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87594435 | 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 | ||
acd84897 | 16 | /* $Id$ */ |
fb17acd4 | 17 | |
87594435 | 18 | //------------------------------------------------------------------------- |
19 | // Implementation of the AliKalmanTrack class | |
066782e8 | 20 | // that is the base for AliTPCtrack, AliITStrackV2 and AliTRDtrack |
87594435 | 21 | // Origin: Iouri Belikov, CERN, Jouri.Belikov@cern.ch |
22 | //------------------------------------------------------------------------- | |
23 | ||
24 | #include "AliKalmanTrack.h" | |
74f9526e | 25 | #include "AliPDG.h" |
26 | #include "TPDGCode.h" | |
27 | #include "TDatabasePDG.h" | |
8de97894 | 28 | #include "AliRunLoader.h" |
29 | #include "AliRun.h" | |
30 | #include "AliMagF.h" | |
87594435 | 31 | |
32 | ClassImp(AliKalmanTrack) | |
33 | ||
116cbefd | 34 | Double_t AliKalmanTrack::fgConvConst; |
9b280d80 | 35 | |
e2afb3b6 | 36 | //_______________________________________________________________________ |
37 | AliKalmanTrack::AliKalmanTrack(): | |
38 | fLab(-3141593), | |
39 | fChi2(0), | |
40 | fMass(0.13957), | |
41 | fN(0) | |
42 | { | |
116cbefd | 43 | // |
44 | // Default constructor | |
45 | // | |
8de97894 | 46 | if (fgConvConst==0) { |
47 | Warning("AliKalmanTrack()", "The magnetic field has not been set!"); | |
48 | SetConvConst(); | |
49 | } | |
74f9526e | 50 | |
51 | fStartTimeIntegral = kFALSE; | |
52 | fIntegratedLength = 0; | |
53 | for(Int_t i=0; i<5; i++) fIntegratedTime[i] = 0; | |
e2afb3b6 | 54 | } |
55 | ||
56 | //_______________________________________________________________________ | |
57 | AliKalmanTrack::AliKalmanTrack(const AliKalmanTrack &t): | |
58 | TObject(t), | |
59 | fLab(t.fLab), | |
60 | fChi2(t.fChi2), | |
61 | fMass(t.fMass), | |
62 | fN(t.fN) | |
63 | { | |
116cbefd | 64 | // |
65 | // Copy constructor | |
66 | // | |
8de97894 | 67 | if (fgConvConst==0) { |
68 | Warning("AliKalmanTrack(const AliKalmanTrack&)", | |
69 | "The magnetic field has not been set!"); | |
70 | SetConvConst(); | |
71 | } | |
74f9526e | 72 | |
73 | fStartTimeIntegral = t.fStartTimeIntegral; | |
74 | fIntegratedLength = t.fIntegratedLength; | |
75 | ||
76 | for (Int_t i=0; i<5; i++) | |
77 | fIntegratedTime[i] = t.fIntegratedTime[i]; | |
78 | } | |
c5507f6d | 79 | |
8de97894 | 80 | |
81 | //_______________________________________________________________________ | |
82 | void AliKalmanTrack::SetConvConst() | |
83 | { | |
84 | ::Info("SetConvConst()", "tryinig to get the magnetic field from the AliRun object..."); | |
85 | AliRunLoader* loader = AliRunLoader::GetRunLoader(); | |
86 | if (!loader) ::Fatal("SetConvConst()", "No run loader found"); | |
87 | if (!loader->GetAliRun()) loader->LoadgAlice(); | |
88 | AliRun* alirun = loader->GetAliRun(); | |
89 | if (!alirun) ::Fatal("SetConvConst()", "No AliRun object found"); | |
90 | ||
91 | Double_t field = alirun->Field()->SolenoidField(); | |
92 | SetConvConst(1000/0.299792458/field); | |
93 | ::Info("SetConvConst()", "Magnetic field set to %f kGauss\n", field); | |
94 | } | |
95 | ||
c5507f6d | 96 | //_______________________________________________________________________ |
97 | Double_t AliKalmanTrack::GetX() const | |
98 | { | |
99 | Warning("GetX()","Method must be overloaded !\n"); | |
100 | return 0.; | |
101 | } | |
102 | //_______________________________________________________________________ | |
