Re: TMinuit

You have at least 3 C++ coding errors in your code. In the attachement see lines marked with //<-----

Rene Brun

On Sun, 29 Jan 2006,
Nevzat Guler wrote:

>
> Hello,
> I am having some problems with TMinuit. I took the example Ifit.C
> and modified it for myself and incorporated into my program.
> In my root program I am looping over events in a tree. Therefore I
> cannot send you a real working version of the program but
> I am sending the program itself. The ntuple is really big so I cannot send
> it. The program is below (also in attachment). In the attachment there is
> also a header file
> for it and the "output" of the program. Currently it does not work. MIGRAD
> fails to make improvement and I keep getting the following error message:
>
> Error: G__CallFunc::SetArgArray() must be initialized with
> 'G__CallFunc::SetFunc(G__ClassInfo* cls,char* fname,char* args,long*
> poffset)' first
>
> I don't know if this error is causing the program not to work or if the
> function that I am fitting is terribly bad.
>
> Thank you for your inputs.
>
>
> znevzat.C
>
> ==================================================================
> #define znevzat_cxx
> #include "TROOT.h"
> #include "TH2.h"
> #include "TStyle.h"
> #include "TCanvas.h"
> #include "TGraph.h"
> #include "TStopwatch.h"
> #include "TTree.h"
> #include "TFile.h"
> #include "TNtuple.h"
> #include "TChain.h"
> #include "TStyle.h"
> #include "TMath.h"
> #include "TFormula.h"
> #include "TH1.h"
> #include "TF1.h"
> gSystem->Load("libMinuit");
> #include "TMinuit.h"
>
> #include "znevzat.h"
> #include <TH2.h>
> #include <TStyle.h>
> #include <TCanvas.h>
>
> const Int_t ndata=20000;
> Double_t deltaPHI[ndata];
> Double_t deltaZ[ndata];
> Double_t errorDZ[ndata];
> Double_t deltaTHETA[ndata];
> Double_t sigmaDZ[300];
> Double_t thetabin[50];
> Double_t mombin[50];
> Double_t rad2deg=180.0/3.14159;
>
> //______________________________________________________________________________
> Double_t func(Double_t Df,Double_t *par)
> {
> Double_t value = (par[0]*Df+par[1]);
> return value;
> }
>
> //============================================================================================
> void fcn(Int_t &npar, Double_t *gin, Double_t &f, Double_t *par, Int_t
> iflag, Int_t ndata)
> {
> Int_t i;
>
> ////calculate chisquare
>
> Double_t chisq=0;
> Double_t chi;
> for(i=0;i<ndata;i++) {
> chi=(deltaZ[i]-func(deltaPHI[i],par));
> chisq+=chi*chi;
> }
> f = chisq;
> }
> //=============================================================================================
>
>
> void znevzat::Loop()
> {
> if (fChain == 0) return;
> Int_t nentries = Int_t(fChain->GetEntriesFast());
>
> //====================== DEFINE
> THINGS===============================================
> TH2D *hh = new TH2D("hh", "temporary histogram", 100, -1., 1.,100,-1.,1.);
>
> for(Int_t j=0;j<ndata;j++){
> deltaPHI[j]=deltaZ[j]=errorDZ[j]=deltaTHETA[j]=0.0;}
> //==============================================================================
>
> Int_t nbytes = 0, nb = 0;
> //for (Int_t jentry=0; jentry<nentries;jentry++) {
> for (Int_t jentry=0; jentry<ndata;jentry++) {
> //====================== FILL ARRAYS and HISTOGRAMS
> =============================
>
>
> if(npro==1&&abs(prz-gprz)<1.0&&abs(prf-gprf)<0.5&&abs(gprm-0.95)<0.1&&abs(57.*prt-35.)<10.){
> hh->Fill((prz-gprz)/prm,prf-gprf);
> // hh->Fill(gprt*rad2deg,gprm);
> }
>
> deltaPHI[jentry]=prf-gprf;
> deltaZ[jentry]=prz-gprz;
> deltaTHETA[jentry]=prt-gprt;
> errorDZ[jentry]=prz-rprz;
>
> //===============================================================================
> Int_t ientry = LoadTree(jentry);
> if (ientry < 0) break;
> nb = fChain->GetEntry(jentry); nbytes += nb;
> // if (Cut(ientry) < 0) continue;
> }
> //====================== ANALYZE RESULTS
> ========================================
>
>
> TCanvas *c1 = new TCanvas("c1","",0,0,600,400);
> gStyle->SetOptFit(0111);
> gPad->SetGrid();
>
> hh->Draw();
> TProfile *prof = hh->ProfileX();
> prof->SetLineColor(kRed);
> prof->Draw("same");
> prof->Draw("");
> prof->Fit("pol1","R","",-0.6.,0.6);
>
> TMinuit *gMinuit = new TMinuit(2);
> gMinuit->SetFCN(fcn);
>
> Double_t arglist[10];
> Int_t ierflg = 0;
> arglist[0] = 1;
> gMinuit->mnexcm("SET ERR", arglist ,1,ierflg);
>
> // Set starting values and step sizes for parameters
> static Double_t vstart[2] = {0.0 , 0.0};
> static Double_t step[2] = {0.0001 , 0.0001};
> gMinuit->mnparm(0, "a1", vstart[0], step[0], 0,0,ierflg);
> gMinuit->mnparm(1, "a2", vstart[1], step[1], 0,0,ierflg);
>
> // Now ready for minimization step
> arglist[0] = 100000000;
> arglist[1] = 0.001.;
> gMinuit->mnexcm("MIGRAD", arglist ,2,ierflg);
>
> // Print results
> Double_t amin,edm,errdef;
> Int_t nvpar,nparx,icstat;
> gMinuit->mnstat(amin,edm,errdef,nvpar,nparx,icstat);
> gMinuit->mnprin(3,amin);
> }
>
>
> ==================================================================