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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" | |
f37d970d | 25 | #include "AliLog.h" |
74f9526e | 26 | #include "AliPDG.h" |
27 | #include "TPDGCode.h" | |
28 | #include "TDatabasePDG.h" | |
87594435 | 29 | |
30 | ClassImp(AliKalmanTrack) | |
31 | ||
116cbefd | 32 | Double_t AliKalmanTrack::fgConvConst; |
9b280d80 | 33 | |
e2afb3b6 | 34 | //_______________________________________________________________________ |
35 | AliKalmanTrack::AliKalmanTrack(): | |
36 | fLab(-3141593), | |
37 | fChi2(0), | |
38 | fMass(0.13957), | |
39 | fN(0) | |
40 | { | |
116cbefd | 41 | // |
42 | // Default constructor | |
43 | // | |
8de97894 | 44 | if (fgConvConst==0) { |
f37d970d | 45 | AliFatal("The magnetic field has not been set!"); |
8de97894 | 46 | } |
74f9526e | 47 | |
48 | fStartTimeIntegral = kFALSE; | |
49 | fIntegratedLength = 0; | |
50 | for(Int_t i=0; i<5; i++) fIntegratedTime[i] = 0; | |
e2afb3b6 | 51 | } |
52 | ||
53 | //_______________________________________________________________________ | |
54 | AliKalmanTrack::AliKalmanTrack(const AliKalmanTrack &t): | |
55 | TObject(t), | |
56 | fLab(t.fLab), | |
babd135a | 57 | fFakeRatio(t.fFakeRatio), |
e2afb3b6 | 58 | fChi2(t.fChi2), |
59 | fMass(t.fMass), | |
60 | fN(t.fN) | |
61 | { | |
116cbefd | 62 | // |
63 | // Copy constructor | |
64 | // | |
8de97894 | 65 | if (fgConvConst==0) { |
f37d970d | 66 | AliFatal("The magnetic field has not been set!"); |
8de97894 | 67 | } |
74f9526e | 68 | |
69 | fStartTimeIntegral = t.fStartTimeIntegral; | |
70 | fIntegratedLength = t.fIntegratedLength; | |
71 | ||
72 | for (Int_t i=0; i<5; i++) | |
73 | fIntegratedTime[i] = t.fIntegratedTime[i]; | |
74 | } | |
c5507f6d | 75 | |
76 | //_______________________________________________________________________ | |
77 | Double_t AliKalmanTrack::GetX() const | |
78 | { | |
fc7be9e3 | 79 | // Returns the X coordinate of the current track position |
f37d970d | 80 | AliWarning("Method must be overloaded !"); |
c5507f6d | 81 | return 0.; |
82 | } | |
83 | //_______________________________________________________________________ | |
84 | Double_t AliKalmanTrack::GetdEdx() const | |
85 | { | |
fc7be9e3 | 86 | // Returns the dE/dx of the track |
f37d970d | 87 | AliWarning("Method must be overloaded !"); |
c5507f6d | 88 | return 0.; |
89 | } | |
90 | ||
91 | //_______________________________________________________________________ | |
92 | Double_t AliKalmanTrack::GetY() const | |
93 | { | |
fc7be9e3 | 94 | // Returns the Y coordinate of the current track position |
c5507f6d | 95 | Double_t par[5]; |
96 | Double_t localX = GetX(); | |
97 | GetExternalParameters(localX, par); | |
98 | return par[0]; | |
99 | } | |
100 | //_______________________________________________________________________ | |
101 | Double_t AliKalmanTrack::GetZ() const | |
102 | { | |
fc7be9e3 | 103 | // Returns the Z coordinate of the current track position |
c5507f6d | 104 | Double_t par[5]; |
105 | Double_t localX = GetX(); | |
106 | GetExternalParameters(localX, par); | |
107 | return par[1]; | |
108 | } | |
109 | //_______________________________________________________________________ | |
110 | Double_t AliKalmanTrack::GetSnp() const | |
