Change Float_t to Double32_t (Markus)
[u/mrichter/AliRoot.git] / STEER / AliExternalTrackParam.cxx
CommitLineData
51ad6848 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/* $Id$ */
17
18///////////////////////////////////////////////////////////////////////////////
19// //
49d13e89 20// Implementation of the external track parameterisation class. //
51ad6848 21// //
49d13e89 22// This parameterisation is used to exchange tracks between the detectors. //
23// A set of functions returning the position and the momentum of tracks //
24// in the global coordinate system as well as the track impact parameters //
25// are implemented.
26// Origin: I.Belikov, CERN, Jouri.Belikov@cern.ch //
51ad6848 27///////////////////////////////////////////////////////////////////////////////
4b189f98 28#include <TMatrixDSym.h>
51ad6848 29#include "AliExternalTrackParam.h"
f76701bf 30#include "AliESDVertex.h"
6c94f330 31#include "AliLog.h"
51ad6848 32
33ClassImp(AliExternalTrackParam)
34
ed5f2849 35Double32_t AliExternalTrackParam::fgMostProbablePt=kMostProbablePt;
36
51ad6848 37//_____________________________________________________________________________
90e48c0c 38AliExternalTrackParam::AliExternalTrackParam() :
6c94f330 39 TObject(),
90e48c0c 40 fX(0),
c9ec41e8 41 fAlpha(0)
51ad6848 42{
90e48c0c 43 //
44 // default constructor
45 //
c9ec41e8 46 for (Int_t i = 0; i < 5; i++) fP[i] = 0;
47 for (Int_t i = 0; i < 15; i++) fC[i] = 0;
51ad6848 48}
49
50//_____________________________________________________________________________
6c94f330 51AliExternalTrackParam::AliExternalTrackParam(const AliExternalTrackParam &track):
52 TObject(track),
53 fX(track.fX),
54 fAlpha(track.fAlpha)
55{
56 //
57 // copy constructor
58 //
59 for (Int_t i = 0; i < 5; i++) fP[i] = track.fP[i];
60 for (Int_t i = 0; i < 15; i++) fC[i] = track.fC[i];
61}
62
63//_____________________________________________________________________________
51ad6848 64AliExternalTrackParam::AliExternalTrackParam(Double_t x, Double_t alpha,
65 const Double_t param[5],
90e48c0c 66 const Double_t covar[15]) :
6c94f330 67 TObject(),
90e48c0c 68 fX(x),
c9ec41e8 69 fAlpha(alpha)
51ad6848 70{
90e48c0c 71 //
72 // create external track parameters from given arguments
73 //
c9ec41e8 74 for (Int_t i = 0; i < 5; i++) fP[i] = param[i];
75 for (Int_t i = 0; i < 15; i++) fC[i] = covar[i];
51ad6848 76}
77
90e48c0c 78//_____________________________________________________________________________
6c94f330 79void AliExternalTrackParam::Set(Double_t x, Double_t alpha,
80 const Double_t p[5], const Double_t cov[15]) {
c9ec41e8 81 //
6c94f330 82 // Sets the parameters
c9ec41e8 83 //
6c94f330 84 fX=x;
85 fAlpha=alpha;
86 for (Int_t i = 0; i < 5; i++) fP[i] = p[i];
87 for (Int_t i = 0; i < 15; i++) fC[i] = cov[i];
51ad6848 88}
89
90//_____________________________________________________________________________
c9ec41e8 91void AliExternalTrackParam::Reset() {
1530f89c 92 //
93 // Resets all the parameters to 0
94 //
c9ec41e8 95 fX=fAlpha=0.;
96 for (Int_t i = 0; i < 5; i++) fP[i] = 0;
97 for (Int_t i = 0; i < 15; i++) fC[i] = 0;
51ad6848 98}
99
c9ec41e8 100Double_t AliExternalTrackParam::GetP() const {
101 //---------------------------------------------------------------------
102 // This function returns the track momentum
103 // Results for (nearly) straight tracks are meaningless !
104 //---------------------------------------------------------------------
06fb4a2f 105 if (TMath::Abs(fP[4])<=kAlmost0) return kVeryBig;
c9ec41e8 106 return TMath::Sqrt(1.+ fP[3]*fP[3])/TMath::Abs(fP[4]);
51ad6848 107}
108
1d99986f 109Double_t AliExternalTrackParam::Get1P() const {
110 //---------------------------------------------------------------------
111 // This function returns the 1/(track momentum)
112 //---------------------------------------------------------------------
113 return TMath::Abs(fP[4])/TMath::Sqrt(1.+ fP[3]*fP[3]);
114}
115
c9ec41e8 116//_______________________________________________________________________
c7bafca9 117Double_t AliExternalTrackParam::GetD(Double_t x,Double_t y,Double_t b) const {
c9ec41e8 118 //------------------------------------------------------------------
119 // This function calculates the transverse impact parameter
120 // with respect to a point with global coordinates (x,y)
121 // in the magnetic field "b" (kG)
122 //------------------------------------------------------------------
5773defd 123 if (TMath::Abs(b) < kAlmost0Field) return GetLinearD(x,y);
1530f89c 124 Double_t rp4=GetC(b);
c9ec41e8 125
126 Double_t xt=fX, yt=fP[0];
127
128 Double_t sn=TMath::Sin(fAlpha), cs=TMath::Cos(fAlpha);
129 Double_t a = x*cs + y*sn;
130 y = -x*sn + y*cs; x=a;
131 xt-=x; yt-=y;
132
133 sn=rp4*xt - fP[2]; cs=rp4*yt + TMath::Sqrt(1.- fP[2]*fP[2]);
134 a=2*(xt*fP[2] - yt*TMath::Sqrt(1.- fP[2]*fP[2]))-rp4*(xt*xt + yt*yt);
1530f89c 135 return -a/(1 + TMath::Sqrt(sn*sn + cs*cs));
136}
137
138//_______________________________________________________________________
139void AliExternalTrackParam::
140GetDZ(Double_t x, Double_t y, Double_t z, Double_t b, Float_t dz[2]) const {
141 //------------------------------------------------------------------
142 // This function calculates the transverse and longitudinal impact parameters
143 // with respect to a point with global coordinates (x,y)
144 // in the magnetic field "b" (kG)
145 //------------------------------------------------------------------
146 Double_t f1 = fP[2], r1 = TMath::Sqrt(1. - f1*f1);
147 Double_t xt=fX, yt=fP[0];
148 Double_t sn=TMath::Sin(fAlpha), cs=TMath::Cos(fAlpha);
149 Double_t a = x*cs + y*sn;
150 y = -x*sn + y*cs; x=a;
151 xt-=x; yt-=y;
152
153 Double_t rp4=GetC(b);
154 if ((TMath::Abs(b) < kAlmost0Field) || (TMath::Abs(rp4) < kAlmost0)) {
155 dz[0] = -(xt*f1 - yt*r1);
156 dz[1] = fP[1] + (dz[0]*f1 - xt)/r1*fP[3] - z;
157 return;
158 }
159
160 sn=rp4*xt - f1; cs=rp4*yt + r1;
161 a=2*(xt*f1 - yt*r1)-rp4*(xt*xt + yt*yt);
162 Double_t rr=TMath::Sqrt(sn*sn + cs*cs);
163 dz[0] = -a/(1 + rr);
164 Double_t f2 = -sn/rr, r2 = TMath::Sqrt(1. - f2*f2);
165 dz[1] = fP[1] + fP[3]/rp4*TMath::ASin(f2*r1 - f1*r2) - z;
51ad6848 166}
167
49d13e89 168//_______________________________________________________________________
169Double_t AliExternalTrackParam::GetLinearD(Double_t xv,Double_t yv) const {
170 //------------------------------------------------------------------
171 // This function calculates the transverse impact parameter
172 // with respect to a point with global coordinates (xv,yv)
173 // neglecting the track curvature.
