1 /**************************************************************************
2 * Copyright(c) 2001-2002, ALICE Experiment at CERN, All rights reserved. *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
7 * Permission to use, copy, modify and distribute this software and its *
8 * documentation strictly for non-commercial purposes is hereby granted *
9 * without fee, provided that the above copyright notice appears in all *
10 * copies and that both the copyright notice and this permission notice *
11 * appear in the supporting documentation. The authors make no claims *
12 * about the suitability of this software for any purpose. It is *
13 * provided "as is" without express or implied warranty. *
14 **************************************************************************/
18 ////////////////////////////////////////////////////////////////////////
19 // Class used to generate correlated gaussian numbers with mean
20 // zero and known covariance matrix.
21 // Adapted from the Fortran code in Cernlib V122 (corset, corgen)
22 // F. James, Monte Carlo theory and practice,
23 // Rep. Prog. Phys. 43 (1980) 1145-1189.
24 // M.Masera 15.03.2001 9:30 - modified on 26.02.2002 17:40
25 ////////////////////////////////////////////////////////////////////////
27 #include <Riostream.h>
31 #include "AliGausCorr.h"
35 //_______________________________________________________________________
36 AliGausCorr::AliGausCorr():
41 // Default constructor
45 //_______________________________________________________________________
46 AliGausCorr::AliGausCorr(const TMatrixD & vec, Int_t size):
48 fCv(new TMatrixD(fSize,fSize))
51 // Standard constructor
53 for(Int_t j=0;j<fSize;j++){
55 for(Int_t k=0;k<j;k++){
56 accum += (*fCv)(j,k)* (*fCv)(j,k);
58 (*fCv)(j,j)=TMath::Sqrt(TMath::Abs(vec(j,j)-accum));
59 for(Int_t i=j+1;i<fSize;i++){
61 for(Int_t k=0;k<j;k++){
62 accum+=(*fCv)(i,k)* (*fCv)(j,k);
64 (*fCv)(i,j) = (vec(i,j)-accum) / (*fCv)(j,j);
69 //_______________________________________________________________________
70 AliGausCorr::AliGausCorr(const AliGausCorr & tgcorr):
73 fCv(new TMatrixD(fSize,fSize))
78 for(Int_t i=0;i<fSize;i++){
79 for(Int_t j=0;j<fSize;j++)(*fCv)(i,j)=(*tgcorr.fCv)(i,j);
83 //_______________________________________________________________________
84 AliGausCorr::~AliGausCorr()
90 //_______________________________________________________________________
91 void AliGausCorr::GetGaussN(TArrayD &vec) const
93 // return fSize correlated gaussian numbers
97 for(Int_t i=0; i<fSize; i++){
104 tmpv[i] = TMath::Sin(x)*TMath::Sqrt(-2*TMath::Log(y));
107 for(Int_t i=0;i<fSize;i++){
109 for(Int_t j=0;j<=i;j++)vec[i] += (*fCv)(i,j)* tmpv[j];
114 //_______________________________________________________________________
115 void AliGausCorr::PrintCv() const
117 // Printout of the "square root" cov. matrix
118 printf("\n AliGausCorr - triangular matrix \n");
119 for(Int_t i=0; i<fSize;i++){
120 for(Int_t j=0;j<(fSize-1);j++){
122 printf("| %12.4f ",(*fCv)(i,j));
125 printf(" %12.4f ",(*fCv)(i,j));
128 printf(" %12.4f | \n",(*fCv)(i,fSize-1));
133 //_______________________________________________________________________
134 AliGausCorr & AliGausCorr::operator=(const AliGausCorr & tgcorr)
136 // Assignment operator
137 if(&tgcorr != this && tgcorr.fSize!=fSize){
139 fSize = tgcorr.fSize;
140 fCv = new TMatrixD(fSize,fSize);
143 for(Int_t i=0;i<fSize;i++){
144 for(Int_t j=0;j<fSize;j++)(*fCv)(i,j)=(*tgcorr.fCv)(i,j);