103 | Double_t AliKalmanTrack::GetdEdx() const | |
104 | { | |
105 | Warning("GetdEdx()","Method must be overloaded !\n"); | |
106 | return 0.; | |
107 | } | |
108 | ||
109 | //_______________________________________________________________________ | |
110 | Double_t AliKalmanTrack::GetY() const | |
111 | { | |
112 | Double_t par[5]; | |
113 | Double_t localX = GetX(); | |
114 | GetExternalParameters(localX, par); | |
115 | return par[0]; | |
116 | } | |
117 | //_______________________________________________________________________ | |
118 | Double_t AliKalmanTrack::GetZ() const | |
119 | { | |
120 | Double_t par[5]; | |
121 | Double_t localX = GetX(); | |
122 | GetExternalParameters(localX, par); | |
123 | return par[1]; | |
124 | } | |
125 | //_______________________________________________________________________ | |
126 | Double_t AliKalmanTrack::GetSnp() const | |
127 | { | |
128 | Double_t par[5]; | |
129 | Double_t localX = GetX(); | |
130 | GetExternalParameters(localX, par); | |
131 | return par[2]; | |
132 | } | |
133 | //_______________________________________________________________________ | |
134 | Double_t AliKalmanTrack::GetTgl() const | |
135 | { | |
136 | Double_t par[5]; | |
137 | Double_t localX = GetX(); | |
138 | GetExternalParameters(localX, par); | |
139 | return par[3]; | |
140 | } | |
141 | //_______________________________________________________________________ | |
142 | Double_t AliKalmanTrack::Get1Pt() const | |
143 | { | |
144 | Double_t par[5]; | |
145 | Double_t localX = GetX(); | |
146 | GetExternalParameters(localX, par); | |
147 | return par[4]; | |
148 | } | |
149 | ||
150 | //_______________________________________________________________________ | |
151 | Double_t AliKalmanTrack::Phi() const | |
152 | { | |
153 | // return global phi of track | |
154 | ||
155 | Double_t par[5]; | |
156 | Double_t localX = GetX(); | |
157 | GetExternalParameters(localX, par); | |
79e94bf8 | 158 | if (par[2] > 1.) par[2] = 1.; |
159 | if (par[2] < -1.) par[2] = -1.; | |
c5507f6d | 160 | Double_t phi = TMath::ASin(par[2]) + GetAlpha(); |
161 | while (phi < 0) phi += TMath::TwoPi(); | |
162 | while (phi > TMath::TwoPi()) phi -= TMath::TwoPi(); | |
163 | return phi; | |
164 | } | |
165 | //_______________________________________________________________________ | |
166 | Double_t AliKalmanTrack::SigmaPhi() const | |
167 | { | |
168 | // return error of global phi of track | |
169 | ||
170 | Double_t par[5]; | |
171 | Double_t cov[15]; | |
172 | Double_t localX = GetX(); | |
173 | GetExternalParameters(localX, par); | |
174 | GetExternalCovariance(cov); | |
175 | return TMath::Sqrt(TMath::Abs(cov[5] / (1. - par[2]*par[2]))); | |
176 | } | |
177 | //_______________________________________________________________________ | |
178 | Double_t AliKalmanTrack::Theta() const | |
179 | { | |
180 | // return global theta of track | |
181 | ||
182 | Double_t par[5]; | |
183 | Double_t localX = GetX(); | |
184 | GetExternalParameters(localX, par); | |
185 | return TMath::Pi()/2. - TMath::ATan(par[3]); | |
186 | } | |
187 | //_______________________________________________________________________ | |
188 | Double_t AliKalmanTrack::SigmaTheta() const | |
189 | { | |
190 | // return error of global theta of track | |
191 | ||
192 | Double_t par[5]; | |
193 | Double_t cov[15]; | |
194 | Double_t localX = GetX(); | |
