Added methods for finding a given module in the DDL map (F. Prino)
[u/mrichter/AliRoot.git] / STEER / AliTrackFitterKalman.cxx
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9c4c8863 1/**************************************************************************
2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
3 * *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
6 * *
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 **************************************************************************/
15
16///////////////////////////////////////////////////////////////////////////////
17//
18// Kalman-Filter-like fit
19// to a straight-line crossing a set of arbitrarily oriented planes.
20// The resulting line is given by the equation:
21// (x-x0)/vx = (y-y0)/1 = (z-z0)/vz
22// Parameters of the fit are:
23// x0,y0,z0 (a point on the line) and
24// vx,1,vz (a vector collinear with the line)
25//
26// LIMITATION: The line must not be perpendicular to the Y axis.
27//
28// Origin: Iouri Belikov, CERN, Jouri.Belikov@cern.ch
29//
30//////////////////////////////////////////////////////////////////////////////
31
32#include <TMatrixD.h>
33#include <TMatrixDSym.h>
34
b7a98e0a 35#include "AliLog.h"
9c4c8863 36#include "AliTrackFitterKalman.h"
37
38ClassImp(AliTrackFitterKalman)
39
40const Double_t AliTrackFitterKalman::fgkMaxChi2=33.;
41
42AliTrackFitterKalman::
43AliTrackFitterKalman(AliTrackPointArray *array, Bool_t owner):
44 AliTrackFitter(array,owner),
57c8a1c2 45 fMaxChi2(fgkMaxChi2),
46 fSeed(kFALSE)
9c4c8863 47{
48 //
49 // Constructor
50 //
51}
52
57c8a1c2 53Bool_t AliTrackFitterKalman::Begin(Int_t first, Int_t last) {
54 //
55 // Make a seed out of the track points with the indices "first" and "last".
56 // This is the "default" seed.
57 //
58 if (fSeed) return kTRUE;
bead9796 59 fPoints->Sort();
57c8a1c2 60 AliTrackPoint fp,lp;
61 fPoints->GetPoint(fp,first); fPoints->GetPoint(lp,last);
62 return MakeSeed(&fp,&lp);
63}
64
65
66Bool_t AliTrackFitterKalman::
9c4c8863 67MakeSeed(const AliTrackPoint *p0, const AliTrackPoint *p1) {
68 //
69 // Make a seed out of the two track points
70 //
71 Double_t x0=p0->GetX(), y0=p0->GetY(), z0=p0->GetZ();
72 Double_t dx=p1->GetX()-x0, dy=p1->GetY()-y0, dz=p1->GetZ()-z0;
b7a98e0a 73 if (dy==0.) {
74 AliError("Seeds perpendicular to Y axis are not allowed !");
75 return kFALSE;
76 }
9c4c8863 77 Double_t vx=dx/dy;
78 Double_t vz=dz/dy;
79 Double_t par[5]={x0,y0,z0,vx,vz};
80
81 const Float_t *cv0=p0->GetCov();
82 const Float_t *cv1=p1->GetCov();
9c4c8863 83 Double_t rdy2=(cv0[3]+cv1[3])/dy/dy;
b7a98e0a 84 Double_t svx2=(cv0[0]+cv1[0])/dy/dy + vx*vx*rdy2;
85 Double_t svz2=(cv0[5]+cv1[5])/dy/dy + vz*vz*rdy2;
9c4c8863 86 Double_t cov[15]={
87 cv0[0],
88 cv0[1],cv0[3],
89 cv0[2],cv0[4],cv0[5],
90 0.,0.,0.,svx2,
91 0.,0.,0.,0.,svz2
92 };
93
94 SetSeed(par,cov);
57c8a1c2 95
96 return kTRUE;
9c4c8863 97}
98
99Bool_t AliTrackFitterKalman::AddPoint(const AliTrackPoint *p)
100{
101 //
102 // Add a point to the fit
103 //
104
105 if (!Propagate(p)) return kFALSE;
106 Double_t chi2=GetPredictedChi2(p);
107 if (chi2>fMaxChi2) return kFALSE;
108 if (!Update(p,chi2)) return kFALSE;
109
110 return kTRUE;
111}
112
113
114Double_t AliTrackFitterKalman::GetPredictedChi2(const AliTrackPoint *p) const {
115 //
116 // Calculate the predicted chi2 increment.
