]>
Commit | Line | Data |
---|---|---|
7f572c00 | 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 | // Implementation of the AliHelix class | |
20 | // Origin: Marian Ivanov, CERN, marian.ivanov@cern.ch | |
21 | //------------------------------------------------------------------------- | |
22 | ||
23 | ||
24 | #include "AliHelix.h" | |
25 | #include "AliKalmanTrack.h" | |
26 | #include "TMath.h" | |
27 | ClassImp(AliHelix) | |
28 | ||
29 | ||
30 | //_______________________________________________________________________ | |
31 | AliHelix::AliHelix() | |
32 | { | |
33 | // | |
34 | // Default constructor | |
35 | // | |
36 | for (Int_t i =0;i<9;i++) fHelix[i]=0; | |
37 | } | |
38 | ||
39 | //_______________________________________________________________________ | |
176aff27 | 40 | AliHelix::AliHelix(const AliHelix &t):TObject(t){ |
7f572c00 | 41 | // |
42 | // | |
43 | for (Int_t i=0;i<9;i++) | |
44 | fHelix[i]=t.fHelix[i]; | |
45 | } | |
46 | ||
47 | AliHelix::AliHelix(const AliKalmanTrack &t) | |
48 | { | |
49 | // | |
50 | // | |
51 | Double_t alpha,x,cs,sn; | |
52 | t.GetExternalParameters(x,fHelix); | |
53 | alpha=t.GetAlpha(); | |
54 | // | |
55 | //circle parameters | |
56 | fHelix[4]=fHelix[4]/t.GetConvConst(); // C | |
57 | cs=TMath::Cos(alpha); sn=TMath::Sin(alpha); | |
58 | ||
59 | Double_t xc, yc, rc; | |
60 | rc = 1/fHelix[4]; | |
61 | xc = x-fHelix[2]*rc; | |
62 | yc = fHelix[0]+TMath::Sqrt(1-(x-xc)*(x-xc)*fHelix[4]*fHelix[4])/fHelix[4]; | |
63 | ||
64 | fHelix[6] = xc*cs - yc*sn; | |
65 | fHelix[7] = xc*sn + yc*cs; | |
66 | fHelix[8] = TMath::Abs(rc); | |
67 | // | |
68 | // | |
69 | fHelix[5]=x*cs - fHelix[0]*sn; // x0 | |
70 | fHelix[0]=x*sn + fHelix[0]*cs; // y0 | |
71 | //fHelix[1]= // z0 | |
72 | fHelix[2]=TMath::ASin(fHelix[2]) + alpha; // phi0 | |
73 | //fHelix[3]= // tgl | |
74 | // | |
75 | // | |
76 | fHelix[5] = fHelix[6]; | |
77 | fHelix[0] = fHelix[7]; | |
78 | //fHelix[5]-=TMath::Sin(fHelix[2])/fHelix[4]; | |
79 | //fHelix[0]+=TMath::Cos(fHelix[2])/fHelix[4]; | |
80 | } | |
81 | ||
82 | AliHelix::AliHelix(Double_t x[3], Double_t p[3], Double_t charge, Double_t conversion) | |
83 | { | |
84 | // | |
85 | // | |
86 | // | |
87 | Double_t pt = TMath::Sqrt(p[0]*p[0]+p[1]*p[1]); | |
88 | if (TMath::Abs(conversion)<0.00000001) | |
89 | conversion = AliKalmanTrack::GetConvConst(); | |
90 | // | |
91 | // | |
92 | fHelix[4] = charge/(conversion*pt); // C | |
93 | fHelix[3] = p[2]/pt; // tgl | |
94 | // | |
95 | Double_t xc, yc, rc; | |
96 | rc = 1/fHelix[4]; | |