174 //------------------------------------------------------------------
175 Double_t sn=TMath::Sin(fAlpha), cs=TMath::Cos(fAlpha);
176 Double_t x= xv*cs + yv*sn;
177 Double_t y=-xv*sn + yv*cs;
178
179 Double_t d = (fX-x)*fP[2] - (fP[0]-y)*TMath::Sqrt(1.- fP[2]*fP[2]);
180
1530f89c 181 return -d;
49d13e89 182}
183
116b445b 184Bool_t AliExternalTrackParam::CorrectForMeanMaterial
185(Double_t xOverX0, Double_t xTimesRho, Double_t mass,
186Double_t (*Bethe)(Double_t)) {
187 //------------------------------------------------------------------
188 // This function corrects the track parameters for the crossed material.
189 // "xOverX0" - X/X0, the thickness in units of the radiation length.
190 // "xTimesRho" - is the product length*density (g/cm^2).
191 // "mass" - the mass of this particle (GeV/c^2).
192 //------------------------------------------------------------------
193 Double_t &fP2=fP[2];
194 Double_t &fP3=fP[3];
195 Double_t &fP4=fP[4];
196
197 Double_t &fC22=fC[5];
198 Double_t &fC33=fC[9];
199 Double_t &fC43=fC[13];
200 Double_t &fC44=fC[14];
201
202 Double_t p=GetP();
203 Double_t p2=p*p;
204 Double_t beta2=p2/(p2 + mass*mass);
205 xOverX0*=TMath::Sqrt((1.+ fP3*fP3)/(1.- fP2*fP2));
206
207 //Multiple scattering******************
208 if (xOverX0 != 0) {
209 Double_t theta2=14.1*14.1/(beta2*p2*1e6)*TMath::Abs(xOverX0);
210 //Double_t theta2=1.0259e-6*14*14/28/(beta2*p2)*TMath::Abs(d)*9.36*2.33;
211 fC22 += theta2*(1.- fP2*fP2)*(1. + fP3*fP3);
212 fC33 += theta2*(1. + fP3*fP3)*(1. + fP3*fP3);
213 fC43 += theta2*fP3*fP4*(1. + fP3*fP3);
214 fC44 += theta2*fP3*fP4*fP3*fP4;
215 }
216
217 //Energy losses************************
218 if ((xTimesRho != 0.) && (beta2 < 1.)) {
219 Double_t dE=Bethe(beta2)*xTimesRho;
220 Double_t e=TMath::Sqrt(p2 + mass*mass);
221 if ( TMath::Abs(dE) > 0.3*e ) return kFALSE; //30% energy loss is too much!
222 fP4*=(1.- e/p2*dE);
223
224 // Approximate energy loss fluctuation (M.Ivanov)
225 const Double_t knst=0.07; // To be tuned.
226 Double_t sigmadE=knst*TMath::Sqrt(TMath::Abs(dE));
227 fC44+=((sigmadE*e/p2*fP4)*(sigmadE*e/p2*fP4));
228
229 }
230
231 return kTRUE;
232}
233
234
ee5dba5e 235Bool_t AliExternalTrackParam::CorrectForMaterial
236(Double_t d, Double_t x0, Double_t mass, Double_t (*Bethe)(Double_t)) {
c7bafca9 237 //------------------------------------------------------------------
116b445b 238 // Deprecated function !
239 // Better use CorrectForMeanMaterial instead of it.
240 //
c7bafca9 241 // This function corrects the track parameters for the crossed material
242 // "d" - the thickness (fraction of the radiation length)
243 // "x0" - the radiation length (g/cm^2)
244 // "mass" - the mass of this particle (GeV/c^2)
245 //------------------------------------------------------------------
246 Double_t &fP2=fP[2];
247 Double_t &fP3=fP[3];
248 Double_t &fP4=fP[4];
249
250 Double_t &fC22=fC[5];
251 Double_t &fC33=fC[9];
252 Double_t &fC43=fC[13];
253 Double_t &fC44=fC[14];
254
7b5ef2e6 255 Double_t p=GetP();
256 Double_t p2=p*p;
c7bafca9 257 Double_t beta2=p2/(p2 + mass*mass);
258 d*=TMath::Sqrt((1.+ fP3*fP3)/(1.- fP2*fP2));
259
260 //Multiple scattering******************
261 if (d!=0) {
262 Double_t theta2=14.1*14.1/(beta2*p2*1e6)*TMath::Abs(d);
263 //Double_t theta2=1.0259e-6*14*14/28/(beta2*p2)*TMath::Abs(d)*9.36*2.33;
264 fC22 += theta2*(1.- fP2*fP2)*(1. + fP3*fP3);
265 fC33 += theta2*(1. + fP3*fP3)*(1. + fP3*fP3);
266 fC43 += theta2*fP3*fP4*(1. + fP3*fP3);
267 fC44 += theta2*fP3*fP4*fP3*fP4;
268 }
269
270 //Energy losses************************
8fc1985d 271 if (x0!=0. && beta2<1) {
c7bafca9 272 d*=x0;
ee5dba5e 273 Double_t dE=Bethe(beta2)*d;
274 Double_t e=TMath::Sqrt(p2 + mass*mass);
ae666100 275 if ( TMath::Abs(dE) > 0.3*e ) return kFALSE; //30% energy loss is too much!
ee5dba5e 276 fP4*=(1.- e/p2*dE);
277
278 // Approximate energy loss fluctuation (M.Ivanov)
ed5f2849 279 const Double_t knst=0.07; // To be tuned.
280 Double_t sigmadE=knst*TMath::Sqrt(TMath::Abs(dE));
ee5dba5e 281 fC44+=((sigmadE*e/p2*fP4)*(sigmadE*e/p2*fP4));
282
c7bafca9 283 }
284
285 return kTRUE;
286}
287
ee5dba5e 288Double_t ApproximateBetheBloch(Double_t beta2) {
289 //------------------------------------------------------------------
290 // This is an approximation of the Bethe-Bloch formula with
291 // the density effect taken into account at beta*gamma > 3.5
292 // (the approximation is reasonable only for solid materials)
293 //------------------------------------------------------------------
294 if (beta2/(1-beta2)>3.5*3.5)
295 return 0.153e-3/beta2*(log(3.5*5940)+0.5*log(beta2/(1-beta2)) - beta2);
296
297 return 0.153e-3/beta2*(log(5940*beta2/(1-beta2)) - beta2);
298}
299
49d13e89 300Bool_t AliExternalTrackParam::Rotate(Double_t alpha) {
301 //------------------------------------------------------------------
302 // Transform this track to the local coord. system rotated
303 // by angle "alpha" (rad) with respect to the global coord. system.