195 | GetExternalParameters(localX, par); | |
196 | GetExternalCovariance(cov); | |
197 | return TMath::Sqrt(TMath::Abs(cov[5])) / (1. + par[3]*par[3]); | |
198 | } | |
199 | //_______________________________________________________________________ | |
8de97894 | 200 | Double_t AliKalmanTrack::Eta() const |
201 | { | |
202 | // return global eta of track | |
203 | ||
204 | return -TMath::Log(TMath::Tan(Theta()/2.)); | |
205 | } | |
206 | //_______________________________________________________________________ | |
c5507f6d | 207 | Double_t AliKalmanTrack::Px() const |
208 | { | |
209 | // return x component of track momentum | |
210 | ||
211 | Double_t par[5]; | |
212 | Double_t localX = GetX(); | |
213 | GetExternalParameters(localX, par); | |
214 | Double_t phi = TMath::ASin(par[2]) + GetAlpha(); | |
215 | return TMath::Cos(phi) / TMath::Abs(par[4]); | |
216 | } | |
217 | //_______________________________________________________________________ | |
218 | Double_t AliKalmanTrack::Py() const | |
219 | { | |
220 | // return y component of track momentum | |
221 | ||
222 | Double_t par[5]; | |
223 | Double_t localX = GetX(); | |
224 | GetExternalParameters(localX, par); | |
225 | Double_t phi = TMath::ASin(par[2]) + GetAlpha(); | |
226 | return TMath::Sin(phi) / TMath::Abs(par[4]); | |
227 | } | |
228 | //_______________________________________________________________________ | |
229 | Double_t AliKalmanTrack::Pz() const | |
230 | { | |
231 | // return z component of track momentum | |
232 | ||
233 | Double_t par[5]; | |
234 | Double_t localX = GetX(); | |
235 | GetExternalParameters(localX, par); | |
236 | return par[3] / TMath::Abs(par[4]); | |
237 | } | |
238 | //_______________________________________________________________________ | |
239 | Double_t AliKalmanTrack::Pt() const | |
240 | { | |
241 | // return transverse component of track momentum | |
242 | ||
243 | Double_t par[5]; | |
244 | Double_t localX = GetX(); | |
245 | GetExternalParameters(localX, par); | |
246 | return 1. / TMath::Abs(par[4]); | |
247 | } | |
248 | //_______________________________________________________________________ | |
249 | Double_t AliKalmanTrack::SigmaPt() const | |
250 | { | |
251 | // return error of transverse component of track momentum | |
252 | ||
253 | Double_t par[5]; | |
254 | Double_t cov[15]; | |
255 | Double_t localX = GetX(); | |
256 | GetExternalParameters(localX, par); | |
257 | GetExternalCovariance(cov); | |
258 | return TMath::Sqrt(cov[14]) / TMath::Abs(par[4]); | |
259 | } | |
260 | //_______________________________________________________________________ | |
261 | Double_t AliKalmanTrack::P() const | |
262 | { | |
263 | // return total track momentum | |
264 | ||
265 | Double_t par[5]; | |
266 | Double_t localX = GetX(); | |
267 | GetExternalParameters(localX, par); | |
79e94bf8 | 268 | return 1. / TMath::Abs(par[4] * TMath::Cos(TMath::ATan(par[3]))); |
c5507f6d | 269 | } |
74f9526e | 270 | //_______________________________________________________________________ |
271 | void AliKalmanTrack::StartTimeIntegral() | |
272 | { | |
49a7a79a | 273 | // Sylwester Radomski, GSI |
274 | // S.Radomski@gsi.de | |
74f9526e | 275 | // |
276 | // Start time integration | |
277 | // To be called at Vertex by ITS tracker | |
278 | // | |
279 | ||
280 | //if (fStartTimeIntegral) | |
281 | // Warning("StartTimeIntegral", "Reseting Recorded Time."); | |
