RE: TF3::GetHistogram() seg violation

Hi Lorenzo,

Thank you for the explanation. Now I see how it works. I found the correct way to visualize my function without going to histograms. Actually what I needed was the equipotential surface.

Thank you all for the fruitful discussion. Regards,
Serhiy.

> -----Original Message-----
> From: Lorenzo Moneta
> Sent: Wednesday, March 30, 2011 4:17 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 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 - 16:50:39 CEST