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source: git/external/TrackCovariance/ObsTrk.cc@ a63afb1

Last change on this file since a63afb1 was a0f5d71, checked in by Michele Selvaggi <michele.selvaggi@…>, 4 years ago

added latest version of ObsTrk class
  • Property mode set to 100644
File size: 6.8 KB
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1#include <TMath.h>
2#include <TVector3.h>
3#include <TMatrixD.h>
4#include <TMatrixDSym.h>
5#include <TDecompChol.h>
6#include <TRandom.h>
7#include <iostream>
8#include "SolGridCov.h"
9#include "ObsTrk.h"
10//
11// Constructors
12// x(3) track origin, p(3) track momentum at origin, Q charge, B magnetic field in Tesla
13ObsTrk::ObsTrk(TVector3 x, TVector3 p, Double_t Q, Double_t B, SolGridCov *GC)
14{
15 fGC = GC;
16 fGenX = x;
17 fGenP = p;
18 fGenQ = Q;
19 fB = B;
20 fGenPar.ResizeTo(5);
21 fGenParACTS.ResizeTo(6);
22 fGenParILC.ResizeTo(5);
23 fObsPar.ResizeTo(5);
24 fObsParACTS.ResizeTo(6);
25 fObsParILC.ResizeTo(5);
26 fCov.ResizeTo(5, 5);
27 fCovACTS.ResizeTo(6, 6);
28 fCovILC.ResizeTo(5, 5);
29 fGenPar = XPtoPar(x,p,Q);
30 fGenParACTS = ParToACTS(fGenPar);
31 fGenParILC = ParToILC(fGenPar);
32 /*
33 std::cout << "ObsTrk::ObsTrk: fGenPar";
34 for (Int_t i = 0; i < 5; i++)std::cout << fGenPar(i) << ", ";
35 std::cout << std::endl;
36 */
37 fObsPar = GenToObsPar(fGenPar, fGC);
38 fObsParACTS = ParToACTS(fObsPar);
39 fObsParILC = ParToILC(fObsPar);
40 fObsX = ParToX(fObsPar);
41 fObsP = ParToP(fObsPar);
42 fObsQ = ParToQ(fObsPar);
43 fCovACTS = CovToACTS(fCov);
44 fCovILC = CovToILC(fCov);
45}
46//
47// Destructor
48ObsTrk::~ObsTrk()
49{
50 fGenX.Clear();
51 fGenP.Clear();
52 fGenPar.Clear();
53 fGenParACTS.Clear();
54 fObsX.Clear();
55 fObsP.Clear();
56 fObsPar.Clear();
57 fObsParACTS.Clear();
58 fCov.Clear();
59 fCovACTS.Clear();
60}
61TVectorD ObsTrk::XPtoPar(TVector3 x, TVector3 p, Double_t Q)
62{
63 //
64 TVectorD Par(5);
65 // Transverse parameters
66 Double_t a = -Q*fB*0.2998; // Units are Tesla, GeV and meters
67 Double_t pt = p.Pt();
68 Double_t C = a / (2 * pt); // Half curvature
69 //std::cout << "ObsTrk::XPtoPar: fB = " << fB << ", a = " << a << ", pt = " << pt << ", C = " << C << std::endl;
70 Double_t r2 = x.Perp2();
71 Double_t cross = x(0)*p(1) - x(1)*p(0);
72 Double_t T = TMath::Sqrt(pt*pt - 2 * a*cross + a*a*r2);
73 Double_t phi0 = TMath::ATan2((p(1) - a*x(0)) / T, (p(0) + a*x(1)) / T); // Phi0
74 Double_t D; // Impact parameter D
75 if (pt < 10.0) D = (T - pt) / a;
76 else D = (-2 * cross + a*r2) / (T + pt);
77 //
78 Par(0) = D; // Store D
79 Par(1) = phi0; // Store phi0
80 Par(2) = C; // Store C
81 //Longitudinal parameters