97 | xc = x[0] -rc*p[1]/pt; | |
98 | yc = x[1] +rc*p[0]/pt; | |
99 | // | |
100 | fHelix[5] = x[0]; // x0 | |
101 | fHelix[0] = x[1]; // y0 | |
102 | fHelix[1] = x[2]; // z0 | |
103 | // | |
104 | fHelix[6] = xc; | |
105 | fHelix[7] = yc; | |
106 | fHelix[8] = TMath::Abs(rc); | |
107 | // | |
108 | fHelix[5]=xc; | |
109 | fHelix[0]=yc; | |
110 | // | |
111 | if (TMath::Abs(p[1])<TMath::Abs(p[0])){ | |
112 | fHelix[2]=TMath::ASin(p[1]/pt); | |
113 | if (charge*yc<charge*x[1]) fHelix[2] = TMath::Pi()-fHelix[2]; | |
114 | } | |
115 | else{ | |
116 | fHelix[2]=TMath::ACos(p[0]/pt); | |
117 | if (charge*xc>charge*x[0]) fHelix[2] = -fHelix[2]; | |
118 | } | |
119 | ||
120 | } | |
121 | ||
122 | void AliHelix::GetMomentum(Double_t phase, Double_t p[4],Double_t conversion) | |
123 | { | |
124 | // return momentum at given phase | |
125 | Double_t x[3],g[3],gg[3]; | |
126 | Evaluate(phase,x,g,gg); | |
127 | if (TMath::Abs(conversion)<0.0001) conversion = AliKalmanTrack::GetConvConst(); | |
128 | Double_t mt = TMath::Sqrt(g[0]*g[0]+g[1]*g[1]); | |
129 | p[0] = fHelix[8]*g[0]/(mt*conversion); | |
130 | p[1] = fHelix[8]*g[1]/(mt*conversion); | |
131 | p[2] = fHelix[8]*g[2]/(mt*conversion); | |
132 | } | |
133 | ||
134 | void AliHelix::GetAngle(Double_t t1, AliHelix &h, Double_t t2, Double_t angle[3]) | |
135 | { | |
136 | // | |
137 | // | |
138 | // | |
139 | Double_t x1[3],g1[3],gg1[3]; | |
140 | Double_t x2[3],g2[3],gg2[3]; | |
141 | Evaluate(t1,x1,g1,gg1); | |
142 | h.Evaluate(t2,x2,g2,gg2); | |
143 | ||
144 | // | |
145 | Double_t norm1r = g1[0]*g1[0]+g1[1]*g1[1]; | |
146 | Double_t norm1 = TMath::Sqrt(norm1r+g1[2]*g1[2]); | |
147 | norm1r = TMath::Sqrt(norm1r); | |
148 | // | |
149 | Double_t norm2r = g2[0]*g2[0]+g2[1]*g2[1]; | |
150 | Double_t norm2 = TMath::Sqrt(norm2r+g2[2]*g2[2]); | |
151 | norm2r = TMath::Sqrt(norm2r); | |
152 | // | |
153 | angle[0] = TMath::ACos((g1[0]*g2[0]+g1[1]*g2[1])/(norm1r*norm2r)); // angle in phi projection | |
154 | angle[1] = TMath::ACos(((norm1r*norm2r)+g1[2]*g2[2])/(norm1*norm2)); // angle in rz projection | |
155 | angle[2] = TMath::ACos((g1[0]*g2[0]+g1[1]*g2[1]+g1[2]*g2[2])/(norm1*norm2)); //3D angle | |
156 | ||
157 | ||
158 | ||
159 | ||
160 | } | |
161 | ||
162 | ||
163 | void AliHelix::Evaluate(Double_t t, | |
164 | Double_t r[3], //radius vector | |
165 | Double_t g[3], //first defivatives | |
166 | Double_t gg[3]) //second derivatives | |
167 | { | |
168 | //-------------------------------------------------------------------- | |
