Some doubts on Contour Plots

[Wile_E_Coyote]

Regarding the fit of the data

In ROOT, you are expected to provide reasonable initial values of all fit parameters (except for some “built-in” functions, like “gaus”, for which the standard fit procedure can automatically “guess” them). Get used to it. Note: if you need to swap “X” and “Y” columns, you can try: TGraph *gYX = new TGraph("ev7.dat"); TGraph *g = new TGraph(gYX->GetN(), gYX->GetY(), gYX->GetX()); delete gYX; // no longer needed