Obtaining an envelope curve

ROOT
1

Hi,

Is there a straightforward way for performing a fit in order to get the envelope of a distribution?

I’m specifically thinking of a Gaussian envelope on a TH1, so not really sophisticated.

Thanks,
Eleni

PS: For good measure, I’m also posting the same question to RooFit.

2

Hi,

What do you mean the “envelope of a distribution” ?

If you want to get the parameter of a distribution from an histogram, just do for example (“gaussian case”):

h1->Fit(“gaus”)

Lorenzo

3

Maybe I should have written “the envelope of the data”.

Here is a naive example of an envelope curve from google:

Please note that my data is not as fluctuating or as harmonic as in this example, so it’s not about decomposition etc. I just wonder if I can obtain a Gaussian which will encompass my histogram. (Simple fitting does not do this job.)

Regards,
Eleni

4

Hi,

We don;t have then such feature in ROOT. You would need to build something yourself wch create for example another histogram or graph with data points summarizing your data
and then you can fit those with ROOT

Cheers

Lorenzo

5

Thanks for the answer! It saves me from further searching, also it’s a nice idea to “summarize” with some of the points and see what happens with a fit.

Thanks,
Eleni

6

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