RE: [ROOT] Compute the determinant and invert a covariance matrix

From: Pierre-Luc Drouin (pldrouin@physics.carleton.ca)
Date: Sat Jul 12 2003 - 22:14:14 MEST


Hi,

It really helps for the matrix inversion. What should I use for the
determinant?

Thank you!

Pierre-Luc Drouin

On Sat, 12 Jul 2003, Valeri Fine wrote:

> Check out the class:
> http://root.cern.ch/root/htmldoc/TCL.html 
> 
> See documentation:
> http://wwwinfo.cern.ch/asdoc/shortwrupsdir/f112/top.html 
> http://wwwasdoc.web.cern.ch/wwwasdoc/shortwrupsdir/f110/top.html 
> 
>         Hope this helps, Valeri
> 
> > -----Original Message-----
> > From: owner-roottalk@pcroot.cern.ch
> [mailto:owner-roottalk@pcroot.cern.ch]
> > On Behalf Of Pierre-Luc Drouin
> > Sent: Saturday, July 12, 2003 5:02 PM
> > To: roottalk@pcroot.cern.ch
> > Subject: [ROOT] Compute the determinant and invert a covariance matrix
> > 
> > Hello,
> > 
> > I've to compute the determinant and to invert a matrix in order to
> > evaluate density probabilities in a multi-gaussian distribution. So
> the
> > matrix is symmetric, and diagonal terms are 2-3 order of magnitudes
> bigger
> > than off-diagnoal terms. I want to minimize the error of truncature on
> > determinant and inverse matrix. What should I use instead of
> > TMatrix::Invert ?
> > 
> > Thank you!
> > 
> > Pierre-Luc Drouin
> 



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