111 | { | |
fc7be9e3 | 112 | // Returns the Sin(phi), where phi is the angle between the transverse |
113 | // momentum (in xOy plane) and the X axis | |
c5507f6d | 114 | Double_t par[5]; |
115 | Double_t localX = GetX(); | |
116 | GetExternalParameters(localX, par); | |
117 | return par[2]; | |
118 | } | |
119 | //_______________________________________________________________________ | |
120 | Double_t AliKalmanTrack::GetTgl() const | |
121 | { | |
fc7be9e3 | 122 | // Returns the Tan(lambda), where lambda is the dip angle (between |
123 | // the bending plane (xOy) and the momentum of the track | |
c5507f6d | 124 | Double_t par[5]; |
125 | Double_t localX = GetX(); | |
126 | GetExternalParameters(localX, par); | |
127 | return par[3]; | |
128 | } | |
129 | //_______________________________________________________________________ | |
130 | Double_t AliKalmanTrack::Get1Pt() const | |
131 | { | |
fc7be9e3 | 132 | // Returns 1/pT |
c5507f6d | 133 | Double_t par[5]; |
134 | Double_t localX = GetX(); | |
135 | GetExternalParameters(localX, par); | |
136 | return par[4]; | |
137 | } | |
138 | ||
139 | //_______________________________________________________________________ | |
140 | Double_t AliKalmanTrack::Phi() const | |
141 | { | |
142 | // return global phi of track | |
143 | ||
144 | Double_t par[5]; | |
145 | Double_t localX = GetX(); | |
146 | GetExternalParameters(localX, par); | |
79e94bf8 | 147 | if (par[2] > 1.) par[2] = 1.; |
148 | if (par[2] < -1.) par[2] = -1.; | |
c5507f6d | 149 | Double_t phi = TMath::ASin(par[2]) + GetAlpha(); |
150 | while (phi < 0) phi += TMath::TwoPi(); | |
151 | while (phi > TMath::TwoPi()) phi -= TMath::TwoPi(); | |
152 | return phi; | |
153 | } | |
154 | //_______________________________________________________________________ | |
155 | Double_t AliKalmanTrack::SigmaPhi() const | |
156 | { | |
157 | // return error of global phi of track | |
158 | ||
159 | Double_t par[5]; | |
160 | Double_t cov[15]; | |
161 | Double_t localX = GetX(); | |
162 | GetExternalParameters(localX, par); | |
163 | GetExternalCovariance(cov); | |
164 | return TMath::Sqrt(TMath::Abs(cov[5] / (1. - par[2]*par[2]))); | |
165 | } | |
166 | //_______________________________________________________________________ | |
167 | Double_t AliKalmanTrack::Theta() const | |
168 | { | |
169 | // return global theta of track | |
170 | ||
171 | Double_t par[5]; | |
172 | Double_t localX = GetX(); | |
173 | GetExternalParameters(localX, par); | |
174 | return TMath::Pi()/2. - TMath::ATan(par[3]); | |
175 | } | |
176 | //_______________________________________________________________________ | |
177 | Double_t AliKalmanTrack::SigmaTheta() const | |
178 | { | |
179 | // return error of global theta of track | |
180 | ||
181 | Double_t par[5]; | |
182 | Double_t cov[15]; | |
183 | Double_t localX = GetX(); | |
184 | GetExternalParameters(localX, par); | |
185 | GetExternalCovariance(cov); | |
186 | return TMath::Sqrt(TMath::Abs(cov[5])) / (1. + par[3]*par[3]); | |
187 | } | |
188 | //_______________________________________________________________________ | |
8de97894 | 189 | Double_t AliKalmanTrack::Eta() const |
190 | { | |
191 | // return global eta of track | |
192 | ||