169 | // Calculate position of a point on a track and some derivatives at given phase | |
170 | //-------------------------------------------------------------------- | |
171 | Double_t phase=fHelix[4]*t+fHelix[2]; | |
172 | Double_t sn=TMath::Sin(phase), cs=TMath::Cos(phase); | |
173 | ||
174 | //r[0] = fHelix[5] + (sn - fHelix[6])/fHelix[4]; | |
175 | //r[1] = fHelix[0] - (cs - fHelix[7])/fHelix[4]; | |
176 | r[0] = fHelix[5] + sn/fHelix[4]; | |
177 | r[1] = fHelix[0] - cs/fHelix[4]; | |
178 | r[2] = fHelix[1] + fHelix[3]*t; | |
179 | ||
180 | g[0] = cs; g[1]=sn; g[2]=fHelix[3]; | |
181 | ||
182 | gg[0]=-fHelix[4]*sn; gg[1]=fHelix[4]*cs; gg[2]=0.; | |
183 | } | |
184 | ||
185 | Double_t AliHelix::GetPhase(Double_t x, Double_t y ) | |
186 | ||
187 | { | |
188 | // | |
189 | //calculate helix param at given x,y point | |
190 | // | |
191 | Double_t phase = (x-fHelix[5])*fHelix[4]; | |
192 | if (TMath::Abs(phase)>=1) | |
193 | phase = TMath::Sign(0.99999999999,phase); | |
194 | phase = TMath::ASin(phase); | |
195 | ||
196 | if ( ( ( fHelix[0]-y)*fHelix[4]) < 0.) { | |
197 | if (phase>0) | |
198 | phase = TMath::Pi()-phase; | |
199 | else | |
200 | phase = -(TMath::Pi()+phase); | |
201 | } | |
202 | if ( (phase-fHelix[2])>TMath::Pi()) phase = phase-2.*TMath::Pi(); | |
203 | if ( (phase-fHelix[2])<-TMath::Pi()) phase = phase+2.*TMath::Pi(); | |
204 | ||
205 | Double_t t = (phase-fHelix[2])/fHelix[4]; | |
206 | ||
207 | // Double_t r[3]; | |
208 | //Evaluate(t,r); | |
209 | //if ( (TMath::Abs(r[0]-x)>0.01) || (TMath::Abs(r[1]-y)>0.01)){ | |
210 | // Double_t phase = (x-fHelix[5])*fHelix[4]; | |
211 | // printf("problem\n"); | |
212 | //} | |
213 | return t; | |
214 | } | |
215 | ||
176aff27 | 216 | Int_t AliHelix::GetPhase(Double_t /*r0*/, Double_t * /*t[2]*/) |
7f572c00 | 217 | { |
218 | // | |
219 | //calculate helix param at given r point - return nearest point () | |
220 | // | |
221 | // not implemented yet | |
222 | ||
223 | ||
224 | return 0; | |
225 | } | |
226 | ||
227 | ||
228 | Double_t AliHelix::GetPhaseZ(Double_t z0) | |
229 | { | |
230 | // | |
231 | // | |
232 | return (z0-fHelix[1])/fHelix[3]; | |
233 | } | |
234 | ||
235 | ||
236 | Int_t AliHelix::GetRPHIintersections(AliHelix &h, Double_t phase[2][2], Double_t ri[2], Double_t cut) | |
237 | { | |
238 | //-------------------------------------------------------------------- | |
239 | // This function returns phase vectors with intesection between helix (0, 1 or 2) | |
240 | // in x-y plane projection | |
