Variable bin size

ROOT
1

I have boon looking though the root docs and saw that TH1 and friends support variable bin size. What I could not find is how these variable bin sizes are determined. Can anybody give me a hand with this?

2

Use the specialized constructors in TH1, TH2, TH3 where you can define
an array of bin low-edges. For example with TH1F:

TH1F(const char *name,const char *title,Int_t nbinsx,Axis_t xlow,Axis_t xup); TH1F(const char *name,const char *title,Int_t nbinsx,const Float_t *xbins); TH1F(const char *name,const char *title,Int_t nbinsx,const Double_t *xbins);

Using one of last two constructors, you specify an array xbins of nbinsx+1 values

Rene

3

I see, so, root does not calculate the optimum bin width for you, you have to do that another way and then rebin on the fly.

4

ROOT calculates the origine and bin size automatically when analyzing Trees via TTree::Draw, but still with equal bin sizes.

Rene