Fill area delimited by a TF1 and specific axes ranges

[segonzal]

Hello,

I’d like to fill the area between a TF1 in specific axes ranges. From the example attached, I’d like to fill the area under the red-curve in the range 0<x<40 and 0<y<200.

Any suggestion how to achieve this ?

Thanks in advance

fa.C (445 Bytes)

[Axel]

Hi,

  TF1* f1Range = (TF1*)f1->Clone("f1Range");
  f1Range->SetRange(0., 40.);
  f1Range->SetFillColor(kRed);
  f1Range->SetFillStyle(1001);
  f1Range->Draw("SAME FC");

might help? I.e. create a clone of the function, reduce its range, and draw that with fill style.

Axel.

[segonzal]

Hi Axel,

thanks a lot for the suggestion. Yes, that works for the x-axis, but what about the y-range ? In the example, I’d just like the area underneath the curve and the straight-line y=k (k=200 in this case) to be filled.

Not sure if there’s a way to redefine my function to be something like (a,b,k being constants):

• if 0 < x <= a: y(x)=k
• if x >a: y(x) = b/x

??

Sergio

[couet]

Here is a macro doing what you requested: fa2.C (630 Bytes)

[segonzal]

Indeed… I should have thought about that way. Thanks for the simplicity Olivier !

[couet]

Sergio also not the use of “DrawFrame” in the macro I sent. It is "the way’ to define an empty frame with axis. The way you did it with an empty 2D histogram also works but it is heavier…

[segonzal]

Yes, indeed, that’s an interesting option for quick plots. I use the empty 2D histo to define the style (axes titles, fonts, sizes, etc.); for the example I posted at the beginning I just removed everything related to style… I would think using the “DrawFrame” and modifying the TH1F it gives access to would be equivalent at the end ? The other option is to use a TStyle, which I also have but just use from time to time and varies from project to project…

[couet]

DrawFrame returns a TH1F so you can apply all the setting you need on it.