241 | //-------------------------------------------------------------------- | |
242 | // | |
243 | // Double_t * c1 = &fHelix[6]; | |
244 | //Double_t * c2 = &(h.fHelix[6]); | |
245 | // Double_t c1[3] = {fHelix[5],fHelix[0],fHelix[8]}; | |
246 | Double_t c1[3] = {0,0,fHelix[8]}; | |
247 | Double_t c2[3] = {h.fHelix[5]-fHelix[5],h.fHelix[0]-fHelix[0],h.fHelix[8]}; | |
248 | ||
249 | Double_t d = TMath::Sqrt(c2[0]*c2[0]+c2[1]*c2[1]); | |
250 | // | |
251 | Double_t x0[2]; | |
252 | Double_t y0[2]; | |
253 | // | |
254 | if ( d>=(c1[2]+c2[2])){ | |
255 | if (d>=(c1[2]+c2[2]+cut)) return 0; | |
256 | x0[0] = (d+c1[2]-c2[2])*c2[0]/(2*d)+ fHelix[5]; | |
257 | y0[0] = (d+c1[2]-c2[2])*c2[1]/(2*d)+ fHelix[0]; | |
258 | return 0; | |
259 | phase[0][0] = GetPhase(x0[0],y0[0]); | |
260 | phase[0][1] = h.GetPhase(x0[0],y0[0]); | |
261 | ri[0] = x0[0]*x0[0]+y0[0]*y0[0]; | |
262 | return 1; | |
263 | } | |
264 | if ( (d+c2[2])<c1[2]){ | |
265 | if ( (d+c2[2])+cut<c1[2]) return 0; | |
266 | // | |
267 | Double_t xx = c2[0]+ c2[0]*c2[2]/d+ fHelix[5]; | |
268 | Double_t yy = c2[1]+ c2[1]*c2[2]/d+ fHelix[0]; | |
269 | phase[0][1] = h.GetPhase(xx,yy); | |
270 | // | |
271 | Double_t xx2 = c2[0]*c1[2]/d+ fHelix[5]; | |
272 | Double_t yy2 = c2[1]*c1[2]/d+ fHelix[0]; | |
273 | phase[0][0] = GetPhase(xx2,yy2); | |
274 | ri[0] = xx*xx+yy*yy; | |
275 | return 1; | |
276 | } | |
277 | ||
278 | if ( (d+c1[2])<c2[2]){ | |
279 | if ( (d+c1[2])+cut<c2[2]) return 0; | |
280 | // | |
281 | Double_t xx = -c2[0]*c1[2]/d+ fHelix[5]; | |
282 | Double_t yy = -c2[1]*c1[2]/d+ fHelix[0]; | |
283 | phase[0][1] = GetPhase(xx,yy); | |
284 | // | |
285 | Double_t xx2 = c2[0]- c2[0]*c2[2]/d+ fHelix[5]; | |
286 | Double_t yy2 = c2[1]- c2[1]*c2[2]/d+ fHelix[0]; | |
287 | phase[0][0] = h.GetPhase(xx2,yy2); | |
288 | ri[0] = xx*xx+yy*yy; | |
289 | return 1; | |
290 | } | |
291 | ||
292 | Double_t d1 = (d*d+c1[2]*c1[2]-c2[2]*c2[2])/(2.*d); | |
293 | Double_t v1 = c1[2]*c1[2]-d1*d1; | |
294 | if (v1<0) return 0; | |
295 | v1 = TMath::Sqrt(v1); | |
296 | // | |
297 | x0[0] = (c2[0]*d1+c2[1]*v1)/d + fHelix[5]; | |
298 | y0[0] = (c2[1]*d1-c2[0]*v1)/d + fHelix[0]; | |
299 | // | |
300 | x0[1] = (c2[0]*d1-c2[1]*v1)/d + fHelix[5]; | |
301 | y0[1] = (c2[1]*d1+c2[0]*v1)/d + fHelix[0]; | |
302 | // | |
303 | for (Int_t i=0;i<2;i++){ | |
304 | phase[i][0] = GetPhase(x0[i],y0[i]); | |
305 | phase[i][1] = h.GetPhase(x0[i],y0[i]); | |
306 | ri[i] = x0[i]*x0[i]+y0[i]*y0[i]; | |
307 | } | |
308 | return 2; | |
309 | } | |
310 | ||
311 | /* | |
312 | ||