304 //------------------------------------------------------------------
dfcef74c 305 if (TMath::Abs(fP[2]) >= kAlmost1) {
306 AliError(Form("Precondition is not satisfied: |sin(phi)|>1 ! %f",fP[2]));
307 return kFALSE;
308 }
309
49d13e89 310 if (alpha < -TMath::Pi()) alpha += 2*TMath::Pi();
311 else if (alpha >= TMath::Pi()) alpha -= 2*TMath::Pi();
312
313 Double_t &fP0=fP[0];
314 Double_t &fP2=fP[2];
315 Double_t &fC00=fC[0];
316 Double_t &fC10=fC[1];
317 Double_t &fC20=fC[3];
318 Double_t &fC21=fC[4];
319 Double_t &fC22=fC[5];
320 Double_t &fC30=fC[6];
321 Double_t &fC32=fC[8];
322 Double_t &fC40=fC[10];
323 Double_t &fC42=fC[12];
324
325 Double_t x=fX;
326 Double_t ca=TMath::Cos(alpha-fAlpha), sa=TMath::Sin(alpha-fAlpha);
327 Double_t sf=fP2, cf=TMath::Sqrt(1.- fP2*fP2);
328
dfcef74c 329 Double_t tmp=sf*ca - cf*sa;
330 if (TMath::Abs(tmp) >= kAlmost1) return kFALSE;
331
49d13e89 332 fAlpha = alpha;
333 fX = x*ca + fP0*sa;
334 fP0= -x*sa + fP0*ca;
dfcef74c 335 fP2= tmp;
49d13e89 336
06fb4a2f 337 if (TMath::Abs(cf)<kAlmost0) {
338 AliError(Form("Too small cosine value %f",cf));
339 cf = kAlmost0;
340 }
341
49d13e89 342 Double_t rr=(ca+sf/cf*sa);
343
344 fC00 *= (ca*ca);
345 fC10 *= ca;
346 fC20 *= ca*rr;
347 fC21 *= rr;
348 fC22 *= rr*rr;
349 fC30 *= ca;
350 fC32 *= rr;
351 fC40 *= ca;
352 fC42 *= rr;
353
354 return kTRUE;
355}
356
357Bool_t AliExternalTrackParam::PropagateTo(Double_t xk, Double_t b) {
358 //----------------------------------------------------------------
359 // Propagate this track to the plane X=xk (cm) in the field "b" (kG)
360 //----------------------------------------------------------------
49d13e89 361 Double_t dx=xk-fX;
e421f556 362 if (TMath::Abs(dx)<=kAlmost0) return kTRUE;
18ebc5ef 363
1530f89c 364 Double_t crv=GetC(b);
5773defd 365 if (TMath::Abs(b) < kAlmost0Field) crv=0.;
366
49d13e89 367 Double_t f1=fP[2], f2=f1 + crv*dx;
bbefa4c4 368 if (TMath::Abs(f1) >= kAlmost1) return kFALSE;
49d13e89 369 if (TMath::Abs(f2) >= kAlmost1) return kFALSE;
370
371 Double_t &fP0=fP[0], &fP1=fP[1], &fP2=fP[2], &fP3=fP[3], &fP4=fP[4];
372 Double_t
373 &fC00=fC[0],
374 &fC10=fC[1], &fC11=fC[2],
375 &fC20=fC[3], &fC21=fC[4], &fC22=fC[5],
376 &fC30=fC[6], &fC31=fC[7], &fC32=fC[8], &fC33=fC[9],
377 &fC40=fC[10], &fC41=fC[11], &fC42=fC[12], &fC43=fC[13], &fC44=fC[14];
378
379 Double_t r1=TMath::Sqrt(1.- f1*f1), r2=TMath::Sqrt(1.- f2*f2);
380
381 fX=xk;
382 fP0 += dx*(f1+f2)/(r1+r2);
18ebc5ef 383 fP1 += dx*(r2 + f2*(f1+f2)/(r1+r2))*fP3; // Many thanks to P.Hristov !
49d13e89 384 fP2 += dx*crv;
385
386 //f = F - 1
387
388 Double_t f02= dx/(r1*r1*r1); Double_t cc=crv/fP4;
389 Double_t f04=0.5*dx*dx/(r1*r1*r1); f04*=cc;
390 Double_t f12= dx*fP3*f1/(r1*r1*r1);
391 Double_t f14=0.5*dx*dx*fP3*f1/(r1*r1*r1); f14*=cc;
392 Double_t f13= dx/r1;
393 Double_t f24= dx; f24*=cc;
394
395 //b = C*ft
396 Double_t b00=f02*fC20 + f04*fC40, b01=f12*fC20 + f14*fC40 + f13*fC30;
397 Double_t b02=f24*fC40;
398 Double_t b10=f02*fC21 + f04*fC41, b11=f12*fC21 + f14*fC41 + f13*fC31;
399 Double_t b12=f24*fC41;
400 Double_t b20=f02*fC22 + f04*fC42, b21=f12*fC22 + f14*fC42 + f13*fC32;
401 Double_t b22=f24*fC42;
402 Double_t b40=f02*fC42 + f04*fC44, b41=f12*fC42 + f14*fC44 + f13*fC43;
403 Double_t b42=f24*fC44;
404 Double_t b30=f02*fC32 + f04*fC43, b31=f12*fC32 + f14*fC43 + f13*fC33;
405 Double_t b32=f24*fC43;
406
407 //a = f*b = f*C*ft
408 Double_t a00=f02*b20+f04*b40,a01=f02*b21+f04*b41,a02=f02*b22+f04*b42;
409 Double_t a11=f12*b21+f14*b41+f13*b31,a12=f12*b22+f14*b42+f13*b32;
410 Double_t a22=f24*b42;
411
412 //F*C*Ft = C + (b + bt + a)
413 fC00 += b00 + b00 + a00;
414 fC10 += b10 + b01 + a01;
415 fC20 += b20 + b02 + a02;
416 fC30 += b30;
417 fC40 += b40;
418 fC11 += b11 + b11 + a11;
419 fC21 += b21 + b12 + a12;
420 fC31 += b31;
421 fC41 += b41;
422 fC22 += b22 + b22 + a22;
423 fC32 += b32;
424 fC42 += b42;
425
426 return kTRUE;
427}
428
052daaff 429void AliExternalTrackParam::Propagate(Double_t len, Double_t x[3],
430Double_t p[3], Double_t bz) const {
431 //+++++++++++++++++++++++++++++++++++++++++
432 // Origin: K. Shileev (Kirill.Shileev@cern.ch)
433 // Extrapolate track along simple helix in magnetic field
434 // Arguments: len -distance alogn helix, [cm]
435 // bz - mag field, [kGaus]
436 // Returns: x and p contain extrapolated positon and momentum
437 // The momentum returned for straight-line tracks is meaningless !