117 //
118
119 Float_t txyz[3]={GetParam()[0],GetParam()[1],GetParam()[2]};
120 TMatrixDSym &cv=*fCov;
121 Float_t tcov[6]={
122 cv(0,0),cv(1,0),cv(2,0),
123 cv(1,1),cv(2,1),
124 cv(2,2)
125 };
126 AliTrackPoint tp(txyz,tcov,p->GetVolumeID());
127
128 Double_t chi2=p->GetResidual(tp,kTRUE);
129
130 return chi2;
131}
132
133
134Bool_t AliTrackFitterKalman::Propagate(const AliTrackPoint *p) {
135 //
136 // Propagate the track towards the measured point "p"
137 //
138
139 TMatrixDSym &cv=*fCov;
140 Double_t s=p->GetY() - fParams[1];
141 Double_t sig2=s*s/12.;
142
143 Double_t vx=fParams[3], vz=fParams[4];
144 fParams[0] += s*vx;
145 fParams[1] += s;
146 fParams[2] += s*vz;
147
148 Double_t
149 c00 = cv(0,0) + 2*s*cv(3,0) + s*s*cv(3,3) + vx*vx*sig2,
150
151 c10 = cv(1,0) + s*cv(1,3) + vx*sig2, c11=cv(1,1) + sig2,
152
153 c20 = cv(2,0) + s*(cv(4,0) + cv(2,3)) + s*s*cv(4,3) + vx*vz*sig2,
154 c21 = cv(2,1) + s*cv(4,1) + vz*sig2,
155 c22 = cv(2,2) + 2*s*cv(4,2) + s*s*cv(4,4) + vz*vz*sig2,
156
157 c30 = cv(3,0) + s*cv(3,3), c31 = cv(3,1),
158 c32 = cv(3,2) + s*cv(3,4), c33 = cv(3,3),
159
160 c40 = cv(4,0) + s*cv(4,3), c41 = cv(4,1),
161 c42 = cv(4,2) + s*cv(4,4), c43 = cv(4,3), c44 = cv(4,4);
162
163
164 cv(0,0)=c00; cv(0,1)=c10; cv(0,2)=c20; cv(0,3)=c30; cv(0,4)=c40;
165 cv(1,0)=c10; cv(1,1)=c11; cv(1,2)=c21; cv(1,3)=c31; cv(1,4)=c41;
166 cv(2,0)=c20; cv(2,1)=c21; cv(2,2)=c22; cv(2,3)=c32; cv(2,4)=c42;
167 cv(3,0)=c30; cv(3,1)=c31; cv(3,2)=c32; cv(3,3)=c33; cv(3,4)=c43;
168 cv(4,0)=c40; cv(4,1)=c41; cv(4,2)=c42; cv(4,3)=c43; cv(4,4)=c44;
169
170 return kTRUE;
171}
172
173Bool_t AliTrackFitterKalman::Update(const AliTrackPoint *p, Double_t chi2) {
174 //
175 // Update the track params using the measured point "p"
176 //
177
178 TMatrixDSym &c=*fCov;
179 const Float_t *cov=p->GetCov();
180
181 TMatrixDSym v(3);
182 v(0,0)=cov[0]+c(0,0); v(0,1)=cov[1]+c(0,1); v(0,2)=cov[2]+c(0,2);
