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source: git/external/TrackCovariance/TrkUtil.cc@ fd4b326

Last change on this file since fd4b326 was f9517a5, checked in by Pavel Demin <pavel.demin@…>, 4 years ago

include TMath.h to TrkUtil.cc
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File size: 5.2 KB
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[a617744]1#include "TrkUtil.h"
[f9517a5]2#include <TMath.h>
[df408d2]3#include <iostream>
[a617744]4
5// Constructor
6TrkUtil::TrkUtil(Double_t Bz)
7{
8 fBz = Bz;
9}
10TrkUtil::TrkUtil()
11{
12 fBz = 0.0;
13}
14//
15// Destructor
16TrkUtil::~TrkUtil()
17{
18 fBz = 0.0;
19}
20//
21// Helix parameters from position and momentum
22// static
23TVectorD TrkUtil::XPtoPar(TVector3 x, TVector3 p, Double_t Q, Double_t Bz)
24{
25 //
26 TVectorD Par(5);
27 // Transverse parameters
28 Double_t a = -Q * Bz * cSpeed(); // Units are Tesla, GeV and meters
29 Double_t pt = p.Pt();
30 Double_t C = a / (2 * pt); // Half curvature
31 //cout << "ObsTrk::XPtoPar: fB = " << fB << ", a = " << a << ", pt = " << pt << ", C = " << C << endl;
32 Double_t r2 = x.Perp2();
33 Double_t cross = x(0) * p(1) - x(1) * p(0);
[f9517a5]34 Double_t T = TMath::Sqrt(pt * pt - 2 * a * cross + a * a * r2);
35 Double_t phi0 = TMath::ATan2((p(1) - a * x(0)) / T, (p(0) + a * x(1)) / T); // Phi0
[a617744]36 Double_t D; // Impact parameter D
37 if (pt < 10.0) D = (T - pt) / a;
38 else D = (-2 * cross + a * r2) / (T + pt);
39 //
40 Par(0) = D; // Store D
41 Par(1) = phi0; // Store phi0
42 Par(2) = C; // Store C
43 //Longitudinal parameters
[f9517a5]44 Double_t B = C * TMath::Sqrt(TMath::Max(r2 - D * D, 0.0) / (1 + 2 * C * D));
45 Double_t st = TMath::ASin(B) / C;
[a617744]46 Double_t ct = p(2) / pt;
47 Double_t z0 = x(2) - ct * st;
48 //
49 Par(3) = z0; // Store z0
50 Par(4) = ct; // Store cot(theta)
51 //
52 return Par;
53}
54// non-static
55TVectorD TrkUtil::XPtoPar(TVector3 x, TVector3 p, Double_t Q)
56{
57 //
58 TVectorD Par(5);
59 Double_t Bz = fBz;
60 Par = XPtoPar(x, p, Q, Bz);
61 //
62 return Par;
63}
64//
65TVector3 TrkUtil::ParToX(TVectorD Par)
66{
67 Double_t D = Par(0);
68 Double_t phi0 = Par(1);
69 Double_t z0 = Par(3);
70 //
71 TVector3 Xval;
[f9517a5]72 Xval(0) = -D * TMath::Sin(phi0);
73 Xval(1) = D * TMath::Cos(phi0);
[a617744]74 Xval(2) = z0;
75 //
76 return Xval;
77}
78//
79TVector3 TrkUtil::ParToP(TVectorD Par)
[df408d2]80{
81 if (fBz == 0.0)
82std::cout << "TrkUtil::ParToP: Warning Bz not set" << std::endl;
83 //
84 return ParToP(Par,fBz);
85}
86//
87TVector3 TrkUtil::ParToP(TVectorD Par, Double_t Bz)
[a617744]88{
89 Double_t C = Par(2);
90 Double_t phi0 = Par(1);
91 Double_t ct = Par(4);
92 //
93 TVector3 Pval;
[df408d2]94 Double_t pt = Bz * cSpeed() / TMath::Abs(2 * C);
[f9517a5]95 Pval(0) = pt * TMath::Cos(phi0);
96 Pval(1) = pt * TMath::Sin(phi0);
[a617744]97 Pval(2) = pt * ct;
98 //
99 return Pval;
100}
101//
102Double_t TrkUtil::ParToQ(TVectorD Par)
103{
104 return TMath::Sign(1.0, -Par(2));
105}
106
107//
108// Parameter conversion to ACTS format
109TVectorD TrkUtil::ParToACTS(TVectorD Par)
110{
111 TVectorD pACTS(6); // Return vector
112 //
113 Double_t b = -cSpeed() * fBz / 2.;
114 pACTS(0) = 1000 * Par(0); // D from m to mm
