Re: [ROOT] EigenValues

From: Edmond Offermann (edmondoffermann@yahoo.com)
Date: Wed Sep 17 2003 - 03:51:20 MEST


Hi John,

Attached to this mail is a modified macro.
main change is the TMatrix/TVector constructor:
TMatrix matrix[NBINS][NBINS] => TMatrix
matrix(NBINS,NBINS), the same for TVector

Eddy

--- "Dr. John Krane" <jkrane@netzero.com> wrote:
> Hi,
> 
> I'm trying to find the eigen-stuff of a matrix. 
> Following the info in 
> the root/test/*.cxx files and what I can find
> online, I'm doing:
> 
>    TMatrix tcovmat[NBINS][NBINS];
> 
>    for (Int_t i=1;i<NBINS;i++) {
>      for (Int_t j=1;j<=i;j++) {
> 	... blah blah computing the elements of the
> matrix...
>        tcovmat[i][j]=aaa;
>        tcovmat[j][i]=aaa; //symmetric
>      }
>    }
>    TVector eigenvalues[NBINS];
>    TMatrix eigenvectors[NBINS][NBINS];
>    eigenvectors = tcovmat.EigenVectors(eigenvalues);
> 
> But this code makes the compiler unhappy:
> 
> find_vr.C:237: request for member `EigenVectors' in
> `tcovmat', which is 
> of non-aggregate type `TMatrix[((NBINS - 1) +
> 1)][((NBINS - 1) + 1)]'
> 
> This message seems a bit cryptic to me, and I
> thought I was using the 
> method correctly.  Could somebody please tell me
> what I'm doing wrong?
> 
> 	- John
> 
> -- 
> 
> Dr. John Krane
> jkrane@netzero.com
> 
> 




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