#729 Singularity detection in FieldMatrix' LU decomposition buggy
Metadata
| Property | Value |
|---|---|
| Reported by | Andreas Lauser (andreas.lauser@iws.uni-stuttgart.de) |
| Reported at | Jan 28, 2010 11:04 |
| Type | Bug Report |
| Version | Git (pre2.4) [autotools] |
| Operating System | Linux |
| Last edited by | Christian Engwer (christi@conan.iwr.uni-heidelberg.de) |
| Last edited at | Apr 29, 2011 11:43 |
| Closed by | Christian Engwer (christi@conan.iwr.uni-heidelberg.de) |
| Closed at | Apr 29, 2011 11:43 |
| Closed in version | Unknown |
| Resolution | Won't fix |
| Comment |
Description
The singularity detection in the FieldMatrix' LU decompostion throws an exception for the following matrix
1, 0, 0, 0 -3.02852e-07, 1, -0.00434667, 1.08683e-09 0, 0, 1, 0 -4248.83, -9.22043e+09, 0, 1
This is due to the fact, that the ratio between the largest and the smallest entry is 18 decimal orders of magnitute which is above machine precision of about 16 orders of magnitute.
On the other hand, the matrix clearly isn't singular and it emerges naturally from a physical problem.
Disabling the singularity detection makes the LU decomposition (and my model) work without any problems, which is due to the fact that very large and very small numbers are never added during the course of the decomposition.