0 -0 1 -0 0 0 1)



  
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user982

2014-08-14 14:38

 

tensor_bug.tgz (541 bytes)

will

2014-08-28 11:30

manager   ~0003221

Thanks for the report. This has been fixed in commits 50b81a7 and 68fcd7a so that repeated roots of the characteristic polynomial are now handled. Your tensors, as well as a number of other awkward ones, are now computed correctly. It's a significant rewrite, though, so there may be some bugs. Please report back if you have any issues.

Issue History

Date Modified Username Field Change
2014-08-14 14:38 user982 New Issue
2014-08-14 14:38 user982 File Added: tensor_bug.tgz
2014-08-28 11:30 will Note Added: 0003221
2014-08-28 11:30 will Status new => resolved
2014-08-28 11:30 will Resolution open => fixed
2014-08-28 11:30 will Assigned To => will