438 //+++++++++++++++++++++++++++++++++++++++++
439 GetXYZ(x);
440
59c0deea 441 if (TMath::Abs(Get1Pt()) < kAlmost0 || TMath::Abs(bz) < kAlmost0Field ){ //straight-line tracks
052daaff 442 Double_t unit[3]; GetDirection(unit);
443 x[0]+=unit[0]*len;
444 x[1]+=unit[1]*len;
445 x[2]+=unit[2]*len;
446
447 p[0]=unit[0]/kAlmost0;
448 p[1]=unit[1]/kAlmost0;
449 p[2]=unit[2]/kAlmost0;
450 } else {
451 GetPxPyPz(p);
452 Double_t pp=GetP();
453 Double_t a = -kB2C*bz*GetSign();
454 Double_t rho = a/pp;
455 x[0] += p[0]*TMath::Sin(rho*len)/a - p[1]*(1-TMath::Cos(rho*len))/a;
456 x[1] += p[1]*TMath::Sin(rho*len)/a + p[0]*(1-TMath::Cos(rho*len))/a;
457 x[2] += p[2]*len/pp;
458
459 Double_t p0=p[0];
460 p[0] = p0 *TMath::Cos(rho*len) - p[1]*TMath::Sin(rho*len);
461 p[1] = p[1]*TMath::Cos(rho*len) + p0 *TMath::Sin(rho*len);
462 }
463}
464
465Bool_t AliExternalTrackParam::Intersect(Double_t pnt[3], Double_t norm[3],
466Double_t bz) const {
467 //+++++++++++++++++++++++++++++++++++++++++
468 // Origin: K. Shileev (Kirill.Shileev@cern.ch)
469 // Finds point of intersection (if exists) of the helix with the plane.
470 // Stores result in fX and fP.
471 // Arguments: planePoint,planeNorm - the plane defined by any plane's point
472 // and vector, normal to the plane
473 // Returns: kTrue if helix intersects the plane, kFALSE otherwise.
474 //+++++++++++++++++++++++++++++++++++++++++
475 Double_t x0[3]; GetXYZ(x0); //get track position in MARS
476
477 //estimates initial helix length up to plane
478 Double_t s=
479 (pnt[0]-x0[0])*norm[0] + (pnt[1]-x0[1])*norm[1] + (pnt[2]-x0[2])*norm[2];
480 Double_t dist=99999,distPrev=dist;
481 Double_t x[3],p[3];
482 while(TMath::Abs(dist)>0.00001){
483 //calculates helix at the distance s from x0 ALONG the helix
484 Propagate(s,x,p,bz);
485
486 //distance between current helix position and plane
487 dist=(x[0]-pnt[0])*norm[0]+(x[1]-pnt[1])*norm[1]+(x[2]-pnt[2])*norm[2];
488
489 if(TMath::Abs(dist) >= TMath::Abs(distPrev)) {return kFALSE;}
490 distPrev=dist;
491 s-=dist;
492 }
493 //on exit pnt is intersection point,norm is track vector at that point,
494 //all in MARS
495 for (Int_t i=0; i<3; i++) {pnt[i]=x[i]; norm[i]=p[i];}
496 return kTRUE;
497}
498
49d13e89 499Double_t
500AliExternalTrackParam::GetPredictedChi2(Double_t p[2],Double_t cov[3]) const {
501 //----------------------------------------------------------------
502 // Estimate the chi2 of the space point "p" with the cov. matrix "cov"
503 //----------------------------------------------------------------
504 Double_t sdd = fC[0] + cov[0];
505 Double_t sdz = fC[1] + cov[1];
506 Double_t szz = fC[2] + cov[2];
507 Double_t det = sdd*szz - sdz*sdz;
508
509 if (TMath::Abs(det) < kAlmost0) return kVeryBig;
510
511 Double_t d = fP[0] - p[0];
512 Double_t z = fP[1] - p[1];
513
514 return (d*szz*d - 2*d*sdz*z + z*sdd*z)/det;
515}
516
4b189f98 517Double_t AliExternalTrackParam::
518GetPredictedChi2(Double_t p[3],Double_t covyz[3],Double_t covxyz[3]) const {
519 //----------------------------------------------------------------
520 // Estimate the chi2 of the 3D space point "p" and
1e023a36 521 // the full covariance matrix "covyz" and "covxyz"
4b189f98 522 //
523 // Cov(x,x) ... : covxyz[0]
524 // Cov(y,x) ... : covxyz[1] covyz[0]
525 // Cov(z,x) ... : covxyz[2] covyz[1] covyz[2]
526 //----------------------------------------------------------------
527
528 Double_t res[3] = {
529 GetX() - p[0],
530 GetY() - p[1],
531 GetZ() - p[2]
532 };
533
534 Double_t f=GetSnp();
535 if (TMath::Abs(f) >= kAlmost1) return kVeryBig;
536 Double_t r=TMath::Sqrt(1.- f*f);
537 Double_t a=f/r, b=GetTgl()/r;
538
539 Double_t s2=333.*333.; //something reasonably big (cm^2)
540
541 TMatrixDSym v(3);
542 v(0,0)= s2; v(0,1)= a*s2; v(0,2)= b*s2;;
543 v(1,0)=a*s2; v(1,1)=a*a*s2 + GetSigmaY2(); v(1,2)=a*b*s2 + GetSigmaZY();
544 v(2,0)=b*s2; v(2,1)=a*b*s2 + GetSigmaZY(); v(2,2)=b*b*s2 + GetSigmaZ2();
545
546 v(0,0)+=covxyz[0]; v(0,1)+=covxyz[1]; v(0,2)+=covxyz[2];
547 v(1,0)+=covxyz[1]; v(1,1)+=covyz[0]; v(1,2)+=covyz[1];
548 v(2,0)+=covxyz[2]; v(2,1)+=covyz[1]; v(2,2)+=covyz[2];
549
550 v.Invert();
551 if (!v.IsValid()) return kVeryBig;
552
553 Double_t chi2=0.;
554 for (Int_t i = 0; i < 3; i++)
555 for (Int_t j = 0; j < 3; j++) chi2 += res[i]*res[j]*v(i,j);
556
557 return chi2;
558
559
560}
561
1e023a36 562Bool_t AliExternalTrackParam::
563PropagateTo(Double_t p[3],Double_t covyz[3],Double_t covxyz[3],Double_t bz) {
564 //----------------------------------------------------------------
565 // Propagate this track to the plane
566 // the 3D space point "p" (with the covariance matrix "covyz" and "covxyz")
567 // belongs to.
568 // The magnetic field is "bz" (kG)
569 //
570 // The track curvature and the change of the covariance matrix
571 // of the track parameters are negleted !
