Re: [ROOT] No more TMatrix::EigenVectors(TVector&) method?

From: Edmond Offermann (
Date: Mon Mar 01 2004 - 15:28:20 MET


TMatrixD EigenVectors(TVectorD &eigenVal) has 
disappeared from the TMatrixD class (also the single-
precision version from TMatrix)

We have implemented new classes to deal with

TMatrixDEigen   : eigen values/vectors of a real
TMatrixDSymEigen: eigen values/vectors of a real
                  symmetric matrix .

How to use them:

TMatrixDSymEigen eigen (m);
TVectorD eigenVal    = eigen.GetEigenValues();
TMatrixD eigenMatrix = eigen.GetEigenMatrix();

We have tried to disentangle the matrix operations .
BLAS operations stayed in the matrix class while
linear algebra stuff like eigen analysis and
decompositions got their own classes .

This should help the user to navigate through the
operations . For instance, the previous implementation
had the eigen analysis in the matrix class while it
could only handle symmetric cases !


--- daniel cussol <> wrote:
> Hello rooters,
>  I tried to compile home made classes which use the
> TMatrix class to get 
> eigen vectors and eigen values of a matrix. Up to
> version v3.10.02 all 
> was OK, but since v4.00.02, the TMatix::EigenVectors
> method seems to 
> have disappeared! It is quite annoying since I use
> this method in 
> several other methods, and I do not want to rewrite
> all  of them (and I 
> SHOULD NOT DO). Has this method been fogotten?
>  Thanks for your help.
> -- 
> Daniel CUSSOL
> LPC Caen IN2P3/ENSICAEN/Universite de Caen
> Boulevard du Marechal Juin
> 14050 CAEN CEDEX
> e-mail :
> Tel    : +33-(0)2-31-45-29-73
> FAX    : +33-(0)2-31-45-25-49

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