How can in a TH2D the scale on both axis be set to the same value, so that if I have lets say 100 cm on one axis and 150cm on the other axis the TH2D plot is really plotted in that ratio (1 : 1.5) and not as a square? A centimeter on one axis has to have the same “length” as on the other axis…
I tried SetFixedAspectRatio and SetRangeUser but with no success…

[code]{
//method1. compute ymax to get a commensurate range
// 1 pixel must correspond to the same range in x and y
TCanvas c1(“c1”,“c1”,10,10,800,600);
Float_t xmin = 0;
Float_t xmax = 20;
Float_t ymin = -2;
Int_t npx = gPad->GetWw();
Int_t npy = gPad->GetWh();
Float_t ymax = ymin + (xmax-xmin)*npy/npx;
TH2F h(“h”,"",20,xmin,xmax,20,ymin,ymax);
h.Draw();
TArc a1(6,4,6);
a1.Draw();

//method2. set a square virtual canvas size in a non-square canvas
TCanvas c2(“c2”,“c2”,200,50,800,600);
c2.SetCanvasSize(700,700);
c2.DrawFrame(0,0,20,20);
TArc a2(10,10,10);
a2.Draw();
}
[/code]

Thanks a lot for the quick answer. In principle it seems to work, but as you might see in the attached pictures, now I have a big area where no data exists. So my question is: Can I “cut away” this from the pad? I just want to see the values up to 200 on the xaxis without loosing the scale again…

Another thing: Is it possible to have the point of origin at another place? In this case, the y values (shown above in the picture) should increase from top top bottom. So the point (0,0) should be in the upper left corner. One could say I want to “mirror” the picture along the x axis (but the x axis can be at the bottom or top…)