282 | ||
283 | fStartTimeIntegral = kTRUE; | |
5d8718b8 | 284 | for(Int_t i=0; i<fgkTypes; i++) fIntegratedTime[i] = 0; |
74f9526e | 285 | fIntegratedLength = 0; |
286 | } | |
287 | //_______________________________________________________________________ | |
288 | void AliKalmanTrack:: AddTimeStep(Double_t length) | |
289 | { | |
290 | // | |
291 | // Add step to integrated time | |
292 | // this method should be called by a sublasses at the end | |
293 | // of the PropagateTo function or by a tracker | |
294 | // each time step is made. | |
295 | // | |
296 | // If integration not started function does nothing | |
297 | // | |
298 | // Formula | |
299 | // dt = dl * sqrt(p^2 + m^2) / p | |
300 | // p = pT * (1 + tg^2 (lambda) ) | |
301 | // | |
302 | // pt = 1/external parameter [4] | |
303 | // tg lambda = external parameter [3] | |
304 | // | |
305 | // | |
306 | // Sylwester Radomski, GSI | |
307 | // S.Radomski@gsi.de | |
308 | // | |
309 | ||
5d8718b8 | 310 | static const Double_t kcc = 2.99792458e-2; |
74f9526e | 311 | |
312 | if (!fStartTimeIntegral) return; | |
313 | ||
314 | fIntegratedLength += length; | |
315 | ||
5d8718b8 | 316 | static Int_t pdgCode[fgkTypes] = {kElectron, kMuonMinus, kPiPlus, kKPlus, kProton}; |
74f9526e | 317 | TDatabasePDG *db = TDatabasePDG::Instance(); |
318 | ||
319 | Double_t xr, param[5]; | |
320 | Double_t pt, tgl; | |
321 | ||
322 | GetExternalParameters(xr, param); | |
323 | pt = 1/param[4] ; | |
324 | tgl = param[3]; | |
325 | ||
326 | Double_t p = TMath::Abs(pt * TMath::Sqrt(1+tgl*tgl)); | |
327 | ||
328 | if (length > 100) return; | |
329 | ||
5d8718b8 | 330 | for (Int_t i=0; i<fgkTypes; i++) { |
74f9526e | 331 | |
332 | Double_t mass = db->GetParticle(pdgCode[i])->Mass(); | |
333 | Double_t correction = TMath::Sqrt( pt*pt * (1 + tgl*tgl) + mass * mass ) / p; | |
5d8718b8 | 334 | Double_t time = length * correction / kcc; |
74f9526e | 335 | |
336 | //cout << mass << "\t" << pt << "\t" << p << "\t" | |
337 | // << correction << endl; | |
338 | ||
339 | fIntegratedTime[i] += time; | |
340 | } | |
e2afb3b6 | 341 | } |
342 | ||
74f9526e | 343 | //_______________________________________________________________________ |
344 | ||
345 | Double_t AliKalmanTrack::GetIntegratedTime(Int_t pdg) const | |
346 | { | |
49a7a79a | 347 | // Sylwester Radomski, GSI |
348 | // S.Radomski@gsi.de | |
74f9526e | 349 | // |
350 | // Return integrated time hypothesis for a given particle | |
351 | // type assumption. | |
352 | // | |
353 | // Input parameter: | |
354 | // pdg - Pdg code of a particle type | |
355 | // | |
356 | ||
357 | ||
358 | if (!fStartTimeIntegral) { | |
359 | Warning("GetIntegratedTime","Time integration not started"); | |
360 | return 0.; | |
361 | } | |
362 | ||
5d8718b8 | 363 | static Int_t pdgCode[fgkTypes] = {kElectron, kMuonMinus, kPiPlus, kKPlus, kProton}; |
74f9526e | 364 | |
5d8718b8 | 365 | for (Int_t i=0; i<fgkTypes; i++) |
74f9526e | 366 | if (pdgCode[i] == TMath::Abs(pdg)) return fIntegratedTime[i]; |
367 | ||
368 | Warning(":GetIntegratedTime","Particle type [%d] not found", pdg); | |
369 | return 0; | |
370 | } | |
ae982df3 | 371 | |
372 | void AliKalmanTrack::GetIntegratedTimes(Double_t *times) const { | |
373 | for (Int_t i=0; i<fgkTypes; i++) times[i]=fIntegratedTime[i]; | |
374 | } | |
375 | ||
376 | void AliKalmanTrack::SetIntegratedTimes(const Double_t *times) { | |