313 | Int_t AliHelix::GetRPHIintersections(AliHelix &h, Double_t phase[2][2], Double_t ri[2], Double_t cut) | |
314 | { | |
315 | //-------------------------------------------------------------------- | |
316 | // This function returns phase vectors with intesection between helix (0, 1 or 2) | |
317 | // in x-y plane projection | |
318 | //-------------------------------------------------------------------- | |
319 | // | |
320 | Double_t * c1 = &fHelix[6]; | |
321 | Double_t * c2 = &(h.fHelix[6]); | |
322 | Double_t d = TMath::Sqrt((c1[0]-c2[0])*(c1[0]-c2[0])+(c1[1]-c2[1])*(c1[1]-c2[1])); | |
323 | // | |
324 | Double_t x0[2]; | |
325 | Double_t y0[2]; | |
326 | // | |
327 | if ( d>=(c1[2]+c2[2])){ | |
328 | if (d>=(c1[2]+c2[2]+cut)) return 0; | |
329 | x0[0] = c1[0]+ (d+c1[2]-c2[2])*(c2[0]-c1[0])/(2*d); | |
330 | y0[0] = c1[1]+ (d+c1[2]-c2[2])*(c2[1]-c1[1])/(2*d); | |
331 | return 0; | |
332 | phase[0][0] = GetPhase(x0[0],y0[0]); | |
333 | phase[0][1] = h.GetPhase(x0[0],y0[0]); | |
334 | ri[0] = x0[0]*x0[0]+y0[0]*y0[0]; | |
335 | return 1; | |
336 | } | |
337 | if ( (d+c2[2])<c1[2]){ | |
338 | if ( (d+c2[2])+cut<c1[2]) return 0; | |
339 | // | |
340 | Double_t xx = c2[0]+ (c2[0]-c1[0])*c2[2]/d; | |
341 | Double_t yy = c2[1]+ (c2[1]-c1[1])*c2[2]/d; | |
342 | phase[0][1] = h.GetPhase(xx,yy); | |
343 | // | |
344 | Double_t xx2 = c1[0]- (c1[0]-c2[0])*c1[2]/d; | |
345 | Double_t yy2 = c1[1]- (c1[1]-c2[1])*c1[2]/d; | |
346 | phase[0][0] = GetPhase(xx2,yy2); | |
347 | //if ( (TMath::Abs(xx2-xx)>cut)||(TMath::Abs(yy2-yy)>cut)){ | |
348 | // printf("problem\n"); | |
349 | //} | |
350 | ri[0] = xx*xx+yy*yy; | |
351 | return 1; | |
352 | } | |
353 | ||
354 | if ( (d+c1[2])<c2[2]){ | |
355 | if ( (d+c1[2])+cut<c2[2]) return 0; | |
356 | // | |
357 | Double_t xx = c1[0]+ (c1[0]-c2[0])*c1[2]/d; | |
358 | Double_t yy = c1[1]+ (c1[1]-c2[1])*c1[2]/d; | |
359 | phase[0][1] = GetPhase(xx,yy); | |
360 | // | |
361 | Double_t xx2 = c2[0]- (c2[0]-c1[0])*c2[2]/d; | |
362 | Double_t yy2 = c2[1]- (c2[1]-c1[1])*c2[2]/d; | |
363 | phase[0][0] = h.GetPhase(xx2,yy2); | |
364 | //if ( (TMath::Abs(xx2-xx)>cut)||(TMath::Abs(yy2-yy)>cut)){ | |
365 | // printf("problem\n"); | |
366 | //} | |
367 | ri[0] = xx*xx+yy*yy; | |
368 | return 1; | |
369 | } | |
370 | ||
371 | Double_t d1 = (d*d+c1[2]*c1[2]-c2[2]*c2[2])/(2.*d); | |
372 | Double_t v1 = c1[2]*c1[2]-d1*d1; | |
373 | if (v1<0) return 0; | |
374 | v1 = TMath::Sqrt(v1); | |
375 | // | |
376 | x0[0] = c1[0]+ ((c2[0]-c1[0])*d1-(c1[1]-c2[1])*v1)/d; | |