572 // (So the "step" should be small compared with 1/curvature)
573 //----------------------------------------------------------------
574
575 Double_t f=GetSnp();
576 if (TMath::Abs(f) >= kAlmost1) return kFALSE;
577 Double_t r=TMath::Sqrt(1.- f*f);
578 Double_t a=f/r, b=GetTgl()/r;
579
580 Double_t s2=333.*333.; //something reasonably big (cm^2)
581
582 TMatrixDSym tV(3);
583 tV(0,0)= s2; tV(0,1)= a*s2; tV(0,2)= b*s2;
584 tV(1,0)=a*s2; tV(1,1)=a*a*s2; tV(1,2)=a*b*s2;
585 tV(2,0)=b*s2; tV(2,1)=a*b*s2; tV(2,2)=b*b*s2;
586
587 TMatrixDSym pV(3);
588 pV(0,0)=covxyz[0]; pV(0,1)=covxyz[1]; pV(0,2)=covxyz[2];
589 pV(1,0)=covxyz[1]; pV(1,1)=covyz[0]; pV(1,2)=covyz[1];
590 pV(2,0)=covxyz[2]; pV(2,1)=covyz[1]; pV(2,2)=covyz[2];
591
592 TMatrixDSym tpV(tV);
593 tpV+=pV;
594 tpV.Invert();
595 if (!tpV.IsValid()) return kFALSE;
596
597 TMatrixDSym pW(3),tW(3);
598 for (Int_t i=0; i<3; i++)
599 for (Int_t j=0; j<3; j++) {
600 pW(i,j)=tW(i,j)=0.;
601 for (Int_t k=0; k<3; k++) {
602 pW(i,j) += tV(i,k)*tpV(k,j);
603 tW(i,j) += pV(i,k)*tpV(k,j);
604 }
605 }
606
607 Double_t t[3] = {GetX(), GetY(), GetZ()};
608
609 Double_t x=0.;
610 for (Int_t i=0; i<3; i++) x += (tW(0,i)*t[i] + pW(0,i)*p[i]);
611 Double_t crv=GetC(bz);
612 if (TMath::Abs(b) < kAlmost0Field) crv=0.;
613 f += crv*(x-fX);
614 if (TMath::Abs(f) >= kAlmost1) return kFALSE;
615 fX=x;
616
617 fP[0]=0.;
618 for (Int_t i=0; i<3; i++) fP[0] += (tW(1,i)*t[i] + pW(1,i)*p[i]);
619 fP[1]=0.;
620 for (Int_t i=0; i<3; i++) fP[1] += (tW(2,i)*t[i] + pW(2,i)*p[i]);
621
622 return kTRUE;
623}
624
49d13e89 625Bool_t AliExternalTrackParam::Update(Double_t p[2], Double_t cov[3]) {
626 //------------------------------------------------------------------
627 // Update the track parameters with the space point "p" having
628 // the covariance matrix "cov"
629 //------------------------------------------------------------------
630 Double_t &fP0=fP[0], &fP1=fP[1], &fP2=fP[2], &fP3=fP[3], &fP4=fP[4];
631 Double_t
632 &fC00=fC[0],
633 &fC10=fC[1], &fC11=fC[2],
634 &fC20=fC[3], &fC21=fC[4], &fC22=fC[5],
635 &fC30=fC[6], &fC31=fC[7], &fC32=fC[8], &fC33=fC[9],
636 &fC40=fC[10], &fC41=fC[11], &fC42=fC[12], &fC43=fC[13], &fC44=fC[14];
637
638 Double_t r00=cov[0], r01=cov[1], r11=cov[2];
639 r00+=fC00; r01+=fC10; r11+=fC11;
640 Double_t det=r00*r11 - r01*r01;
641
642 if (TMath::Abs(det) < kAlmost0) return kFALSE;
643
644
645 Double_t tmp=r00; r00=r11/det; r11=tmp/det; r01=-r01/det;
646
647 Double_t k00=fC00*r00+fC10*r01, k01=fC00*r01+fC10*r11;
648 Double_t k10=fC10*r00+fC11*r01, k11=fC10*r01+fC11*r11;
649 Double_t k20=fC20*r00+fC21*r01, k21=fC20*r01+fC21*r11;
650 Double_t k30=fC30*r00+fC31*r01, k31=fC30*r01+fC31*r11;
651 Double_t k40=fC40*r00+fC41*r01, k41=fC40*r01+fC41*r11;
652
653 Double_t dy=p[0] - fP0, dz=p[1] - fP1;
654 Double_t sf=fP2 + k20*dy + k21*dz;
655 if (TMath::Abs(sf) > kAlmost1) return kFALSE;
656
657 fP0 += k00*dy + k01*dz;
658 fP1 += k10*dy + k11*dz;
659 fP2 = sf;
660 fP3 += k30*dy + k31*dz;
661 fP4 += k40*dy + k41*dz;
662
663 Double_t c01=fC10, c02=fC20, c03=fC30, c04=fC40;
664 Double_t c12=fC21, c13=fC31, c14=fC41;
665
666 fC00-=k00*fC00+k01*fC10; fC10-=k00*c01+k01*fC11;
667 fC20-=k00*c02+k01*c12; fC30-=k00*c03+k01*c13;
668 fC40-=k00*c04+k01*c14;
669
670 fC11-=k10*c01+k11*fC11;
671 fC21-=k10*c02+k11*c12; fC31-=k10*c03+k11*c13;
672 fC41-=k10*c04+k11*c14;
673
674 fC22-=k20*c02+k21*c12; fC32-=k20*c03+k21*c13;
675 fC42-=k20*c04+k21*c14;
676
677 fC33-=k30*c03+k31*c13;
678 fC43-=k30*c04+k31*c14;
679
680 fC44-=k40*c04+k41*c14;
681
682 return kTRUE;
683}
684
c7bafca9 685void
686AliExternalTrackParam::GetHelixParameters(Double_t hlx[6], Double_t b) const {
687 //--------------------------------------------------------------------
688 // External track parameters -> helix parameters
689 // "b" - magnetic field (kG)
690 //--------------------------------------------------------------------
691 Double_t cs=TMath::Cos(fAlpha), sn=TMath::Sin(fAlpha);
692
1530f89c 693 hlx[0]=fP[0]; hlx[1]=fP[1]; hlx[2]=fP[2]; hlx[3]=fP[3];
c7bafca9 694
695 hlx[5]=fX*cs - hlx[0]*sn; // x0
696 hlx[0]=fX*sn + hlx[0]*cs; // y0
697//hlx[1]= // z0
698 hlx[2]=TMath::ASin(hlx[2]) + fAlpha; // phi0
699//hlx[3]= // tgl
1530f89c 700 hlx[4]=GetC(b); // C
c7bafca9 701}
702
703
704static void Evaluate(const Double_t *h, Double_t t,
705 Double_t r[3], //radius vector
706 Double_t g[3], //first defivatives
707 Double_t gg[3]) //second derivatives
708{
709 //--------------------------------------------------------------------
710 // Calculate position of a point on a track and some derivatives
711 //--------------------------------------------------------------------
712 Double_t phase=h[4]*t+h[2];
713 Double_t sn=TMath::Sin(phase), cs=TMath::Cos(phase);
714
715 r[0] = h[5] + (sn - h[6])/h[4];
716 r[1] = h[0] - (cs - h[7])/h[4];
717 r[2] = h[1] + h[3]*t;
718
719 g[0] = cs; g[1]=sn; g[2]=h[3];
720
721 gg[0]=-h[4]*sn; gg[1]=h[4]*cs; gg[2]=0.;
722}
723
724Double_t AliExternalTrackParam::GetDCA(const AliExternalTrackParam *p,
725Double_t b, Double_t &xthis, Double_t &xp) const {
726 //------------------------------------------------------------
727 // Returns the (weighed !) distance of closest approach between
728 // this track and the track "p".
