How to fill color in function?

Newbie
1

Hi, Everyone,

I want to fill color in function, then can ROOT do it?

I have sample code making the gaussian.

{
  TCanvas *c=new TCanvas();
  TF1 *f=new TF1("f", "TMath::Gaus(x)", -6, 6);
  f->Draw();
  return c;
}

For example, I want to fill color in the function region rom -1 to 1
I tried to make another gaussian which have region from -1 to 1 and used SetFillColor.
But I couldn’t.
Please help me.

3

The way to do it would be:

{
   TF1 *f=new TF1("f", "TMath::Gaus(x)", -6, 6);
   f->SetFillColor(3);
   f->SetFillStyle(1001);
   f->Draw();
}

But doing that the function is drawn as a histogram, with steps.
There is a work around. You can do:

   f->Draw("LF2");

I will apply a fix to draw the filled function that way by default.

1 Like
4

I made a PR for that. https://github.com/root-project/root/pull/5174
Thanks.

2 Likes
5

Thanks for suggesting my question as Pull requests!

If we fill the gaussian, it is clear to fill area from y=0 to from Gauss function.
If we can fill in between two functions area etc in the future, I think it looks useful.

I look forward to using renewal function!

6

Meanwhile you can use the workaround I sent you

Can you provide an example showing the area to be filled ?

7

The reason why I made this question starts from “drawing Gaussian more than σ region”.

So, I thought I use two function about x=σ and y=Cexp[x^2/2σ^2], then it may represent fmore than σ filled region.

8

Ok … a small script would help.