[df408d2]115 pACTS(1) = 1000 * Par(3); // z0 from m to mm
[a617744]116 pACTS(2) = Par(1); // Phi0 is unchanged
[f9517a5]117 pACTS(3) = TMath::ATan2(1.0, Par(4)); // Theta in [0, pi] range
118 pACTS(4) = Par(2) / (b * TMath::Sqrt(1 + Par(4) * Par(4))); // q/p in GeV
[a617744]119 pACTS(5) = 0.0; // Time: currently undefined
120 //
121 return pACTS;
122}
123// Covariance conversion to ACTS format
124TMatrixDSym TrkUtil::CovToACTS(TVectorD Par, TMatrixDSym Cov)
125{
126 TMatrixDSym cACTS(6); cACTS.Zero();
127 Double_t b = -cSpeed() * fBz / 2.;
128 //
129 // Fill derivative matrix
130 TMatrixD A(5, 5); A.Zero();
131 Double_t ct = Par(4); // cot(theta)
132 Double_t C = Par(2); // half curvature
133 A(0, 0) = 1000.; // D-D conversion to mm
134 A(1, 2) = 1.0; // phi0-phi0
[f9517a5]135 A(2, 4) = 1.0 / (TMath::Sqrt(1.0 + ct * ct) * b); // q/p-C
[a617744]136 A(3, 1) = 1000.; // z0-z0 conversion to mm
137 A(4, 3) = -1.0 / (1.0 + ct * ct); // theta - cot(theta)
[f9517a5]138 A(4, 4) = -C * ct / (b * TMath::Power(1.0 + ct * ct, 3.0 / 2.0)); // q/p-cot(theta)
[a617744]139 //
140 TMatrixDSym Cv = Cov;
141 TMatrixD At(5, 5);
142 At.Transpose(A);
143 Cv.Similarity(At);
144 TMatrixDSub(cACTS, 0, 4, 0, 4) = Cv;
145 cACTS(5, 5) = 0.1; // Currently undefined: set to arbitrary value to avoid crashes
146 //
147 return cACTS;
148}
149//
150// Parameter conversion to ILC format
151TVectorD TrkUtil::ParToILC(TVectorD Par)
152{
153 TVectorD pILC(5); // Return vector
154 //
155 pILC(0) = Par(0) * 1.0e3; // d0 in mm
156 pILC(1) = Par(1); // phi0 is unchanged
157 pILC(2) = -2 * Par(2) * 1.0e-3; // w in mm^-1
158 pILC(3) = Par(3) * 1.0e3; // z0 in mm
159 pILC(4) = Par(4); // tan(lambda) = cot(theta)
160 //
161 return pILC;
162}
163// Covariance conversion to ILC format
164TMatrixDSym TrkUtil::CovToILC(TMatrixDSym Cov)
165{
166 TMatrixDSym cILC(5); cILC.Zero();
167 //
168 // Fill derivative matrix
169 TMatrixD A(5, 5); A.Zero();
170 //
171 A(0, 0) = 1.0e3; // D-d0 in mm
172 A(1, 1) = 1.0; // phi0-phi0
173 A(2, 2) = -2.0e-3; // w-C
174 A(3, 3) = 1.0e3; // z0-z0 conversion to mm
175 A(4, 4) = 1.0; // tan(lambda) - cot(theta)
176 //
177 TMatrixDSym Cv = Cov;
178 TMatrixD At(5, 5);
179 At.Transpose(A);
180 Cv.Similarity(At);
181 cILC = Cv;
182 //
183 return cILC;
184}
185//
186// Conversion from meters to mm
187TVectorD TrkUtil::ParToMm(TVectorD Par) // Parameter conversion
188{
189 TVectorD Pmm(5); // Return vector
190 //
191 Pmm(0) = Par(0) * 1.0e3; // d0 in mm
192 Pmm(1) = Par(1); // phi0 is unchanged
193 Pmm(2) = Par(2) * 1.0e-3; // C in mm^-1
194 Pmm(3) = Par(3) * 1.0e3; // z0 in mm
195 Pmm(4) = Par(4); // tan(lambda) = cot(theta) unchanged
196 //
197 return Pmm;
198}
199TMatrixDSym TrkUtil::CovToMm(TMatrixDSym Cov) // Covariance conversion
200{
201 TMatrixDSym Cmm(5); Cmm.Zero();
202 //
203 // Fill derivative matrix
204 TMatrixD A(5, 5); A.Zero();
205 //
206 A(0, 0) = 1.0e3; // D-d0 in mm
207 A(1, 1) = 1.0; // phi0-phi0
208 A(2, 2) = 1.0e-3; // C-C
209 A(3, 3) = 1.0e3; // z0-z0 conversion to mm
210 A(4, 4) = 1.0; // lambda - cot(theta)
211 //
212 TMatrixDSym Cv = Cov;
213 TMatrixD At(5, 5);
214 At.Transpose(A);
215 Cv.Similarity(At);
216 Cmm = Cv;
217 //
218 return Cmm;
[d3165fa]219}
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