Log of /trunk/math/matrix/src/TMatrixTCramerInv.cxx
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22885 -
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Modified
Fri Mar 28 13:57:25 2008 UTC (6 years, 9 months ago) by
rdm
File length: 57626 byte(s)
Diff to
previous 20882
move the following directories under the new "math" meta directory:
mathcore
mathmore
fftw
foam
fumili
genvector
matrix
minuit
minuit2
mlp
physics
smatrix
splot
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16458 -
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Modified
Fri Oct 6 06:52:34 2006 UTC (8 years, 3 months ago) by
brun
Original Path:
trunk/matrix/src/TMatrixTCramerInv.cxx
File length: 57697 byte(s)
Diff to
previous 15888
From Eddy Offermann:
Previously, the matrix package contained a large amount of ASSERT
statements which are a nuisance for programs analyzing a series of
independent events like in high-energy physics .
Assert's were issued when for instance a division by zero was requested
or a matrix was invalid . Most algorithms made matrices/vectors invalid
after an error occured in an operation , like inversion of a singular matrix .
Unfortunately, not all assert's were accompanied by error messages .
This situation has been completely overhauled :
- All error conditions in the algorithms are now accompanied by error
messages .
- In all algorithms it is still asserted that vectors/matrices are
valid BUT only in very few cases is a matrix/vector made invalid :
for instance if memory is allocated with incorrect parameters .
- In case of division by zero, the division is skipped . In case of a
singular matrix, the inversion routine returns the original matrix .
In the past the result of an inversion could be checked through the
value of the returned determinant or checking whether the inverted matrix
was valid .
Since from now on, we never make the matrix invalid in this operation, the
latter check will not indicate a singular matrix anymore .
The decompostion classes TDecomp... have a backward-compatible
change in the interface which makes detection of singularity easier :
old interface :
void Invert (TMatrixD &inv);
TMatrixD Invert ();
new interface :
Bool_t Invert (TMatrixD &inv);
TMatrixD Invert (Bool_t &status);
TMatrixD Invert () { Bool_t status; return Invert(status);
}
The returned status is kFALSE in case of singularity .
The old situation is easily reproduced by setting the ROOT variable
gErrorAbortLevel to kError . This cause an exception when there is an error
message (Error...) ., In the past the matrix would be made invalid which
would cause the next operation to throw an exception .
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