Divide a histogram with a number

ROOT
1

I am trying to create a histogram that contains the mean pulse of various pulses. I am easily able to create the total pulses and add them all in a histogram. When I come to divide the histogram, that contains the total pulses, with the number of pulses using

TH1F hmean = 8*htotal; hmean->Draw();
I get an error

Then I tried using

TH1F hmean = 8*(*htotal); hmean->Draw();
and I got

and an empty canvas so, I tried

TH1F hmean = 8*htotal; hmean.Draw();
and I got

and an empty canvas.

Note that I am running root on lxplus. Is there a way around it?

1 Like
2

The TH1F class does not have the “operator*” method defined at all.
There exist various Add, Divide, Multiply and Scale methods: see the TH1 class description.

3

I tried to use Divide but I don’t know how. I first, created a function that has only the value 1 and then I will try to divide it like this

TF1 *constant = new TF1("constant","1",0,channels); TH1F hmean = htotal->Divide("constant",1.); hmean->Draw();

but i get an error that something must be wrong with TF1 or TH1F, with the arguments of Divide() that is. Any idea on that?

4

And which one of the three available TH1::Divide methods returns a histogram?
(A small hint: as far as I can see they all return a Bool_t.)

5

That is true!
But how am I going to create the histogram?

6

A really very tough question, indeed. :-k
:bulb: Maybe you could find some magic Clone method? :mrgreen:
And maybe this magic Clone method would allow you to change the name of the histogram, too? :-k
And then maybe you could simply Scale this newly created histogram by 8? <img src="/uploads/default/original/2X/8/84c2fe9464a4066c00e1bd5978e913e7869cbb07.gif" width=“22” height=“16” alt=":-"" title=“Whistle”/>
I really don’t know what the best approach in your case is. O:)

7

Thank you very much for your help!
It really worked!
Kind regards!
Cheers!!!

8

I have also tried in macro…but it showing error