82 Double_t B = C*TMath::Sqrt(TMath::Max(r2 - D*D,0.0) / (1 + 2 * C*D));
83 Double_t st = TMath::ASin(B) / C;
84 Double_t ct = p(2) / pt;
85 Double_t z0 = x(2) - ct*st;
86 //
87 Par(3) = z0; // Store z0
88 Par(4) = ct; // Store cot(theta)
89 //
90 return Par;
91}
92//
93TVector3 ObsTrk::ParToX(TVectorD Par)
94{
95 Double_t D = Par(0);
96 Double_t phi0 = Par(1);
97 Double_t z0 = Par(3);
98 //
99 TVector3 Xval;
100 Xval(0) = -D*TMath::Sin(phi0);
101 Xval(1) = D*TMath::Cos(phi0);
102 Xval(2) = z0;
103 //
104 return Xval;
105}
106//
107TVector3 ObsTrk::ParToP(TVectorD Par)
108{
109 Double_t C = Par(2);
110 Double_t phi0 = Par(1);
111 Double_t ct = Par(4);
112 //
113 TVector3 Pval;
114 Double_t pt = fB*0.2998 / TMath::Abs(2 * C);
115 Pval(0) = pt*TMath::Cos(phi0);
116 Pval(1) = pt*TMath::Sin(phi0);
117 Pval(2) = pt*ct;
118 //
119 return Pval;
120}
121//
122
123Double_t ObsTrk::ParToQ(TVectorD Par)
124{
125 return TMath::Sign(1.0, -Par(2));
126}
127//
128TVectorD ObsTrk::GenToObsPar(TVectorD gPar, SolGridCov *GC)
129{
130 TVector3 p = ParToP(gPar);
131 Double_t pt = p.Pt();
132 Double_t tanTh = 1.0 / TMath::Abs(gPar(4));
133 Double_t angd = TMath::ATan(tanTh)*180. / TMath::Pi();
134 //
135 // Check ranges
136 Double_t minPt = GC->GetMinPt ();
137 if (pt < minPt) std::cout << "Warning ObsTrk::GenToObsPar: pt " << pt << " is below grid range of " << minPt << std::endl;
138 Double_t maxPt = GC->GetMaxPt();
139 if (pt > maxPt) std::cout << "Warning ObsTrk::GenToObsPar: pt " << pt << " is above grid range of " << maxPt << std::endl;
140 Double_t minAn = GC->GetMinAng();
141 if (angd < minAn) std::cout << "Warning ObsTrk::GenToObsPar: angle " << angd
142 << " is below grid range of " << minAn << std::endl;
143 Double_t maxAn = GC->GetMaxAng();
144 if (angd > maxAn) std::cout << "Warning ObsTrk::GenToObsPar: angle " << angd
145 << " is above grid range of " << maxAn << std::endl;
146 //
147 TMatrixDSym Cov = GC->GetCov(pt, angd);
148 fCov = Cov;
149 //
150 // Now do Choleski decomposition and random number extraction, with appropriate stabilization
151 //
152 TMatrixDSym CvN = Cov;
153 TMatrixDSym DCv(5); DCv.Zero();
154 TMatrixDSym DCvInv(5); DCvInv.Zero();
155 for (Int_t id = 0; id < 5; id++)
156 {
157 Double_t dVal = TMath::Sqrt(Cov(id, id));
158 DCv (id, id) = dVal;
159 DCvInv(id, id) = 1.0 / dVal;
160 }
161 CvN.Similarity(DCvInv); // Normalize diagonal to 1
162 TDecompChol Chl(CvN);
163 Bool_t OK = Chl.Decompose(); // Choleski decomposition of normalized matrix
164 TMatrixD U = Chl.GetU(); // Get Upper triangular matrix
165 TMatrixD Ut(TMatrixD::kTransposed, U); // Transposed of U (lower triangular)