377 | for (Int_t i=0; i<fgkTypes; i++) fIntegratedTime[i]=times[i]; | |
378 | } | |
379 | ||
74f9526e | 380 | //_______________________________________________________________________ |
381 | ||
382 | void AliKalmanTrack::PrintTime() const | |
383 | { | |
49a7a79a | 384 | // Sylwester Radomski, GSI |
385 | // S.Radomski@gsi.de | |
386 | // | |
74f9526e | 387 | // For testing |
388 | // Prints time for all hypothesis | |
389 | // | |
390 | ||
5d8718b8 | 391 | static Int_t pdgCode[fgkTypes] = {kElectron, kMuonMinus, kPiPlus, kKPlus, kProton}; |
74f9526e | 392 | |
5d8718b8 | 393 | for (Int_t i=0; i<fgkTypes; i++) |
74f9526e | 394 | printf("%d: %.2f ", pdgCode[i], fIntegratedTime[i]); |
395 | printf("\n"); | |
396 | } | |
397 | ||
49a7a79a | 398 | static void External2Helix(const AliKalmanTrack *t, Double_t helix[6]) { |
399 | //-------------------------------------------------------------------- | |
400 | // External track parameters -> helix parameters | |
401 | //-------------------------------------------------------------------- | |
402 | Double_t alpha,x,cs,sn; | |
403 | t->GetExternalParameters(x,helix); alpha=t->GetAlpha(); | |
404 | ||
405 | cs=TMath::Cos(alpha); sn=TMath::Sin(alpha); | |
406 | helix[5]=x*cs - helix[0]*sn; // x0 | |
407 | helix[0]=x*sn + helix[0]*cs; // y0 | |
408 | //helix[1]= // z0 | |
409 | helix[2]=TMath::ASin(helix[2]) + alpha; // phi0 | |
410 | //helix[3]= // tgl | |
411 | helix[4]=helix[4]/t->GetConvConst(); // C | |
412 | } | |
413 | ||
414 | static void Evaluate(const Double_t *h, Double_t t, | |
415 | Double_t r[3], //radius vector | |
416 | Double_t g[3], //first defivatives | |
417 | Double_t gg[3]) //second derivatives | |
418 | { | |
419 | //-------------------------------------------------------------------- | |
420 | // Calculate position of a point on a track and some derivatives | |
421 | //-------------------------------------------------------------------- | |
422 | Double_t phase=h[4]*t+h[2]; | |
423 | Double_t sn=TMath::Sin(phase), cs=TMath::Cos(phase); | |
424 | ||
425 | r[0] = h[5] + (sn - h[6])/h[4]; | |
426 | r[1] = h[0] - (cs - h[7])/h[4]; | |
427 | r[2] = h[1] + h[3]*t; | |
428 | ||
429 | g[0] = cs; g[1]=sn; g[2]=h[3]; | |
430 | ||
431 | gg[0]=-h[4]*sn; gg[1]=h[4]*cs; gg[2]=0.; | |
432 | } | |
433 | ||
434 | Double_t AliKalmanTrack:: | |
435 | GetDCA(const AliKalmanTrack *p, Double_t &xthis, Double_t &xp) const { | |
436 | //------------------------------------------------------------ | |
437 | // Returns the (weighed !) distance of closest approach between | |
438 | // this track and the track passed as the argument. | |
439 | // Other returned values: | |
440 | // xthis, xt - coordinates of tracks' reference planes at the DCA | |
441 | //----------------------------------------------------------- | |
442 | Double_t dy2=GetSigmaY2() + p->GetSigmaY2(); | |
443 | Double_t dz2=GetSigmaZ2() + p->GetSigmaZ2(); | |
444 | Double_t dx2=dy2; | |
445 | ||
446 | //dx2=dy2=dz2=1.; | |
447 | ||
448 | Double_t p1[8]; External2Helix(this,p1); | |
449 | p1[6]=TMath::Sin(p1[2]); p1[7]=TMath::Cos(p1[2]); | |
450 | Double_t p2[8]; External2Helix(p,p2); | |
451 | p2[6]=TMath::Sin(p2[2]); p2[7]=TMath::Cos(p2[2]); | |
452 | ||
453 | ||
454 | Double_t r1[3],g1[3],gg1[3]; Double_t t1=0.; | |
455 | Evaluate(p1,t1,r1,g1,gg1); | |
456 | Double_t r2[3],g2[3],gg2[3]; Double_t t2=0.; | |
457 | Evaluate(p2,t2,r2,g2,gg2); | |
