Re: Problem with automatic range for histos

 Hi Kostas,

On 08/02/12 14:33, Konstantinos Karakostas wrote:
> Hi,
>
> TH1D *hped = new TH1D("hped","hped",500,0.,0.); =
> use 500 bins to range 0. up to 0. !!!!!

When xmin = xmax = 0.

0 is not the real value for the range edges. This is a special behaviour that allow the histogram to take an adequate range depending on the values of the entries.

Cheers,

        Vito

>
>
> Cheers,
> Kostas
>
>
> On 02/07/2012 07:15 PM, Vito Di Benedetto wrote:

>>   Dear ROOT experts,
>>
>> I'm trying to fit an histogram that I define with automatic range
>>
>>   TH1D *hped = new TH1D("hped","hped",500,0.,0.);
>>
>> if I fill it with only 500 entries, when I try to fit it, it seems to be
>> empty. I get the error message:
>>
>> Warning in <ROOT::Fit::FillData>: fit range is outside histogram range,
>> no fit data for xaxis
>> Warning in <Fit>: Fit data is empty
>>
>>
>> If I fill an identical histogram with 5000 entries the fit works fine.
>>
>> How can I avoid the problem in the case I have only 500 or less entries
>> in my histogram?
>>
>> In attach there is a macro reproducing this issue.
>> I'm using ROOT v5.32.00 on 32 bit GNU/Linux
>>
>> Cheers,
>> 	Vito
>>