183 v(1,0)=cov[1]+c(1,0); v(1,1)=cov[3]+c(1,1); v(1,2)=cov[4]+c(1,2);
184 v(2,0)=cov[2]+c(2,0); v(2,1)=cov[4]+c(2,1); v(2,2)=cov[5]+c(2,2);
2bece746 185 if (TMath::Abs(v.Determinant()) < 1.e-33) return kFALSE;
9c4c8863 186 v.Invert();
187
188 TMatrixD ch(5,3);
189 ch(0,0)=c(0,0); ch(0,1)=c(0,1); ch(0,2)=c(0,2);
190 ch(1,0)=c(1,0); ch(1,1)=c(1,1); ch(1,2)=c(1,2);
191 ch(2,0)=c(2,0); ch(2,1)=c(2,1); ch(2,2)=c(2,2);
192 ch(3,0)=c(3,0); ch(3,1)=c(3,1); ch(3,2)=c(3,2);
193 ch(4,0)=c(4,0); ch(4,1)=c(4,1); ch(4,2)=c(4,2);
194
195 TMatrixD k(ch,TMatrixD::kMult,v);
196
197 TMatrixD d(3,1);
198 d(0,0) = p->GetX() - fParams[0];
199 d(1,0) = p->GetY() - fParams[1];
200 d(2,0) = p->GetZ() - fParams[2];
201
202 TMatrixD x(k,TMatrixD::kMult,d);
203
204 fParams[0]+=x(0,0);
205 fParams[1]+=x(1,0);
206 fParams[2]+=x(2,0);
207 fParams[3]+=x(3,0);
208 fParams[4]+=x(4,0);
209
210 TMatrixD hc(3,5);
211 hc(0,0)=c(0,0);hc(0,1)=c(0,1);hc(0,2)=c(0,2);hc(0,3)=c(0,3);hc(0,4)=c(0,4);
212 hc(1,0)=c(1,0);hc(1,1)=c(1,1);hc(1,2)=c(1,2);hc(1,3)=c(1,3);hc(1,4)=c(1,4);
213 hc(2,0)=c(2,0);hc(2,1)=c(2,1);hc(2,2)=c(2,2);hc(2,3)=c(2,3);hc(2,4)=c(2,4);
214
215 TMatrixD s(k,TMatrixD::kMult,hc);
216
217 c(0,0)-=s(0,0);c(0,1)-=s(0,1);c(0,2)-=s(0,2);c(0,3)-=s(0,3);c(0,4)-=s(0,4);
218 c(1,0)-=s(1,0);c(1,1)-=s(1,1);c(1,2)-=s(1,2);c(1,3)-=s(1,3);c(1,4)-=s(1,4);
219 c(2,0)-=s(2,0);c(2,1)-=s(2,1);c(2,2)-=s(2,2);c(2,3)-=s(2,3);c(2,4)-=s(2,4);
220 c(3,0)-=s(3,0);c(3,1)-=s(3,1);c(3,2)-=s(3,2);c(3,3)-=s(3,3);c(3,4)-=s(3,4);
221 c(4,0)-=s(4,0);c(4,1)-=s(4,1);c(4,2)-=s(4,2);c(4,3)-=s(4,3);c(4,4)-=s(4,4);
222
223 fChi2 += chi2;
224 fNdf += 2;
225
226 return kTRUE;
227}
228
229//_____________________________________________________________________________
230Bool_t AliTrackFitterKalman::GetPCA(const AliTrackPoint &p, AliTrackPoint &i) const
231{
232 //
233 // Get the intersection point "i" between the track and the plane
234 // the point "p" belongs to.