74f9526e | 458 | |
49a7a79a | 459 | Double_t dx=r2[0]-r1[0], dy=r2[1]-r1[1], dz=r2[2]-r1[2]; |
460 | Double_t dm=dx*dx/dx2 + dy*dy/dy2 + dz*dz/dz2; | |
461 | ||
462 | Int_t max=27; | |
463 | while (max--) { | |
464 | Double_t gt1=-(dx*g1[0]/dx2 + dy*g1[1]/dy2 + dz*g1[2]/dz2); | |
465 | Double_t gt2=+(dx*g2[0]/dx2 + dy*g2[1]/dy2 + dz*g2[2]/dz2); | |
466 | Double_t h11=(g1[0]*g1[0] - dx*gg1[0])/dx2 + | |
467 | (g1[1]*g1[1] - dy*gg1[1])/dy2 + | |
468 | (g1[2]*g1[2] - dz*gg1[2])/dz2; | |
469 | Double_t h22=(g2[0]*g2[0] + dx*gg2[0])/dx2 + | |
470 | (g2[1]*g2[1] + dy*gg2[1])/dy2 + | |
471 | (g2[2]*g2[2] + dz*gg2[2])/dz2; | |
472 | Double_t h12=-(g1[0]*g2[0]/dx2 + g1[1]*g2[1]/dy2 + g1[2]*g2[2]/dz2); | |
473 | ||
474 | Double_t det=h11*h22-h12*h12; | |
475 | ||
476 | Double_t dt1,dt2; | |
477 | if (TMath::Abs(det)<1.e-33) { | |
478 | //(quasi)singular Hessian | |
479 | dt1=-gt1; dt2=-gt2; | |
480 | } else { | |
481 | dt1=-(gt1*h22 - gt2*h12)/det; | |
482 | dt2=-(h11*gt2 - h12*gt1)/det; | |
483 | } | |
484 | ||
485 | if ((dt1*gt1+dt2*gt2)>0) {dt1=-dt1; dt2=-dt2;} | |
486 | ||
487 | //check delta(phase1) ? | |
488 | //check delta(phase2) ? | |
489 | ||
490 | if (TMath::Abs(dt1)/(TMath::Abs(t1)+1.e-3) < 1.e-4) | |
491 | if (TMath::Abs(dt2)/(TMath::Abs(t2)+1.e-3) < 1.e-4) { | |
492 | if ((gt1*gt1+gt2*gt2) > 1.e-4/dy2/dy2) | |
493 | Warning("GetDCA"," stopped at not a stationary point !\n"); | |
494 | Double_t lmb=h11+h22; lmb=lmb-TMath::Sqrt(lmb*lmb-4*det); | |
495 | if (lmb < 0.) | |
496 | Warning("GetDCA"," stopped at not a minimum !\n"); | |
497 | break; | |
498 | } | |
499 | ||
500 | Double_t dd=dm; | |
501 | for (Int_t div=1 ; ; div*=2) { | |
502 | Evaluate(p1,t1+dt1,r1,g1,gg1); | |
503 | Evaluate(p2,t2+dt2,r2,g2,gg2); | |
504 | dx=r2[0]-r1[0]; dy=r2[1]-r1[1]; dz=r2[2]-r1[2]; | |
505 | dd=dx*dx/dx2 + dy*dy/dy2 + dz*dz/dz2; | |
506 | if (dd<dm) break; | |
507 | dt1*=0.5; dt2*=0.5; | |
508 | if (div>512) { | |
509 | Warning("GetDCA"," overshoot !\n"); break; | |
510 | } | |
511 | } | |
512 | dm=dd; | |
513 | ||
514 | t1+=dt1; | |
515 | t2+=dt2; | |
516 | ||
517 | } | |
518 | ||
519 | if (max<=0) Warning("GetDCA"," too many iterations !\n"); | |
520 | ||
521 | Double_t cs=TMath::Cos(GetAlpha()); | |
522 | Double_t sn=TMath::Sin(GetAlpha()); | |
523 | xthis=r1[0]*cs + r1[1]*sn; | |
524 | ||
525 | cs=TMath::Cos(p->GetAlpha()); | |
526 | sn=TMath::Sin(p->GetAlpha()); | |
527 | xp=r2[0]*cs + r2[1]*sn; | |
528 | ||
529 | return TMath::Sqrt(dm*TMath::Sqrt(dy2*dz2)); | |
530 | } | |
531 | ||
532 | Double_t AliKalmanTrack:: | |
533 | PropagateToDCA(AliKalmanTrack *p, Double_t d, Double_t x0) { | |
534 | //-------------------------------------------------------------- | |
535 | // Propagates this track and the argument track to the position of the | |
536 | // distance of closest approach. | |
537 | // Returns the (weighed !) distance of closest approach. | |
538 | //-------------------------------------------------------------- | |
539 | Double_t xthis,xp; | |
540 | Double_t dca=GetDCA(p,xthis,xp); | |
541 | ||
542 | if (!PropagateTo(xthis,d,x0)) { | |
543 | //Warning("PropagateToDCA"," propagation failed !\n"); | |
544 | return 1e+33; | |
545 | } | |
546 | ||
547 | if (!p->PropagateTo(xp,d,x0)) { | |
548 | //Warning("PropagateToDCA"," propagation failed !\n"; | |
549 | return 1e+33; | |
550 | } | |
551 | ||
552 | return dca; | |
553 | } |