Hi everyone,
Sorry I have to ask this question which may seems basic to you.
My question concern the histograms! So, I know there is TH1,TH2,TH3
1/
But if I would like to add a signal into an histogram (for example (t,y) ) then, should I use :
-TH1 : hisot->Fill(t,y) (FFT.C example)
-TH2 :histo->Fill(t,y)
Ps:My signal is not a math expression to evaluate, but a set of data points I read from an ASCII file.
I think that the 2 solutions are right, but if so! what’s the difference then between TH2 and TH1 
2/
When I create a TH2D histogram, with:
for(expression)
{
for(i=0,i<N;i++)
{
histo->fill(index,t[i],y[i]);
}
index++;
}
I’m using this solution when I have millions of data lines in y, so I take sub signals of y with the length N.
What should then number of xbins and ybins at that case?
Thank you in advance! 