729 // Other returned values:
730 // xthis, xt - coordinates of tracks' reference planes at the DCA
731 //-----------------------------------------------------------
732 Double_t dy2=GetSigmaY2() + p->GetSigmaY2();
733 Double_t dz2=GetSigmaZ2() + p->GetSigmaZ2();
734 Double_t dx2=dy2;
735
736 //dx2=dy2=dz2=1.;
737
738 Double_t p1[8]; GetHelixParameters(p1,b);
739 p1[6]=TMath::Sin(p1[2]); p1[7]=TMath::Cos(p1[2]);
740 Double_t p2[8]; p->GetHelixParameters(p2,b);
741 p2[6]=TMath::Sin(p2[2]); p2[7]=TMath::Cos(p2[2]);
742
743
744 Double_t r1[3],g1[3],gg1[3]; Double_t t1=0.;
745 Evaluate(p1,t1,r1,g1,gg1);
746 Double_t r2[3],g2[3],gg2[3]; Double_t t2=0.;
747 Evaluate(p2,t2,r2,g2,gg2);
748
749 Double_t dx=r2[0]-r1[0], dy=r2[1]-r1[1], dz=r2[2]-r1[2];
750 Double_t dm=dx*dx/dx2 + dy*dy/dy2 + dz*dz/dz2;
751
752 Int_t max=27;
753 while (max--) {
754 Double_t gt1=-(dx*g1[0]/dx2 + dy*g1[1]/dy2 + dz*g1[2]/dz2);
755 Double_t gt2=+(dx*g2[0]/dx2 + dy*g2[1]/dy2 + dz*g2[2]/dz2);
756 Double_t h11=(g1[0]*g1[0] - dx*gg1[0])/dx2 +
757 (g1[1]*g1[1] - dy*gg1[1])/dy2 +
758 (g1[2]*g1[2] - dz*gg1[2])/dz2;
759 Double_t h22=(g2[0]*g2[0] + dx*gg2[0])/dx2 +
760 (g2[1]*g2[1] + dy*gg2[1])/dy2 +
761 (g2[2]*g2[2] + dz*gg2[2])/dz2;
762 Double_t h12=-(g1[0]*g2[0]/dx2 + g1[1]*g2[1]/dy2 + g1[2]*g2[2]/dz2);
763
764 Double_t det=h11*h22-h12*h12;
765
766 Double_t dt1,dt2;
767 if (TMath::Abs(det)<1.e-33) {
768 //(quasi)singular Hessian
769 dt1=-gt1; dt2=-gt2;
770 } else {
771 dt1=-(gt1*h22 - gt2*h12)/det;
772 dt2=-(h11*gt2 - h12*gt1)/det;
773 }
774
775 if ((dt1*gt1+dt2*gt2)>0) {dt1=-dt1; dt2=-dt2;}
776
777 //check delta(phase1) ?
778 //check delta(phase2) ?
779
780 if (TMath::Abs(dt1)/(TMath::Abs(t1)+1.e-3) < 1.e-4)
781 if (TMath::Abs(dt2)/(TMath::Abs(t2)+1.e-3) < 1.e-4) {
782 if ((gt1*gt1+gt2*gt2) > 1.e-4/dy2/dy2)
783 AliWarning(" stopped at not a stationary point !");
784 Double_t lmb=h11+h22; lmb=lmb-TMath::Sqrt(lmb*lmb-4*det);
785 if (lmb < 0.)
786 AliWarning(" stopped at not a minimum !");
787 break;
788 }
789
790 Double_t dd=dm;
791 for (Int_t div=1 ; ; div*=2) {
792 Evaluate(p1,t1+dt1,r1,g1,gg1);
793 Evaluate(p2,t2+dt2,r2,g2,gg2);
794 dx=r2[0]-r1[0]; dy=r2[1]-r1[1]; dz=r2[2]-r1[2];
795 dd=dx*dx/dx2 + dy*dy/dy2 + dz*dz/dz2;
796 if (dd<dm) break;
797 dt1*=0.5; dt2*=0.5;
798 if (div>512) {
799 AliWarning(" overshoot !"); break;
800 }
801 }
802 dm=dd;
803
804 t1+=dt1;
805 t2+=dt2;
806
807 }
808
809 if (max<=0) AliWarning(" too many iterations !");
810
811 Double_t cs=TMath::Cos(GetAlpha());
812 Double_t sn=TMath::Sin(GetAlpha());
813 xthis=r1[0]*cs + r1[1]*sn;
814
815 cs=TMath::Cos(p->GetAlpha());
816 sn=TMath::Sin(p->GetAlpha());
817 xp=r2[0]*cs + r2[1]*sn;
818
819 return TMath::Sqrt(dm*TMath::Sqrt(dy2*dz2));
820}
821
822Double_t AliExternalTrackParam::
823PropagateToDCA(AliExternalTrackParam *p, Double_t b) {
824 //--------------------------------------------------------------
825 // Propagates this track and the argument track to the position of the
826 // distance of closest approach.
827 // Returns the (weighed !) distance of closest approach.
828 //--------------------------------------------------------------
829 Double_t xthis,xp;
830 Double_t dca=GetDCA(p,b,xthis,xp);
831
832 if (!PropagateTo(xthis,b)) {
833 //AliWarning(" propagation failed !");
834 return 1e+33;
835 }
836
837 if (!p->PropagateTo(xp,b)) {
838 //AliWarning(" propagation failed !";
839 return 1e+33;
840 }
841
842 return dca;
843}
844
845
846
f76701bf 847
848Bool_t AliExternalTrackParam::PropagateToDCA(const AliESDVertex *vtx, Double_t b, Double_t maxd){
849 //
850 // Try to relate this track to the vertex "vtx",
851 // if the (rough) transverse impact parameter is not bigger then "maxd".
852 // Magnetic field is "b" (kG).
853 //
854 // a) The track gets extapolated to the DCA to the vertex.
855 // b) The impact parameters and their covariance matrix are calculated.