377 | y0[0] = c1[1]+ ((c2[1]-c1[1])*d1+(c1[0]-c2[0])*v1)/d; | |
378 | // | |
379 | x0[1] = c1[0]+ ((c2[0]-c1[0])*d1+(c1[1]-c2[1])*v1)/d; | |
380 | y0[1] = c1[1]+ ((c2[1]-c1[1])*d1-(c1[0]-c2[0])*v1)/d; | |
381 | // | |
382 | for (Int_t i=0;i<2;i++){ | |
383 | phase[i][0] = GetPhase(x0[i],y0[i]); | |
384 | phase[i][1] = h.GetPhase(x0[i],y0[i]); | |
385 | ri[i] = x0[i]*x0[i]+y0[i]*y0[i]; | |
386 | } | |
387 | return 2; | |
388 | } | |
389 | */ | |
390 | ||
391 | ||
392 | Int_t AliHelix::LinearDCA(AliHelix &h, Double_t &t1, Double_t &t2, | |
393 | Double_t &R, Double_t &dist) | |
394 | { | |
395 | // | |
396 | // | |
397 | // find intersection using linear approximation | |
398 | Double_t r1[3],g1[3],gg1[3]; | |
399 | Double_t r2[3],g2[3],gg2[3]; | |
400 | // | |
401 | Evaluate(t1,r1,g1,gg1); | |
402 | h.Evaluate(t2,r2,g2,gg2); | |
403 | // | |
404 | Double_t g1_2 = g1[0]*g1[0] +g1[1]*g1[1] +g1[2]*g1[2]; | |
405 | Double_t g2_2 = g2[0]*g2[0] +g2[1]*g2[1] +g2[2]*g2[2]; | |
406 | Double_t g1x2 = g1[0]*g2[0] +g1[1]*g2[1] +g1[2]*g2[2]; | |
407 | Double_t det = g1_2*g2_2 - g1x2*g1x2; | |
408 | // | |
409 | if (TMath::Abs(det)>0){ | |
410 | // | |
411 | Double_t r1g1 = r1[0]*g1[0] +r1[1]*g1[1] +r1[2]*g1[2]; | |
412 | Double_t r2g1 = r2[0]*g1[0] +r2[1]*g1[1] +r2[2]*g1[2]; | |
413 | Double_t r1g2 = r1[0]*g2[0] +r1[1]*g2[1] +r1[2]*g2[2]; | |
414 | Double_t r2g2 = r2[0]*g2[0] +r2[1]*g2[1] +r2[2]*g2[2]; | |
415 | // | |
416 | Double_t dt = - ( g2_2*(r1g1-r2g1) - g1x2*(r1g2-r2g2)) / det; | |
417 | Double_t dp = - ( g1_2*(r2g2-r1g2) - g1x2*(r2g1-r1g1)) / det; | |
418 | // | |
419 | t1+=dt; | |
420 | t2+=dp; | |
421 | Evaluate(t1,r1); | |
422 | h.Evaluate(t2,r2); | |
423 | // | |
424 | dist = (r1[0]-r2[0])*(r1[0]-r2[0])+ | |
425 | (r1[1]-r2[1])*(r1[1]-r2[1])+ | |
426 | (r1[2]-r2[2])*(r1[2]-r2[2]); | |
427 | R = ((r1[0]+r2[0])*(r1[0]+r2[0])+(r1[1]+r2[1])*(r1[1]+r2[1]))/4.; | |
428 | } | |
429 | return 0; | |
430 | } | |
431 | ||
432 | ||
433 | ||
434 | ||
435 | /* | |
436 | Int_t AliHelix::ParabolicDCA(AliHelix&h, //helixes | |
437 | Double_t &t1, Double_t &t2, | |
438 | Double_t &R, Double_t &dist, Int_t iter) | |
439 | { | |
440 | // | |
441 | // | |
442 | // find intersection using linear fit | |
443 | Double_t r1[3],g1[3],gg1[3]; | |
444 | Double_t r2[3],g2[3],gg2[3]; | |
445 | // | |
446 | Evaluate(t1,r1,g1,gg1); | |
447 | h.Evaluate(t2,r2,g2,gg2); | |
448 | ||
449 | // | |
450 | Double_t dx2=1.; | |
451 | Double_t dy2=1.; | |
452 | Double_t dz2=1.; | |
453 | // | |
454 | Double_t dx=r2[0]-r1[0], dy=r2[1]-r1[1], dz=r2[2]-r1[2]; | |