166 TVectorD r(5);
167 for (Int_t i = 0; i < 5; i++)r(i) = gRandom->Gaus(0.0, 1.0); // Array of normal random numbers
168 TVectorD oPar = gPar + DCv*(Ut*r); // Observed parameter vector
169 //
170 return oPar;
171}
172// Parameter conversion to ACTS format
173TVectorD ObsTrk::ParToACTS(TVectorD Par)
174{
175 TVectorD pACTS(6); // Return vector
176 //
177 Double_t b = -0.29988*fB / 2.;
178 pACTS(0) = 1000*Par(0); // D from m to mm
179 pACTS(1) = 1000 * Par(3); // z0 from m to mm
180 pACTS(2) = Par(1); // Phi0 is unchanged
181 pACTS(3) = TMath::ATan(1.0 / Par(4)) + TMath::PiOver2(); // Theta in [0, pi] range
182 pACTS(4) = Par(2) / (b*TMath::Sqrt(1 + Par(4)*Par(4))); // q/p in GeV
183 pACTS(5) = 0.0; // Time: currently undefined
184 //
185 return pACTS;
186}
187// Covariance conversion to ACTS format
188TMatrixDSym ObsTrk::CovToACTS(TMatrixDSym Cov)
189{
190 TMatrixDSym cACTS(6); cACTS.Zero();
191 Double_t b = -0.29988*fB / 2.;
192 //
193 // Fill derivative matrix
194 TMatrixD A(5, 5); A.Zero();
195 Double_t ct = fGenPar(4); // cot(theta)
196 Double_t C = fGenPar(2); // half curvature
197 A(0, 0) = 1000.; // D-D conversion to mm
198 A(1, 2) = 1.0; // phi0-phi0
199 A(2, 4) = 1.0/(TMath::Sqrt(1.0 + ct*ct) * b); // q/p-C
200 A(3, 1) = 1000.; // z0-z0 conversion to mm
201 A(4, 3) = -1.0 / (1.0 + ct*ct); // theta - cot(theta)
202 A(4, 4) = -C*ct / (b*pow(1.0 + ct*ct,3.0/2.0)); // q/p-cot(theta)
203 //
204 TMatrixDSym Cv = Cov;
205 TMatrixD At(5, 5);
206 At.Transpose(A);
207 Cv.Similarity(At);
208 TMatrixDSub(cACTS, 0, 4, 0, 4) = Cv;
209 cACTS(5, 5) = 0.1; // Currently undefined: set to arbitrary value to avoid crashes
210 //
211 return cACTS;
212}
213
214// Parameter conversion to ILC format
215TVectorD ObsTrk::ParToILC(TVectorD Par)
216{
217 TVectorD pILC(5); // Return vector
218 //
219 pILC(0) = Par(0)*1.0e3; // d0 in mm
220 pILC(1) = Par(1); // phi0 is unchanged
221 pILC(2) = -2 * Par(2)*1.0e-3; // w in mm^-1
222 pILC(3) = Par(3)*1.0e3; // z0 in mm
223 pILC(4) = Par(4); // tan(lambda) = cot(theta)
224 //
225 return pILC;
226}
227// Covariance conversion to ILC format
228TMatrixDSym ObsTrk::CovToILC(TMatrixDSym Cov)
229{
230 TMatrixDSym cILC(5); cILC.Zero();
231 //
232 // Fill derivative matrix
233 TMatrixD A(5, 5); A.Zero();
234 //
235 A(0, 0) = 1.0e3; // D-d0 in mm
236 A(1, 1) = 1.0; // phi0-phi0
237 A(2, 2) = -2.0e-3; // w-C
238 A(3, 3) = 1.0e3; // z0-z0 conversion to mm
239 A(4, 4) = 1.0; // tan(lambda) - cot(theta)
240 //
241 TMatrixDSym Cv = Cov;
242 TMatrixD At(5, 5);
243 At.Transpose(A);
244 Cv.Similarity(At);
245 cILC = Cv;
246 //
247 return cILC;
248}
249
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