856 //
857 // In the case of success, the returned value is kTRUE
858 // (otherwise, it's kFALSE)
859 //
860 Double_t alpha=GetAlpha();
861 Double_t sn=TMath::Sin(alpha), cs=TMath::Cos(alpha);
862 Double_t x=GetX(), y=GetParameter()[0], snp=GetParameter()[2];
863 Double_t xv= vtx->GetXv()*cs + vtx->GetYv()*sn;
29fbcc93 864 Double_t yv=-vtx->GetXv()*sn + vtx->GetYv()*cs;
f76701bf 865 x-=xv; y-=yv;
866
867 //Estimate the impact parameter neglecting the track curvature
868 Double_t d=TMath::Abs(x*snp - y*TMath::Sqrt(1.- snp*snp));
869 if (d > maxd) return kFALSE;
870
871 //Propagate to the DCA
872 Double_t crv=0.299792458e-3*b*GetParameter()[4];
873 Double_t tgfv=-(crv*x - snp)/(crv*y + TMath::Sqrt(1.-snp*snp));
874 sn=tgfv/TMath::Sqrt(1.+ tgfv*tgfv); cs=TMath::Sqrt(1.- sn*sn);
875
876 x = xv*cs + yv*sn;
877 yv=-xv*sn + yv*cs; xv=x;
878
879 if (!Propagate(alpha+TMath::ASin(sn),xv,b)) return kFALSE;
29fbcc93 880 return kTRUE;
f76701bf 881}
882
883
884
885
c9ec41e8 886Bool_t Local2GlobalMomentum(Double_t p[3],Double_t alpha) {
887 //----------------------------------------------------------------
888 // This function performs local->global transformation of the
889 // track momentum.
890 // When called, the arguments are:
891 // p[0] = 1/pt of the track;
892 // p[1] = sine of local azim. angle of the track momentum;
893 // p[2] = tangent of the track momentum dip angle;
894 // alpha - rotation angle.
895 // The result is returned as:
896 // p[0] = px
897 // p[1] = py
898 // p[2] = pz
899 // Results for (nearly) straight tracks are meaningless !
900 //----------------------------------------------------------------
e421f556 901 if (TMath::Abs(p[0])<=kAlmost0) return kFALSE;
49d13e89 902 if (TMath::Abs(p[1])> kAlmost1) return kFALSE;
c9ec41e8 903
904 Double_t pt=1./TMath::Abs(p[0]);
905 Double_t cs=TMath::Cos(alpha), sn=TMath::Sin(alpha);
906 Double_t r=TMath::Sqrt(1 - p[1]*p[1]);
907 p[0]=pt*(r*cs - p[1]*sn); p[1]=pt*(p[1]*cs + r*sn); p[2]=pt*p[2];
a5e407e9 908
909 return kTRUE;
910}
911
c9ec41e8 912Bool_t Local2GlobalPosition(Double_t r[3],Double_t alpha) {
913 //----------------------------------------------------------------
914 // This function performs local->global transformation of the
915 // track position.
916 // When called, the arguments are:
917 // r[0] = local x
918 // r[1] = local y
919 // r[2] = local z
920 // alpha - rotation angle.
921 // The result is returned as:
922 // r[0] = global x
923 // r[1] = global y
924 // r[2] = global z
925 //----------------------------------------------------------------
926 Double_t cs=TMath::Cos(alpha), sn=TMath::Sin(alpha), x=r[0];
927 r[0]=x*cs - r[1]*sn; r[1]=x*sn + r[1]*cs;
a5e407e9 928
a5e407e9 929 return kTRUE;
51ad6848 930}
931
b1149664 932void AliExternalTrackParam::GetDirection(Double_t d[3]) const {
933 //----------------------------------------------------------------
934 // This function returns a unit vector along the track direction
935 // in the global coordinate system.
936 //----------------------------------------------------------------
937 Double_t cs=TMath::Cos(fAlpha), sn=TMath::Sin(fAlpha);
938 Double_t snp=fP[2];
92934324 939 Double_t csp =TMath::Sqrt((1.- snp)*(1.+snp));
b1149664 940 Double_t norm=TMath::Sqrt(1.+ fP[3]*fP[3]);
941 d[0]=(csp*cs - snp*sn)/norm;
942 d[1]=(snp*cs + csp*sn)/norm;
943 d[2]=fP[3]/norm;
944}
945
c9ec41e8 946Bool_t AliExternalTrackParam::GetPxPyPz(Double_t *p) const {
947 //---------------------------------------------------------------------
948 // This function returns the global track momentum components
949 // Results for (nearly) straight tracks are meaningless !
950 //---------------------------------------------------------------------
951 p[0]=fP[4]; p[1]=fP[2]; p[2]=fP[3];
952 return Local2GlobalMomentum(p,fAlpha);
953}
a5e407e9 954
c9ec41e8 955Bool_t AliExternalTrackParam::GetXYZ(Double_t *r) const {
956 //---------------------------------------------------------------------
957 // This function returns the global track position
958 //---------------------------------------------------------------------
959 r[0]=fX; r[1]=fP[0]; r[2]=fP[1];
960 return Local2GlobalPosition(r,fAlpha);
51ad6848 961}
962
c9ec41e8 963Bool_t AliExternalTrackParam::GetCovarianceXYZPxPyPz(Double_t cv[21]) const {
964 //---------------------------------------------------------------------
965 // This function returns the global covariance matrix of the track params
966 //
967 // Cov(x,x) ... : cv[0]
968 // Cov(y,x) ... : cv[1] cv[2]
969 // Cov(z,x) ... : cv[3] cv[4] cv[5]
970 // Cov(px,x)... : cv[6] cv[7] cv[8] cv[9]
971 // Cov(py,x)... : cv[10] cv[11] cv[12] cv[13] cv[14]
972 // Cov(pz,x)... : cv[15] cv[16] cv[17] cv[18] cv[19] cv[20]
a5e407e9 973 //
c9ec41e8 974 // Results for (nearly) straight tracks are meaningless !
