Rene,
yes, itmust. So why is the binning not automatically taken over?
Thomas.
Rene Brun wrote:
> Thomas,
>
> The resulting histogram must have the same number of bins than the
> operand histograms.
>
> Rene Brun
>
> On Thu, 18 Mar 2004, Thomas Bretz wrote:
>
>
>>Hi Rene,
>>
>>why does h4 need the same number of bins? It is enough if h4 'takes' the
>>binning from either h3 or h2, isn't it?
>>
>>Thomas.
>>
>>Rene Brun wrote:
>>
>>>Your two projections h2 and h3 have the same number of bins,
>>>eg you can do h3->Divide(h2);
>>>However, you call the default constructor for h4. h4 does not have the
>>>same number of bins as h2 and h3.
>>>Instead of
>>> TH2D *h4 = new TH2D;
>>> h4->Divide(h3, h2);
>>>do
>>> TH2D *h4 = (TH2D*)h2->Clone();
>>> h4->Divide(h3, h2);
>>>
>>>Rene Brun
>>>
>>>Thomas Bretz wrote:
>>>
>>>
>>>>Hi,
>>>>
>>>>I have a
>>>>Double_t x[5] = { 0, 1, 2, 3, 4 };
>>>>TH3D fHist("", "", 4, x, 4, x, 4, x);
>>>>and do:
>>>>fHist.GetZaxis()->SetRange(3, 4);
>>>>TH1 *h2 = fHist.Project3D("xy_off"); //, -1, 9999, "E");
>>>>
>>>>fHist.GetZaxis()->SetRange(1,2);
>>>>TH1 *h3 = fHist.Project3D("xy_on"); //, -1, 9999, "E");
>>>>
>>>>TH2D *h4 = new TH2D;
>>>>h4->Divide(h3, h2);
>>>>
>>>>And I get
>>>>Attempt to divide histograms with different number of bins...
>>>>
>>>>What am I doing wrong? I would expect to have two projections to have
>>>>the same binning...
>>>>
>>>>Thomas.
>>>
>>>
>
>
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