193 | return -TMath::Log(TMath::Tan(Theta()/2.)); | |
194 | } | |
195 | //_______________________________________________________________________ | |
c5507f6d | 196 | Double_t AliKalmanTrack::Px() const |
197 | { | |
198 | // return x component of track momentum | |
199 | ||
200 | Double_t par[5]; | |
201 | Double_t localX = GetX(); | |
202 | GetExternalParameters(localX, par); | |
203 | Double_t phi = TMath::ASin(par[2]) + GetAlpha(); | |
204 | return TMath::Cos(phi) / TMath::Abs(par[4]); | |
205 | } | |
206 | //_______________________________________________________________________ | |
207 | Double_t AliKalmanTrack::Py() const | |
208 | { | |
209 | // return y 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::Sin(phi) / TMath::Abs(par[4]); | |
216 | } | |
217 | //_______________________________________________________________________ | |
218 | Double_t AliKalmanTrack::Pz() const | |
219 | { | |
220 | // return z component of track momentum | |
221 | ||
222 | Double_t par[5]; | |
223 | Double_t localX = GetX(); | |
224 | GetExternalParameters(localX, par); | |
225 | return par[3] / TMath::Abs(par[4]); | |
226 | } | |
227 | //_______________________________________________________________________ | |
228 | Double_t AliKalmanTrack::Pt() const | |
229 | { | |
230 | // return transverse component of track momentum | |
231 | ||
232 | Double_t par[5]; | |
233 | Double_t localX = GetX(); | |
234 | GetExternalParameters(localX, par); | |
235 | return 1. / TMath::Abs(par[4]); | |
236 | } | |
237 | //_______________________________________________________________________ | |
238 | Double_t AliKalmanTrack::SigmaPt() const | |
239 | { | |
240 | // return error of transverse component of track momentum | |
241 | ||
242 | Double_t par[5]; | |
243 | Double_t cov[15]; | |
244 | Double_t localX = GetX(); | |
245 | GetExternalParameters(localX, par); | |
246 | GetExternalCovariance(cov); | |
247 | return TMath::Sqrt(cov[14]) / TMath::Abs(par[4]); | |
248 | } | |
249 | //_______________________________________________________________________ | |
250 | Double_t AliKalmanTrack::P() const | |
251 | { | |
252 | // return total track momentum | |
253 | ||
254 | Double_t par[5]; | |
255 | Double_t localX = GetX(); | |
256 | GetExternalParameters(localX, par); | |
79e94bf8 | 257 | return 1. / TMath::Abs(par[4] * TMath::Cos(TMath::ATan(par[3]))); |
c5507f6d | 258 | } |
74f9526e | 259 | //_______________________________________________________________________ |
260 | void AliKalmanTrack::StartTimeIntegral() | |
261 | { | |
49a7a79a | 262 | // Sylwester Radomski, GSI |
263 | // S.Radomski@gsi.de | |
74f9526e | 264 | // |
265 | // Start time integration | |
266 | // To be called at Vertex by ITS tracker | |
267 | // | |
268 | ||
269 | //if (fStartTimeIntegral) | |
f37d970d | 270 | // AliWarning("Reseting Recorded Time."); |
74f9526e | 271 | |
272 | fStartTimeIntegral = kTRUE; | |
5d8718b8 | 273 | for(Int_t i=0; i<fgkTypes; i++) fIntegratedTime[i] = 0; |
74f9526e | 274 | fIntegratedLength = 0; |
275 | } | |
276 | //_______________________________________________________________________ | |
277 | void AliKalmanTrack:: AddTimeStep(Double_t length) | |
278 | { | |
279 | // | |
280 | // Add step to integrated time | |
