Hello all,

I have the following (probably quite elemntary) question, for those who might be able to help:

I scan a theoretical model’s parameter space (suppose 2-dimensional) to calculate corresponding chisquares among the model’s prediction and experimental data. This is done through an external personnal Fortran code.

I store the results in a file under the form (par1, par2, chisquare) and then read the file with a small root macro to create ntuples.

What I want to do, is to plot iso-chisquare contours on a 2-dimensional plane. To say this better, draw a smooth line connecting all the points with a given chisquare (of course the scan is done over a grid, so I guess a surface should first be generated in the 3D(par1, par2, chisquare) space, then a cut at a certain level and do a 2D projection of the cut).

If possible, I would also like to color the inside of the contours.

I guess I should use TGraphs (at first 3D and then 2D for the projection), since I’m not dealing with variables that could correspond to some sort of histogram.

Could somenoe help? By the way, to my knowledge there are really many theorists who have the same question!

Thanks a lot,

Andreas