455 | Double_t dm=dx*dx/dx2 + dy*dy/dy2 + dz*dz/dz2; | |
456 | // | |
457 | ||
458 | iter++; | |
459 | while (iter--) { | |
460 | ||
461 | Double_t gt1=-(dx*g1[0]/dx2 + dy*g1[1]/dy2 + dz*g1[2]/dz2); | |
462 | Double_t gt2=+(dx*g2[0]/dx2 + dy*g2[1]/dy2 + dz*g2[2]/dz2); | |
463 | Double_t h11=(g1[0]*g1[0] - dx*gg1[0])/dx2 + | |
464 | (g1[1]*g1[1] - dy*gg1[1])/dy2 + | |
465 | (g1[2]*g1[2] - dz*gg1[2])/dz2; | |
466 | Double_t h22=(g2[0]*g2[0] + dx*gg2[0])/dx2 + | |
467 | (g2[1]*g2[1] + dy*gg2[1])/dy2 + | |
468 | (g2[2]*g2[2] + dz*gg2[2])/dz2; | |
469 | Double_t h12=-(g1[0]*g2[0]/dx2 + g1[1]*g2[1]/dy2 + g1[2]*g2[2]/dz2); | |
470 | ||
471 | Double_t det=h11*h22-h12*h12; | |
472 | ||
473 | Double_t dt1,dt2; | |
474 | if (TMath::Abs(det)<1.e-33) { | |
475 | //(quasi)singular Hessian | |
476 | dt1=-gt1; dt2=-gt2; | |
477 | } else { | |
478 | dt1=-(gt1*h22 - gt2*h12)/det; | |
479 | dt2=-(h11*gt2 - h12*gt1)/det; | |
480 | } | |
481 | ||
482 | if ((dt1*gt1+dt2*gt2)>0) {dt1=-dt1; dt2=-dt2;} | |
483 | ||
484 | //check delta(phase1) ? | |
485 | //check delta(phase2) ? | |
486 | ||
487 | if (TMath::Abs(dt1)/(TMath::Abs(t1)+1.e-3) < 1.e-4) | |
488 | if (TMath::Abs(dt2)/(TMath::Abs(t2)+1.e-3) < 1.e-4) { | |
489 | //if ((gt1*gt1+gt2*gt2) > 1.e-4/dy2/dy2) | |
490 | // Warning("GetDCA"," stopped at not a stationary point !\n"); | |
491 | Double_t lmb=h11+h22; lmb=lmb-TMath::Sqrt(lmb*lmb-4*det); | |
492 | if (lmb < 0.) | |
493 | //Warning("GetDCA"," stopped at not a minimum !\n"); | |
494 | break; | |
495 | } | |
496 | ||
497 | Double_t dd=dm; | |
498 | for (Int_t div=1 ; ; div*=2) { | |
499 | Evaluate(t1+dt1,r1,g1,gg1); | |
500 | h.Evaluate(t2+dt2,r2,g2,gg2); | |
501 | dx=r2[0]-r1[0]; dy=r2[1]-r1[1]; dz=r2[2]-r1[2]; | |
502 | dd=dx*dx/dx2 + dy*dy/dy2 + dz*dz/dz2; | |
503 | if (dd<dm) break; | |
504 | dt1*=0.5; dt2*=0.5; | |
505 | if (div>512) { | |
506 | //Warning("GetDCA"," overshoot !\n"); | |
507 | break; | |
508 | } | |
509 | } | |
510 | dm=dd; | |
511 | ||
512 | t1+=dt1; | |
513 | t2+=dt2; | |
514 | ||
515 | } | |
516 | ||
517 | Evaluate(t1,r1,g1,gg1); | |
518 | h.Evaluate(t2,r2,g2,gg2); | |
519 | // | |
520 | dist = (r1[0]-r2[0])*(r1[0]-r2[0])+ | |
521 | (r1[1]-r2[1])*(r1[1]-r2[1])+ | |
522 | (r1[2]-r2[2])*(r1[2]-r2[2]); | |
523 | ||
524 | R = ((r1[0]+r2[0])*(r1[0]+r2[0])+(r1[1]+r2[1])*(r1[1]+r2[1]))/4; | |
525 | ||
526 | } | |
527 | */ | |
528 | ||
529 | ||
530 | ||
531 | ||
532 | ||
533 | ||
534 | Int_t AliHelix::ParabolicDCA(AliHelix&h, //helixes | |
