Re: 3D interpolation

From: Christophe Delaere <delaere_at_fynu.ucl.ac.be>
Date: Tue, 26 Apr 2005 13:45:38 +0200


Hi,

If you need to fit your chi2 distribution, the Neural-Net method may be pretty usefull, especially if you don't want to give a physical meaning to the resulting function (as it seems in your case, as you just want to interpolate the points).

You may be interested by the second example there: http://www.fynu.ucl.ac.be/users/c.delaere/level2/MLP/

Cheers,
Christophe.

On Tuesday 26 April 2005 13:11, you wrote:
> Hello Otto,
> My problem is highly non gaussian and the Chi2 presents 2 local minimum
> reflecting the ambiguity of the physics involved. I will use some hints
> given by Rene and see if I can manage.
> See you
> Jean-Eric
>
> --On mardi 26 avril 2005 12:43 +0200 Otto Schaile
>
> <Otto.Schaile_at_Physik.Uni-Muenchen.DE> wrote:
> > Hi Jean-Eric,
> >
> > I would try to fit a TF2 (2-dim function) to the x,y, chi2 values
> > and then plot this function. The question is if you find a simple
> > function. Polynomials with high enough degree fit of course
> > everything.
> > If you want I can provide you with a simple 2 dim gauss.
> > When plotting the function you can adjust the number of contours
> > and the level heights by calls to:
> >
> > f1->SetContour(Int_t nlevels, const Double_t *levels)
> >
> > Cheers
> > Otto
> >
> > On Tue, 26 Apr 2005, Jean-Eric Campagne wrote:
> >> Dear developpers,
> >>
> >> I wander if you can help me in the following task: my final goal is to
> >> plot Chi2 contours in a 2 dimentions x-y plot.
> >>
> >> As a starting point, I have a table of Chi2_ij values for some (x_i,
> >> y_j) points. The contours are the location of (x,y) points where
> >> Chi2(x,y) = 10.64 (for definiteness).
> >>
> >> My problem is to get the (x,y) location that fullfill the above
> >> constraint, for that the Chi2 should be evaluated (interpolated) between
> >> the different (x_i,y_j,Chi2_ij) values.
> >>
> >> How ROOT can help me in this double task: 1) perform the interpolation
> >> to find the (x,y) that Chi2(x,y) = 10.64 and 2) plot the result?
> >>
> >> Regards
> >> J.E Campagne
> >>
> >> ........................................................................
> >> ... .LAL - IN2P3 - CNRS
> >> .LAL - B.P 34 - 91898 Orsay Cedex - France
> >> .Piece 108
> >> .Tel +33 (0)1 64 46 84 29
> >> .Fax +33 (0)1 64 46 83 97
> >> ........................................................................
> >> ...
> >
> > --
> > Dr. Otto Schaile Department f"ur Physik, LMU M"unchen
> > Phone: +49 89 289 14070 Am Coulombwall 1, D-85748 Garching, Germany
> > Mobil: +49 160 1553598
> > FAX: +49 89 289 14072 EMail: Otto.Schaile_at_Physik.Uni-Muenchen.DE
>
> ...........................................................................
> .LAL - IN2P3 - CNRS
> .LAL - B.P 34 - 91898 Orsay Cedex - France
> .Piece 108
> .Tel +33 (0)1 64 46 84 29
> .Fax +33 (0)1 64 46 83 97
> ...........................................................................

-- 
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Received on Tue Apr 26 2005 - 13:45:48 MEST

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