Re: 3D interpolation

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
>
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-- 
Dr. Otto Schaile            Department f"ur Physik, LMU M"unchen
Phone: +49 89 289 14070     Am Coulombwall 1, D-85748 Garching, Germany
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FAX:   +49 89 289 14072     EMail: Otto.Schaile_at_Physik.Uni-Muenchen.DE