535 | Double_t &t1, Double_t &t2, | |
536 | Double_t &R, Double_t &dist, Int_t iter) | |
537 | { | |
538 | // | |
539 | // | |
540 | // find intersection using linear fit | |
541 | Double_t r1[3],g1[3],gg1[3]; | |
542 | Double_t r2[3],g2[3],gg2[3]; | |
543 | // | |
544 | Evaluate(t1,r1,g1,gg1); | |
545 | h.Evaluate(t2,r2,g2,gg2); | |
546 | ||
547 | // | |
548 | Double_t dx2=1.; | |
549 | Double_t dy2=1.; | |
550 | Double_t dz2=1.; | |
551 | // | |
552 | Double_t dx=r2[0]-r1[0], dy=r2[1]-r1[1], dz=r2[2]-r1[2]; | |
553 | Double_t dm=dx*dx/dx2 + dy*dy/dy2 + dz*dz/dz2; | |
554 | // | |
555 | ||
556 | iter++; | |
557 | while (iter--) { | |
558 | Double_t gt1=-(dx*g1[0]/dx2 + dy*g1[1]/dy2 + dz*g1[2]/dz2); | |
559 | Double_t gt2=+(dx*g2[0]/dx2 + dy*g2[1]/dy2 + dz*g2[2]/dz2); | |
560 | ||
561 | Double_t h11=(g1[0]*g1[0] - dx*gg1[0])/dx2 + | |
562 | (g1[1]*g1[1] - dy*gg1[1])/dy2 + | |
563 | (g1[2]*g1[2] - dz*gg1[2])/dz2; | |
564 | Double_t h22=(g2[0]*g2[0] + dx*gg2[0])/dx2 + | |
565 | (g2[1]*g2[1] + dy*gg2[1])/dy2 + | |
566 | (g2[2]*g2[2] + dz*gg2[2])/dz2; | |
567 | Double_t h12=-(g1[0]*g2[0]/dx2 + g1[1]*g2[1]/dy2 + g1[2]*g2[2]/dz2); | |
568 | ||
569 | Double_t det=h11*h22-h12*h12; | |
570 | ||
571 | Double_t dt1,dt2; | |
572 | if (TMath::Abs(det)<1.e-33) { | |
573 | //(quasi)singular Hessian | |
574 | dt1=-gt1; dt2=-gt2; | |
575 | } else { | |
576 | dt1=-(gt1*h22 - gt2*h12)/det; | |
577 | dt2=-(h11*gt2 - h12*gt1)/det; | |
578 | } | |
579 | ||
580 | if ((dt1*gt1+dt2*gt2)>0) {dt1=-dt1; dt2=-dt2;} | |
581 | ||
582 | //if (TMath::Abs(dt1)/(TMath::Abs(t1)+1.e-3) < 1.e-4) | |
583 | // if (TMath::Abs(dt2)/(TMath::Abs(t2)+1.e-3) < 1.e-4) { | |
584 | // break; | |
585 | // } | |
586 | ||
587 | Double_t dd=dm; | |
588 | for (Int_t div=1 ; div<512 ; div*=2) { | |
589 | Evaluate(t1+dt1,r1,g1,gg1); | |
590 | h.Evaluate(t2+dt2,r2,g2,gg2); | |
591 | dx=r2[0]-r1[0]; dy=r2[1]-r1[1]; dz=r2[2]-r1[2]; | |
592 | dd=dx*dx/dx2 + dy*dy/dy2 + dz*dz/dz2; | |
593 | if (dd<dm) break; | |
594 | dt1*=0.5; dt2*=0.5; | |
595 | if (div==0){ | |
596 | div =1; | |
597 | } | |
598 | if (div>512) { | |
599 | break; | |
600 | } | |
601 | } | |
602 | dm=dd; | |
603 | t1+=dt1; | |
604 | t2+=dt2; | |
605 | } | |
606 | Evaluate(t1,r1,g1,gg1); | |
607 | h.Evaluate(t2,r2,g2,gg2); | |
608 | // | |
609 | dist = (r1[0]-r2[0])*(r1[0]-r2[0])+ | |
610 | (r1[1]-r2[1])*(r1[1]-r2[1])+ | |
611 | (r1[2]-r2[2])*(r1[2]-r2[2]); | |
612 | ||
613 | R = ((r1[0]+r2[0])*(r1[0]+r2[0])+(r1[1]+r2[1])*(r1[1]+r2[1]))/4; | |
614 | return 0; | |
615 | ||
616 | } | |
617 |