 ROOT   Reference Guide
Searching...
No Matches
foam_kanwa.C
Go to the documentation of this file.
1/// \file
2/// \ingroup tutorial_FOAM
3/// \notebook -js
4/// This program can be execute from the command line as folows:
5///
6/// ~~~{.cpp}
7/// root -l foam_kanwa.C
8/// ~~~
9///
10/// \macro_code
11///
13
14#include "Riostream.h"
15#include "TFoam.h"
16#include "TCanvas.h"
17#include "TH2.h"
18#include "TMath.h"
19#include "TFoamIntegrand.h"
20#include "TRandom3.h"
21
22//_____________________________________________________________________________
24 return x*x;
25}
26//_____________________________________________________________________________
27Double_t Camel2(Int_t nDim, Double_t *Xarg){
28 // 2-dimensional distribution for Foam, normalized to one (within 1e-5)
29 Double_t x=Xarg;
30 Double_t y=Xarg;
31 Double_t GamSq= sqr(0.100e0);
32 Double_t Dist= 0;
33 Dist +=exp(-(sqr(x-1./3) +sqr(y-1./3))/GamSq)/GamSq/TMath::Pi();
34 Dist +=exp(-(sqr(x-2./3) +sqr(y-2./3))/GamSq)/GamSq/TMath::Pi();
35 return 0.5*Dist;
36}
37//_____________________________________________________________________________
38
39Int_t foam_kanwa(){
40 cout<<"--- kanwa started ---"<<endl;
41 TH2D *hst_xy = new TH2D("hst_xy" , "x-y plot", 50,0,1.0, 50,0,1.0);
42 Double_t MCvect; // 2-dim vector generated in the MC run
43 //
44 TRandom *PseRan = new TRandom3(); // Create random number generator
45 PseRan->SetSeed(4357);
46 TFoam *FoamX = new TFoam("FoamX"); // Create Simulator
47 FoamX->SetkDim(2); // No. of dimensions, obligatory!
48 FoamX->SetnCells(500); // Optionally No. of cells, default=2000
49 FoamX->SetRhoInt(Camel2); // Set 2-dim distribution, included below
50 FoamX->SetPseRan(PseRan); // Set random number generator
51 FoamX->Initialize(); // Initialize simulator, may take time...
52 //
53 // visualising generated distribution
54 TCanvas *cKanwa = new TCanvas("cKanwa","Canvas for plotting",600,600);
55 cKanwa->cd();
56 // From now on FoamX is ready to generate events
57 int nshow=5000;
58 for(long loop=0; loop<100000; loop++){
59 FoamX->MakeEvent(); // generate MC event
60 FoamX->GetMCvect( MCvect); // get generated vector (x,y)
61 Double_t x=MCvect;
62 Double_t y=MCvect;
63 if(loop<10) cout<<"(x,y) = ( "<< x <<", "<< y <<" )"<<endl;
64 hst_xy->Fill(x,y);
65 // live plot
66 if(loop == nshow){
67 nshow += 5000;
68 hst_xy->Draw("lego2");
69 cKanwa->Update();
70 }
71 }// loop
72 //
73 hst_xy->Draw("lego2"); // final plot
74 cKanwa->Update();
75 //
76 Double_t MCresult, MCerror;
77 FoamX->GetIntegMC( MCresult, MCerror); // get MC integral, should be one
78 cout << " MCresult= " << MCresult << " +- " << MCerror <<endl;
79 cout<<"--- kanwa ended ---"<<endl;
80
81 return 0;
82}
int Int_t
Definition RtypesCore.h:45
double Double_t
Definition RtypesCore.h:59
double exp(double)
The Canvas class.
Definition TCanvas.h:23
Definition TCanvas.cxx:708
void Update() override
Definition TCanvas.cxx:2504
TFoam is the main class of the multi-dimensional general purpose Monte Carlo event generator (integra...
Definition TFoam.h:21
virtual void GetMCvect(Double_t *)
User may get generated MC point/vector with help of this method.
Definition TFoam.cxx:1176
virtual void MakeEvent()
User method.
Definition TFoam.cxx:1126
virtual void Initialize()
Basic initialization of FOAM invoked by the user.
Definition TFoam.cxx:323
virtual void GetIntegMC(Double_t &, Double_t &)
User method.
Definition TFoam.cxx:1211
virtual void SetnCells(Long_t nCells)
Definition TFoam.h:116
virtual void SetRhoInt(Double_t(*fun)(Int_t, Double_t *))
User may use this method to set the distribution object as a global function pointer (and not as an i...
Definition TFoam.cxx:1033
virtual void SetPseRan(TRandom *PseRan)
Definition TFoam.h:112
virtual void SetkDim(Int_t kDim)
Definition TFoam.h:115
virtual void Draw(Option_t *option="")
Draw this histogram with options.
Definition TH1.cxx:3073
2-D histogram with a double per channel (see TH1 documentation)}
Definition TH2.h:292
Int_t Fill(Double_t)
Invalid Fill method.
Definition TH2.cxx:294
Random number generator class based on M.
Definition TRandom3.h:27
This is the base class for the ROOT Random number generators.
Definition TRandom.h:27
virtual void SetSeed(ULong_t seed=0)
Set the random generator seed.
Definition TRandom.cxx:608
Double_t y[n]
Definition legend1.C:17
Double_t x[n]
Definition legend1.C:17
double Dist(void *xp, void *yp)
VecExpr< UnaryOp< Sqr< T >, VecExpr< A, T, D >, T >, T, D > sqr(const VecExpr< A, T, D > &rhs)
constexpr Double_t Pi()
Definition TMath.h:37