281 | // this method should be called by a sublasses at the end | |
282 | // of the PropagateTo function or by a tracker | |
283 | // each time step is made. | |
284 | // | |
285 | // If integration not started function does nothing | |
286 | // | |
287 | // Formula | |
288 | // dt = dl * sqrt(p^2 + m^2) / p | |
289 | // p = pT * (1 + tg^2 (lambda) ) | |
290 | // | |
291 | // pt = 1/external parameter [4] | |
292 | // tg lambda = external parameter [3] | |
293 | // | |
294 | // | |
295 | // Sylwester Radomski, GSI | |
296 | // S.Radomski@gsi.de | |
297 | // | |
298 | ||
5d8718b8 | 299 | static const Double_t kcc = 2.99792458e-2; |
74f9526e | 300 | |
301 | if (!fStartTimeIntegral) return; | |
302 | ||
303 | fIntegratedLength += length; | |
304 | ||
5d8718b8 | 305 | static Int_t pdgCode[fgkTypes] = {kElectron, kMuonMinus, kPiPlus, kKPlus, kProton}; |
74f9526e | 306 | TDatabasePDG *db = TDatabasePDG::Instance(); |
307 | ||
308 | Double_t xr, param[5]; | |
309 | Double_t pt, tgl; | |
310 | ||
311 | GetExternalParameters(xr, param); | |
312 | pt = 1/param[4] ; | |
313 | tgl = param[3]; | |
314 | ||
315 | Double_t p = TMath::Abs(pt * TMath::Sqrt(1+tgl*tgl)); | |
316 | ||
317 | if (length > 100) return; | |
318 | ||
5d8718b8 | 319 | for (Int_t i=0; i<fgkTypes; i++) { |
74f9526e | 320 | |
321 | Double_t mass = db->GetParticle(pdgCode[i])->Mass(); | |
322 | Double_t correction = TMath::Sqrt( pt*pt * (1 + tgl*tgl) + mass * mass ) / p; | |
5d8718b8 | 323 | Double_t time = length * correction / kcc; |
74f9526e | 324 | |
74f9526e | 325 | fIntegratedTime[i] += time; |
326 | } | |
e2afb3b6 | 327 | } |
328 | ||
74f9526e | 329 | //_______________________________________________________________________ |
330 | ||
331 | Double_t AliKalmanTrack::GetIntegratedTime(Int_t pdg) const | |
332 | { | |
49a7a79a | 333 | // Sylwester Radomski, GSI |
334 | // S.Radomski@gsi.de | |
74f9526e | 335 | // |
336 | // Return integrated time hypothesis for a given particle | |
337 | // type assumption. | |
338 | // | |
339 | // Input parameter: | |
340 | // pdg - Pdg code of a particle type | |
341 | // | |
342 | ||
343 | ||
344 | if (!fStartTimeIntegral) { | |
f37d970d | 345 | AliWarning("Time integration not started"); |
74f9526e | 346 | return 0.; |
347 | } | |
348 | ||
5d8718b8 | 349 | static Int_t pdgCode[fgkTypes] = {kElectron, kMuonMinus, kPiPlus, kKPlus, kProton}; |
74f9526e | 350 | |
5d8718b8 | 351 | for (Int_t i=0; i<fgkTypes; i++) |
74f9526e | 352 | if (pdgCode[i] == TMath::Abs(pdg)) return fIntegratedTime[i]; |
353 | ||
f37d970d | 354 | AliWarning(Form("Particle type [%d] not found", pdg)); |
74f9526e | 355 | return 0; |
356 | } | |
ae982df3 | 357 | |
358 | void AliKalmanTrack::GetIntegratedTimes(Double_t *times) const { | |
359 | for (Int_t i=0; i<fgkTypes; i++) times[i]=fIntegratedTime[i]; | |
360 | } | |
361 | ||
362 | void AliKalmanTrack::SetIntegratedTimes(const Double_t *times) { | |
363 | for (Int_t i=0; i<fgkTypes; i++) fIntegratedTime[i]=times[i]; | |
364 | } | |
365 | ||
74f9526e | 366 | //_______________________________________________________________________ |
367 | ||
368 | void AliKalmanTrack::PrintTime() const | |
369 | { | |
49a7a79a | 370 | // Sylwester Radomski, GSI |
371 | // S.Radomski@gsi.de | |
372 | // | |
