newly added. Not for productive used yetsvn diff | grep Index:

src/tests/rootMinuit2Test/minuit2test.C

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+/*******************************************************************
+  minuit2test.C
+
+  author: Andreas Suter
+  e-mail: andreas.suter@psi.ch
+
+  $Id$
+********************************************************************/
+
+#include <iostream>
+
+#include <TF1.h>
+#include <TH1.h>
+#include <TVirtualFitter.h>
+#include <TCanvas.h>
+#include <TMath.h>
+
+const double gGammaMu = TMath::TwoPi()*0.01355;
+const double gTauMu   = 2.19705; // in (us)
+
+TF1 *gFitFcn;
+
+//------------------------------------------------------------------
+/**
+ * <p>Background (flat for the moment)
+ *
+ * \param x 
+ * \param par par[0] is the background
+ */
+Double_t Background(Double_t *x, Double_t *par)
+{
+  return par[0];
+}
+
+//------------------------------------------------------------------
+/**
+ * <p>Asymmetry
+ *
+ * \param x
+ * \param par par[0] = asymmetry
+ *            par[1] = lambda
+ *            par[2] = B
+ *            par[3] = phase
+ */
+Double_t Asymmetry(Double_t *x, Double_t *par)
+{
+  return par[0]*TMath::Exp(-par[1]*x[0])*TMath::Cos(gGammaMu*par[2]*x[0]+par[3]/180.0*TMath::Pi());
+}
+
+//------------------------------------------------------------------
+/**
+ * <p>Spectrum
+ *
+ * \param x 
+ * \param par 
+ */
+Double_t Spectrum(Double_t *x, Double_t *par)
+{
+  return par[0]*TMath::Exp(-x[0]/gTauMu)*(1.0 + Asymmetry(x,&par[1])) + Background(x,&par[5]);
+}
+
+//------------------------------------------------------------------
+/**
+ * <p>minuit2test
+ *
+ * \param x 
+ * \param par 
+ */
+void minuit2test()
+{
+  TH1::AddDirectory(kFALSE);
+  TCanvas *c1 = new TCanvas("c1","Fitting Test",10,10,500,500);
+
+  // create a TF1 with the range from 0.0 to 12.0 and 6 parameters
+  gFitFcn = new TF1("gFitFcn", Spectrum, 0.0, 12.0, 6);
+  gFitFcn->SetNpx(1200);
+
+  // set parameters
+  gFitFcn->SetParNames("N0", "asym", "lambda", "B", "phase", "Bkg");
+  gFitFcn->SetParameter(0, 30.0);   // N0
+//  gFitFcn->SetParLimits(0, 0.0, 1.0e6);
+  gFitFcn->SetParameter(1, 0.11);    // asym
+//  gFitFcn->SetParLimits(1, 0.0, 0.33);
+  gFitFcn->SetParameter(2, 0.3);     // lambda
+//  gFitFcn->SetParLimits(2, 0.0, 100.0);
+  gFitFcn->SetParameter(3, 100.0);   // B
+//  gFitFcn->SetParLimits(3, 0.0, 1000.0);
+  gFitFcn->SetParameter(4, 0.0);     // phase
+//  gFitFcn->SetParLimits(4, -90.0, 90.0);
+  gFitFcn->SetParameter(5, 5.0);    // Bkg
+//  gFitFcn->SetParLimits(5, 0.0, 1000.0);
+
+  cout << endl << "gFitFcn->Integral(0.0, 12.0) = " << gFitFcn->Integral(0.0, 12.0);
+  cout << endl;
+
+  // fill histo
+  TH1F *histo = new TH1F("histo","Minuit2 Test",1200,0.0,12.0);
+  histo->FillRandom("gFitFcn", 100*(int)gFitFcn->Integral(0.0, 12.0));
+  histo->Rebin(5);
+
+  histo->Draw();
+
+  TVirtualFitter::SetDefaultFitter("Minuit2");
+  histo->Fit("gFitFcn", "LE"); // L->likleyhood, E->minos 
+}