235 //
236
237 TMatrixD t(3,1);
238 Double_t s=p.GetY() - fParams[1];
239 Double_t vx=fParams[3], vz=fParams[4];
240 t(0,0) = fParams[0] + s*vx;
241 t(1,0) = fParams[1] + s;
242 t(2,0) = fParams[2] + s*vz;
243
244 TMatrixDSym tC(3);
245 {
246 Double_t sig2=s*s/12.;
93a7cb17 247
248 tC(0,0) = vx*vx*sig2;
249 tC(1,0) = vx*sig2;
250 tC(1,1) = sig2;
251 tC(2,0) = vx*vz*sig2;
252 tC(2,1) = vz*sig2;
253 tC(2,2) = vz*vz*sig2;
9c4c8863 254
255 tC(0,1) = tC(1,0); tC(0,2) = tC(2,0);
256 tC(1,2) = tC(2,1);
257 }
258
259 TMatrixD m(3,1);
260 m(0,0)=p.GetX();
261 m(1,0)=p.GetY();
262 m(2,0)=p.GetZ();
263
264 TMatrixDSym mC(3);
265 {
266 const Float_t *cv=p.GetCov();
267 mC(0,0)=cv[0]; mC(0,1)=cv[1]; mC(0,2)=cv[2];
268 mC(1,0)=cv[1]; mC(1,1)=cv[3]; mC(1,2)=cv[4];
269 mC(2,0)=cv[2]; mC(2,1)=cv[4]; mC(2,2)=cv[5];
270 }
271
272 TMatrixDSym tmW(tC);
273 tmW+=mC;
2bece746 274 if (TMath::Abs(tmW.Determinant()) < 1.e-33) return kFALSE;
9c4c8863 275 tmW.Invert();
276
11721007 277 TMatrixD mW(tC,TMatrixD::kMult,tmW);
278 TMatrixD tW(mC,TMatrixD::kMult,tmW);
9c4c8863 279
280 TMatrixD mi(mW,TMatrixD::kMult,m);
281 TMatrixD ti(tW,TMatrixD::kMult,t);
282 ti+=mi;
283
284 TMatrixD iC(tC,TMatrixD::kMult,tmW);
285 iC*=mC;
21404e08 286 Double_t sig2=1.; // Releasing the matrix by 1 cm along the track direction
287 iC(0,0) += vx*vx*sig2;
288 iC(0,1) += vx*sig2;
289 iC(1,1) += sig2;
290 iC(0,2) += vx*vz*sig2;
291 iC(1,2) += vz*sig2;
292 iC(2,2) += vz*vz*sig2;
293
9c4c8863 294
295 Float_t cov[6]={
296 iC(0,0), iC(0,1), iC(0,2),
297 iC(1,1), iC(1,2),
298 iC(2,2)
299 };
300 i.SetXYZ(ti(0,0),ti(1,0),ti(2,0),cov);
301 UShort_t id=p.GetVolumeID();
302 i.SetVolumeID(id);
303
304 return kTRUE;
305}
306
307
308//_____________________________________________________________________________
309void
310AliTrackFitterKalman::SetSeed(const Double_t par[5], const Double_t cov[15]) {
311 //
312 // Set the initial approximation for the track parameters
313 //
314 for (Int_t i=0; i<5; i++) fParams[i]=par[i];
315 fParams[5]=0.;
316
317 delete fCov;
318 fCov=new TMatrixDSym(5);
319 TMatrixDSym &cv=*fCov;
320
321 cv(0,0)=cov[0 ];
322 cv(1,0)=cov[1 ]; cv(1,1)=cov[2 ];
323 cv(2,0)=cov[3 ]; cv(2,1)=cov[4 ]; cv(2,2)=cov[5 ];
324 cv(3,0)=cov[6 ]; cv(3,1)=cov[7 ]; cv(3,2)=cov[8 ]; cv(3,3)=cov[9 ];
325 cv(4,0)=cov[10]; cv(4,1)=cov[11]; cv(4,2)=cov[12]; cv(4,3)=cov[13]; cv(4,4)=cov[14];
326
327 cv(0,1)=cv(1,0);
328 cv(0,2)=cv(2,0); cv(1,2)=cv(2,1);
329 cv(0,3)=cv(3,0); cv(1,3)=cv(3,1); cv(2,3)=cv(3,2);
330 cv(0,4)=cv(4,0); cv(1,4)=cv(4,1); cv(2,4)=cv(4,2); cv(3,4)=cv(4,3);
331
57c8a1c2 332 fSeed=kTRUE;
9c4c8863 333}