74f9526e | 373 | // For testing |
374 | // Prints time for all hypothesis | |
375 | // | |
376 | ||
5d8718b8 | 377 | static Int_t pdgCode[fgkTypes] = {kElectron, kMuonMinus, kPiPlus, kKPlus, kProton}; |
74f9526e | 378 | |
5d8718b8 | 379 | for (Int_t i=0; i<fgkTypes; i++) |
74f9526e | 380 | printf("%d: %.2f ", pdgCode[i], fIntegratedTime[i]); |
381 | printf("\n"); | |
382 | } | |
383 | ||
49a7a79a | 384 | static void External2Helix(const AliKalmanTrack *t, Double_t helix[6]) { |
385 | //-------------------------------------------------------------------- | |
386 | // External track parameters -> helix parameters | |
387 | //-------------------------------------------------------------------- | |
388 | Double_t alpha,x,cs,sn; | |
389 | t->GetExternalParameters(x,helix); alpha=t->GetAlpha(); | |
390 | ||
391 | cs=TMath::Cos(alpha); sn=TMath::Sin(alpha); | |
392 | helix[5]=x*cs - helix[0]*sn; // x0 | |
393 | helix[0]=x*sn + helix[0]*cs; // y0 | |
394 | //helix[1]= // z0 | |
395 | helix[2]=TMath::ASin(helix[2]) + alpha; // phi0 | |
396 | //helix[3]= // tgl | |
397 | helix[4]=helix[4]/t->GetConvConst(); // C | |
398 | } | |
399 | ||
400 | static void Evaluate(const Double_t *h, Double_t t, | |
401 | Double_t r[3], //radius vector | |
402 | Double_t g[3], //first defivatives | |
403 | Double_t gg[3]) //second derivatives | |
404 | { | |
405 | //-------------------------------------------------------------------- | |
406 | // Calculate position of a point on a track and some derivatives | |
407 | //-------------------------------------------------------------------- | |
408 | Double_t phase=h[4]*t+h[2]; | |
409 | Double_t sn=TMath::Sin(phase), cs=TMath::Cos(phase); | |
410 | ||
411 | r[0] = h[5] + (sn - h[6])/h[4]; | |
412 | r[1] = h[0] - (cs - h[7])/h[4]; | |
413 | r[2] = h[1] + h[3]*t; | |
414 | ||
415 | g[0] = cs; g[1]=sn; g[2]=h[3]; | |
416 | ||
417 | gg[0]=-h[4]*sn; gg[1]=h[4]*cs; gg[2]=0.; | |
418 | } | |
419 | ||
420 | Double_t AliKalmanTrack:: | |
421 | GetDCA(const AliKalmanTrack *p, Double_t &xthis, Double_t &xp) const { | |
422 | //------------------------------------------------------------ | |
423 | // Returns the (weighed !) distance of closest approach between | |
424 | // this track and the track passed as the argument. | |
425 | // Other returned values: | |
426 | // xthis, xt - coordinates of tracks' reference planes at the DCA | |
427 | //----------------------------------------------------------- | |
428 | Double_t dy2=GetSigmaY2() + p->GetSigmaY2(); | |
429 | Double_t dz2=GetSigmaZ2() + p->GetSigmaZ2(); | |
430 | Double_t dx2=dy2; | |
431 | ||
432 | //dx2=dy2=dz2=1.; | |
433 | ||
434 | Double_t p1[8]; External2Helix(this,p1); | |
435 | p1[6]=TMath::Sin(p1[2]); p1[7]=TMath::Cos(p1[2]); | |
436 | Double_t p2[8]; External2Helix(p,p2); | |
437 | p2[6]=TMath::Sin(p2[2]); p2[7]=TMath::Cos(p2[2]); | |
438 | ||
439 | ||
440 | Double_t r1[3],g1[3],gg1[3]; Double_t t1=0.; | |
441 | Evaluate(p1,t1,r1,g1,gg1); | |
442 | Double_t r2[3],g2[3],gg2[3]; Double_t t2=0.; | |
443 | Evaluate(p2,t2,r2,g2,gg2); | |
74f9526e | 444 | |
49a7a79a | 445 | Double_t dx=r2[0]-r1[0], dy=r2[1]-r1[1], dz=r2[2]-r1[2]; |
446 | Double_t dm=dx*dx/dx2 + dy*dy/dy2 + dz*dz/dz2; | |
447 | ||
448 | Int_t max=27; | |
