Re: TF3::GetHistogram() seg violation

From: Lorenzo Moneta <Lorenzo.Moneta_at_cern.ch>
Date: Wed, 30 Mar 2011 14:16:53 +0000

Hi Serhiy,

 Currently the TF3 is drawing in a different way (by showing the contours when f(x,y,z)=0)) and does not need to have the contained histogram filled with the values. Probably we will have to revise this and at some point we should put the code to fill the histogram inside the TF3

 Regards

 Lorenzo  

On Mar 30, 2011, at 3:38 PM, Serhiy Senyukov wrote:

> Hi Lorenzo,
> 
> Thank you for your answer.
> Indeed such a brute-force way should work.
> However, I do not understand why this operation cannot be done inside GetHistogram(). What is the meaning of this method as it is implemented now? Moreover its behavior is not coherent to the 1D and 2D cases.
> 
> Regards,
> Serhiy.
> 

>> -----Original Message-----
>> From: Lorenzo Moneta
>> Sent: Wednesday, March 30, 2011 3:26 PM
>> To: Serhiy Senyukov
>> Cc: Olivier Couet; roottalk (Mailing list discussing all aspects of the
>> ROOT system.)
>> Subject: Re: [ROOT] TF3::GetHistogram() seg violation
>>
>> Hi,
>>
>> To fill a 3D histogram from a TF3 function you can do something like
>> this
>>
>> {
>>
>>
>> TF3 * f3 = new TF3("f3","x*x+y*y+z");
>> f3->Draw();
>> gPad->Update(); // this forces the creation of the histogram
>> TH3 * h3=(TH3*) f3->GetHistogram();
>>
>> double xv[3];
>> f3->InitArgs(xv, f3->GetParameters());
>> for (int i=1;i<=h3->GetNbinsX();i++) {
>> xv[0] = h3->GetXaxis()->GetBinCenter(i);
>> for (int j=1;j<=h3->GetNbinsY();j++) {
>> xv[1] = h3->GetYaxis()->GetBinCenter(j);
>> for (int k=1;k<=h3->GetNbinsZ();k++) {
>> xv[2] = h3->GetZaxis()->GetBinCenter(k);
>> int bin = h3->GetBin(i,j,k);
>> h3->SetBinContent(bin,f3->EvalPar(xv,f3->GetParameters())
>> );
>> }
>> }
>> }
>>
>> h3->Draw("ISO");
>> }
>>
>>
>> Lorenzo
>>
>>
>> On Mar 30, 2011, at 2:58 PM, Serhiy Senyukov wrote:
>>

>>> Thank you for your suggestion Oliver. However it is not the thing I

>> would like to do.

>>> What I really need is to translate 3D function into reasonable

>> histogram. Final goal is to visualize the original 3D function.

>>> 
>>>> -----Original Message-----
>>>> From: Olivier Couet
>>>> Sent: Wednesday, March 30, 2011 2:44 PM
>>>> To: Serhiy Senyukov
>>>> Cc: Olivier Couet; roottalk (Mailing list discussing all aspects of

>> the

>>>> ROOT system.)
>>>> Subject: RE: [ROOT] TF3::GetHistogram() seg violation
>>>> 
>>>> 
>>>> 
>>>> I think the TH3 ib that case is only used to draw the frame and

>> remains

>>>> empty. You should try to do something like that:
>>>> 
>>>> {
>>>>   TH3D *earth = new TH3D("earth", "earth", 100, -1., 1., 100, -1.,
>>>> 1.,100, -1., 1.);
>>>>   double phi=0., cos_theta=0., theta=0.;
>>>>   for(int i=0; i<100; i++){
>>>>      phi=gRandom->Uniform(0., 6.28);
>>>>      cos_theta=gRandom->Uniform(0., 1.);
>>>>      theta=acos(cos_theta);
>>>>      earth->Fill(cos(phi)*sin(theta), sin(phi)*sin(theta),
>>>> cos_theta);
>>>>   }
>>>>   TCanvas *c1 = new TCanvas("c1", "c1",1);
>>>>      earth->SetMarkerStyle(4);
>>>> 
>>>>   earth->Draw("box");
>>>> }
>>>> 
>>>> 
>>>> 
>>>> Org:    CERN - European Laboratory for Particle Physics.
>>>> Mail:   1211 Geneve 23 - Switzerland                     Mailbox:
>>>> J25910
>>>> E-Mail: Olivier.Couet_at_cern.ch                            Phone:

>> +41

>>>> 22 7676522
>>>> WWW:    http://cern.ch/Olivier.Couet/                    Fax:

>> +41

>>>> 22 7670300
>>>> 
>>>> On Wed, 30 Mar 2011, Serhiy Senyukov wrote:
>>>> 
>>>>>> As you see I get 100 .
>>>>>> I am using the trunk
>>>>> [Serhiy Senyukov] As far as I can see from your code you are

>> getting

>>>> 100 evaluating the function itself. Contrary I get zero by asking

>> the

>>>> bin content of the histogram derived from the function.
>>>>> 
>>>>>>>> I do not see what you describe here.
>>>>>>> [Serhiy Senyukov] Ok. I have found the reason for the first

>> issue.

>>>>>> There
>>>>>>> were parameters missing in the declaration of the 3D function.
>>>> However
>>>>>>> the bin content of the produced histogram is always zero.
>>>>>>> 
>>>>>>> Regards,
>>>>>>> Serhiy.
>>>>>>> 
>>>>>>>> root [0] .x ser.C
>>>>>>>> Processing ser.C...
>>>>>>>> Test function3 test = 100
>>>>>>>> Info in <TCanvas::MakeDefCanvas>:  created default TCanvas with
>>>> name
>>>>>> c1
>>>>>>>> 
>>>>>>>> The macro is:
>>>>>>>> 
>>>>>>>> Double_t test(Double_t *x, Double_t *par)
>>>>>>>> {
>>>>>>>>    return 100;
>>>>>>>> }
>>>>>>>> 
>>>>>>>> void ser(Int_t nPoints=5){
>>>>>>>>   TF3* test_f3=new TF3("test_f3",test,0,10,0,10,0,10,2);
>>>>>>>>   test_f3->SetParameters(1,2);
>>>>>>>>   test_f3->SetNpx(nPoints);
>>>>>>>>   test_f3->SetNpy(nPoints);
>>>>>>>>   test_f3->SetNpz(nPoints);
>>>>>>>> 
>>>>>>>>   cout<<"Test function3 test = "<<test_f3->Eval(5,5,5)<<endl;
>>>>>>>> 
>>>>>>>>   test_f3->Draw();
>>>>>>>>   TH3F* test3_hist=(TH3F*)test_f3->GetHistogram();
>>>>>>>> }
>>>>> 
>>>>> 
>>> 
> 

Received on Wed Mar 30 2011 - 16:16:59 CEST