Filling Histogram with Gauss distribution

[Arnab7]

Hi,
I want to fill a histogram with a Gaussian distribution with known mean value (most likely x$_c$ is 0) and sigma.
How can do that?

Secondly, I want to use the values of y for various x values.
Is it possible access that also for further calculation.

Regards,
A

[eguiraud]

Hi Arnab,
one way to do it:

TH1D h("h", "h", /*nbins=*/100, /*xmin=*/-3, /*xmax=*/3);
h.FillRandom("gaus", /*nsamples=*/5000);

You can access the bin content of a histogram with h.GetBinContent(nbin).

Hope this helps,
Enrico

[Arnab7]

Hi Enrico,
Thanks for your kind help.
One more thing is I was trying something like:

        TRandom3 rndgen;
         h.Fill(rndgen.Gaus(0.0,10));
         
     But I don't get any Gaussian distribution, instead, I get a line.
     Do you have any idea to fix it?

Thanks,
A

[eguiraud]

Hi,
from just that snippet I can’t be sure exactly what you are doing wrong, but this works:

TH1D h("h", "h", 100, -3., 3.);
TRandom3 rndgen;
for (int i = 0; i < 100; ++i) h.Fill(rndgen.Gaus(0.,1.));
h2.Draw();

[Arnab7]

@eguiraud

for (int i = 0; i < 100; ++i)

Hi,
Now it works.
Thank you very much.