975 //---------------------------------------------------------------------
e421f556 976 if (TMath::Abs(fP[4])<=kAlmost0) {
c9ec41e8 977 for (Int_t i=0; i<21; i++) cv[i]=0.;
978 return kFALSE;
a5e407e9 979 }
49d13e89 980 if (TMath::Abs(fP[2]) > kAlmost1) {
c9ec41e8 981 for (Int_t i=0; i<21; i++) cv[i]=0.;
982 return kFALSE;
983 }
984 Double_t pt=1./TMath::Abs(fP[4]);
985 Double_t cs=TMath::Cos(fAlpha), sn=TMath::Sin(fAlpha);
92934324 986 Double_t r=TMath::Sqrt((1.-fP[2])*(1.+fP[2]));
c9ec41e8 987
988 Double_t m00=-sn, m10=cs;
989 Double_t m23=-pt*(sn + fP[2]*cs/r), m43=-pt*pt*(r*cs - fP[2]*sn);
990 Double_t m24= pt*(cs - fP[2]*sn/r), m44=-pt*pt*(r*sn + fP[2]*cs);
991 Double_t m35=pt, m45=-pt*pt*fP[3];
992
854d5d49 993 m43*=GetSign();
994 m44*=GetSign();
995 m45*=GetSign();
996
c9ec41e8 997 cv[0 ] = fC[0]*m00*m00;
998 cv[1 ] = fC[0]*m00*m10;
999 cv[2 ] = fC[0]*m10*m10;
1000 cv[3 ] = fC[1]*m00;
1001 cv[4 ] = fC[1]*m10;
1002 cv[5 ] = fC[2];
1003 cv[6 ] = m00*(fC[3]*m23 + fC[10]*m43);
1004 cv[7 ] = m10*(fC[3]*m23 + fC[10]*m43);
1005 cv[8 ] = fC[4]*m23 + fC[11]*m43;
1006 cv[9 ] = m23*(fC[5]*m23 + fC[12]*m43) + m43*(fC[12]*m23 + fC[14]*m43);
1007 cv[10] = m00*(fC[3]*m24 + fC[10]*m44);
1008 cv[11] = m10*(fC[3]*m24 + fC[10]*m44);
1009 cv[12] = fC[4]*m24 + fC[11]*m44;
1010 cv[13] = m23*(fC[5]*m24 + fC[12]*m44) + m43*(fC[12]*m24 + fC[14]*m44);
1011 cv[14] = m24*(fC[5]*m24 + fC[12]*m44) + m44*(fC[12]*m24 + fC[14]*m44);
1012 cv[15] = m00*(fC[6]*m35 + fC[10]*m45);
1013 cv[16] = m10*(fC[6]*m35 + fC[10]*m45);
1014 cv[17] = fC[7]*m35 + fC[11]*m45;
1015 cv[18] = m23*(fC[8]*m35 + fC[12]*m45) + m43*(fC[13]*m35 + fC[14]*m45);
1016 cv[19] = m24*(fC[8]*m35 + fC[12]*m45) + m44*(fC[13]*m35 + fC[14]*m45);
1017 cv[20] = m35*(fC[9]*m35 + fC[13]*m45) + m45*(fC[13]*m35 + fC[14]*m45);
51ad6848 1018
c9ec41e8 1019 return kTRUE;
51ad6848 1020}
1021
51ad6848 1022
c9ec41e8 1023Bool_t
1024AliExternalTrackParam::GetPxPyPzAt(Double_t x, Double_t b, Double_t *p) const {
1025 //---------------------------------------------------------------------
1026 // This function returns the global track momentum extrapolated to
1027 // the radial position "x" (cm) in the magnetic field "b" (kG)
1028 //---------------------------------------------------------------------
c9ec41e8 1029 p[0]=fP[4];
1530f89c 1030 p[1]=fP[2]+(x-fX)*GetC(b);
c9ec41e8 1031 p[2]=fP[3];
1032 return Local2GlobalMomentum(p,fAlpha);
51ad6848 1033}
1034
c9ec41e8 1035Bool_t
7cf7bb6c 1036AliExternalTrackParam::GetYAt(Double_t x, Double_t b, Double_t &y) const {
1037 //---------------------------------------------------------------------
1038 // This function returns the local Y-coordinate of the intersection
1039 // point between this track and the reference plane "x" (cm).
1040 // Magnetic field "b" (kG)
1041 //---------------------------------------------------------------------
1042 Double_t dx=x-fX;
1043 if(TMath::Abs(dx)<=kAlmost0) {y=fP[0]; return kTRUE;}
1044
1530f89c 1045 Double_t f1=fP[2], f2=f1 + dx*GetC(b);
7cf7bb6c 1046
1047 if (TMath::Abs(f1) >= kAlmost1) return kFALSE;
1048 if (TMath::Abs(f2) >= kAlmost1) return kFALSE;
1049
1050 Double_t r1=TMath::Sqrt(1.- f1*f1), r2=TMath::Sqrt(1.- f2*f2);
1051 y = fP[0] + dx*(f1+f2)/(r1+r2);
1052 return kTRUE;
1053}
1054
1055Bool_t
6c94f330 1056AliExternalTrackParam::GetZAt(Double_t x, Double_t b, Double_t &z) const {
1057 //---------------------------------------------------------------------
1058 // This function returns the local Z-coordinate of the intersection
1059 // point between this track and the reference plane "x" (cm).
1060 // Magnetic field "b" (kG)
1061 //---------------------------------------------------------------------
1062 Double_t dx=x-fX;
1063 if(TMath::Abs(dx)<=kAlmost0) {z=fP[1]; return kTRUE;}
1064
1065 Double_t f1=fP[2], f2=f1 + dx*fP[4]*b*kB2C;
1066
1067 if (TMath::Abs(f1) >= kAlmost1) return kFALSE;
1068 if (TMath::Abs(f2) >= kAlmost1) return kFALSE;
1069
1070 Double_t r1=sqrt(1.- f1*f1), r2=sqrt(1.- f2*f2);
1071 z = fP[1] + dx*(r2 + f2*(f1+f2)/(r1+r2))*fP[3]; // Many thanks to P.Hristov !
1072 return kTRUE;
1073}
1074
1075Bool_t
c9ec41e8 1076AliExternalTrackParam::GetXYZAt(Double_t x, Double_t b, Double_t *r) const {
1077 //---------------------------------------------------------------------
1078 // This function returns the global track position extrapolated to
1079 // the radial position "x" (cm) in the magnetic field "b" (kG)
1080 //---------------------------------------------------------------------
c9ec41e8 1081 Double_t dx=x-fX;
e421f556 1082 if(TMath::Abs(dx)<=kAlmost0) return GetXYZ(r);
1083
1530f89c 1084 Double_t f1=fP[2], f2=f1 + dx*GetC(b);
c9ec41e8 1085
e421f556 1086 if (TMath::Abs(f1) >= kAlmost1) return kFALSE;
49d13e89 1087 if (TMath::Abs(f2) >= kAlmost1) return kFALSE;
c9ec41e8 1088
1089 Double_t r1=TMath::Sqrt(1.- f1*f1), r2=TMath::Sqrt(1.- f2*f2);
1090 r[0] = x;
1091 r[1] = fP[0] + dx*(f1+f2)/(r1+r2);
6c94f330 1092 r[2] = fP[1] + dx*(f1+f2)/(f1*r2 + f2*r1)*fP[3];
c9ec41e8 1093 return Local2GlobalPosition(r,fAlpha);
51ad6848 1094}
1095
edc97986 1096//_____________________________________________________________________________
51ad6848 1097void AliExternalTrackParam::Print(Option_t* /*option*/) const
1098{
1099// print the parameters and the covariance matrix
1100
1101 printf("AliExternalTrackParam: x = %-12g alpha = %-12g\n", fX, fAlpha);
1102 printf(" parameters: %12g %12g %12g %12g %12g\n",
c9ec41e8 1103 fP[0], fP[1], fP[2], fP[3], fP[4]);
1104 printf(" covariance: %12g\n", fC[0]);
1105 printf(" %12g %12g\n", fC[1], fC[2]);
1106 printf(" %12g %12g %12g\n", fC[3], fC[4], fC[5]);
51ad6848 1107 printf(" %12g %12g %12g %12g\n",
c9ec41e8 1108 fC[6], fC[7], fC[8], fC[9]);
51ad6848 1109 printf(" %12g %12g %12g %12g %12g\n",
c9ec41e8 1110 fC[10], fC[11], fC[12], fC[13], fC[14]);
51ad6848 1111}
5b77d93c 1112
c194ba83 1113Double_t AliExternalTrackParam::GetSnpAt(Double_t x,Double_t b) const {
1114 //
1115 // Get sinus at given x
1116 //
1530f89c 1117 Double_t crv=GetC(b);
c194ba83 1118 if (TMath::Abs(b) < kAlmost0Field) crv=0.;
1119 Double_t dx = x-fX;
1120 Double_t res = fP[2]+dx*crv;
1121 return res;
1122}