449 | while (max--) { | |
450 | Double_t gt1=-(dx*g1[0]/dx2 + dy*g1[1]/dy2 + dz*g1[2]/dz2); | |
451 | Double_t gt2=+(dx*g2[0]/dx2 + dy*g2[1]/dy2 + dz*g2[2]/dz2); | |
452 | Double_t h11=(g1[0]*g1[0] - dx*gg1[0])/dx2 + | |
453 | (g1[1]*g1[1] - dy*gg1[1])/dy2 + | |
454 | (g1[2]*g1[2] - dz*gg1[2])/dz2; | |
455 | Double_t h22=(g2[0]*g2[0] + dx*gg2[0])/dx2 + | |
456 | (g2[1]*g2[1] + dy*gg2[1])/dy2 + | |
457 | (g2[2]*g2[2] + dz*gg2[2])/dz2; | |
458 | Double_t h12=-(g1[0]*g2[0]/dx2 + g1[1]*g2[1]/dy2 + g1[2]*g2[2]/dz2); | |
459 | ||
460 | Double_t det=h11*h22-h12*h12; | |
461 | ||
462 | Double_t dt1,dt2; | |
463 | if (TMath::Abs(det)<1.e-33) { | |
464 | //(quasi)singular Hessian | |
465 | dt1=-gt1; dt2=-gt2; | |
466 | } else { | |
467 | dt1=-(gt1*h22 - gt2*h12)/det; | |
468 | dt2=-(h11*gt2 - h12*gt1)/det; | |
469 | } | |
470 | ||
471 | if ((dt1*gt1+dt2*gt2)>0) {dt1=-dt1; dt2=-dt2;} | |
472 | ||
473 | //check delta(phase1) ? | |
474 | //check delta(phase2) ? | |
475 | ||
476 | if (TMath::Abs(dt1)/(TMath::Abs(t1)+1.e-3) < 1.e-4) | |
477 | if (TMath::Abs(dt2)/(TMath::Abs(t2)+1.e-3) < 1.e-4) { | |
478 | if ((gt1*gt1+gt2*gt2) > 1.e-4/dy2/dy2) | |
f37d970d | 479 | AliWarning(" stopped at not a stationary point !"); |
49a7a79a | 480 | Double_t lmb=h11+h22; lmb=lmb-TMath::Sqrt(lmb*lmb-4*det); |
481 | if (lmb < 0.) | |
f37d970d | 482 | AliWarning(" stopped at not a minimum !"); |
49a7a79a | 483 | break; |
484 | } | |
485 | ||
486 | Double_t dd=dm; | |
487 | for (Int_t div=1 ; ; div*=2) { | |
488 | Evaluate(p1,t1+dt1,r1,g1,gg1); | |
489 | Evaluate(p2,t2+dt2,r2,g2,gg2); | |
490 | dx=r2[0]-r1[0]; dy=r2[1]-r1[1]; dz=r2[2]-r1[2]; | |
491 | dd=dx*dx/dx2 + dy*dy/dy2 + dz*dz/dz2; | |
492 | if (dd<dm) break; | |
493 | dt1*=0.5; dt2*=0.5; | |
494 | if (div>512) { | |
f37d970d | 495 | AliWarning(" overshoot !"); break; |
49a7a79a | 496 | } |
497 | } | |
498 | dm=dd; | |
499 | ||
500 | t1+=dt1; | |
501 | t2+=dt2; | |
502 | ||
503 | } | |
504 | ||
f37d970d | 505 | if (max<=0) AliWarning(" too many iterations !"); |
49a7a79a | 506 | |
507 | Double_t cs=TMath::Cos(GetAlpha()); | |
508 | Double_t sn=TMath::Sin(GetAlpha()); | |
509 | xthis=r1[0]*cs + r1[1]*sn; | |
510 | ||
511 | cs=TMath::Cos(p->GetAlpha()); | |
512 | sn=TMath::Sin(p->GetAlpha()); | |
513 | xp=r2[0]*cs + r2[1]*sn; | |
514 | ||
515 | return TMath::Sqrt(dm*TMath::Sqrt(dy2*dz2)); | |
516 | } | |
517 | ||
518 | Double_t AliKalmanTrack:: | |
519 | PropagateToDCA(AliKalmanTrack *p, Double_t d, Double_t x0) { | |
520 | //-------------------------------------------------------------- | |
521 | // Propagates this track and the argument track to the position of the | |
522 | // distance of closest approach. | |
523 | // Returns the (weighed !) distance of closest approach. | |
524 | //-------------------------------------------------------------- | |
525 | Double_t xthis,xp; | |
526 | Double_t dca=GetDCA(p,xthis,xp); | |
527 | ||
528 | if (!PropagateTo(xthis,d,x0)) { | |
f37d970d | 529 | //AliWarning(" propagation failed !"); |
49a7a79a | 530 | return 1e+33; |
531 | } | |
532 | ||
533 | if (!p->PropagateTo(xp,d,x0)) { | |
f37d970d | 534 | //AliWarning(" propagation failed !"; |
49a7a79a | 535 | return 1e+33; |
536 | } | |
537 | ||
538 | return dca; | |
539 | } |