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source: git/external/TrackCovariance/SolTrack.cc@ d631475

Last change on this file since d631475 was ff9fb2d9, checked in by Pavel Demin <pavel.demin@…>, 5 years ago

add TrackCovariance

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File size: 16.5 KB
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1#include <iostream>
2
3#include <TString.h>
4#include <TMath.h>
5#include <TMatrixD.h>
6#include <TMatrixDSym.h>
7#include <TDecompChol.h>
8#include <TMatrixDSymEigen.h>
9
10#include "SolGeom.h"
11#include "SolTrack.h"
12
13using namespace std;
14
15SolTrack::SolTrack(Double_t *x, Double_t *p, SolGeom *G)
16{
17 fG = G;
18 // Store momentum
19 fp[0] = p[0]; fp[1] = p[1]; fp[2] = p[2];
20 Double_t px = p[0]; Double_t py = p[1]; Double_t pz = p[2];
21 fx[0] = x[0]; fx[1] = x[1]; fx[2] = x[2];
22 Double_t xx = x[0]; Double_t yy = x[1]; Double_t zz = x[2];
23 // Store parameters
24 Double_t pt = TMath::Sqrt(px*px + py*py);
25 Double_t Charge = 1.0; // Don't worry about charge for now
26 Double_t a = -Charge*G->B()*0.2998; // Normalized speed of light
27 Double_t C = a / (2 * pt); // pt in GeV, B in Tesla, C in meters
28 Double_t r2 = xx*xx + yy*yy;
29 Double_t cross = xx*py - yy*px;
30 Double_t T = TMath::Sqrt(pt*pt - 2 * a*cross + a*a*r2);
31 Double_t phi0 = TMath::ATan2((py - a*xx) / T, (px + a*yy) / T);
32 Double_t D;
33 if (pt < 10.0) D = (T - pt) / a;
34 else D = (-2 * cross + a*r2) / (T + pt);
35 Double_t B = C*TMath::Sqrt((r2 - D*D) / (1 + 2 * C*D));
36 Double_t st = TMath::ASin(B) / C;
37 Double_t ct = pz / pt;
38 Double_t z0 = zz - ct*st;
39 fpar[0] = D;
40 fpar[1] = phi0;
41 fpar[2] = C;
42 fpar[3] = z0;
43 fpar[4] = ct;
44 // Init covariances
45 fCov.ResizeTo(5, 5);
46}
47
48SolTrack::SolTrack(Double_t D, Double_t phi0, Double_t C, Double_t z0, Double_t ct, SolGeom *G)
49{
50 fG = G;
51 // Store parameters
52 fpar[0] = D;
53 fpar[1] = phi0;
54 fpar[2] = C;
55 fpar[3] = z0;
56 fpar[4] = ct;
57 // Store momentum
58 Double_t pt = G->B()*0.2998 / TMath::Abs(2 * C);
59 Double_t px = pt*TMath::Cos(phi0);
60 Double_t py = pt*TMath::Sin(phi0);
61 Double_t pz = pt*ct;
62
63 fp[0] = px; fp[1] = py; fp[2] = pz;
64 fx[0] = -D*TMath::Sin(phi0); fx[1] = D*TMath::Cos(phi0); fx[2] = z0;
65 // Init covariances
66 fCov.ResizeTo(5, 5);
67}
68// Destructor
69SolTrack::~SolTrack()
70{
71 fCov.Clear();
72}
73// Calculate intersection with given layer
74Bool_t SolTrack::HitLayer(Int_t il, Double_t &R, Double_t &phi, Double_t &zz)
75{
76 Double_t Di = D();
77 Double_t phi0i = phi0();
78 Double_t Ci = C();
79 Double_t z0i = z0();
80 Double_t cti = ct();
81
82 R = 0; phi = 0; zz = 0;
83
84 Bool_t val = kFALSE;
85 if (fG->lTyp(il) == 1) // Cylinder: layer at constant R
86 {
87 R = fG->lPos(il);
88 Double_t argph = (Ci*R + (1 + Ci*Di)*Di / R) / (1. + 2.*Ci*Di);
89 if (TMath::Abs(argph) < 1.0)
90 {
91 Double_t argz = Ci*TMath::Sqrt((R*R - Di*Di) / (1 + 2 * Ci*Di));
92 if (TMath::Abs(argz) < 1.0)
93 {
94 zz = z0i + cti*TMath::ASin(argz) / Ci;
95 if (zz > fG->lxMin(il) && zz < fG->lxMax(il))
96 {
97 phi = phi0i + TMath::ASin(argph);
98 val = kTRUE;
99 }
100 }
101 }
102 }
103 else if (fG->lTyp(il) == 2) // disk: layer at constant z
104 {
105 zz = fG->lPos(il);
106 Double_t arg = Ci*(zz - z0i) / cti;
107 if (TMath::Abs(arg) < 1.0 && (zz - z0i) / cti > 0)
108 {
109 R = TMath::Sqrt(Di*Di + (1. + 2.*Ci*Di)*pow(TMath::Sin(arg), 2) / (Ci*Ci));
110 if (R > fG->lxMin(il) && R < fG->lxMax(il))
111 {
112 Double_t arg1 = (Ci*R + (1 + Ci*Di)*Di / R) / (1. + 2.*Ci*Di);
113 if (TMath::Abs(arg1) < 1.0)
114 {
115 phi = phi0i + TMath::ASin(arg1);
116 val = kTRUE;
117 }
118 }
119 }
120 }
121 //
122 return val;
123}
124// # of layers hit
125Int_t SolTrack::nHit()
126{
127 Int_t kh = 0;
128 Double_t R; Double_t phi; Double_t zz;
129 for (Int_t i = 0; i < fG->Nl(); i++)
130 if (HitLayer(i, R, phi, zz))kh++;
131
132 return kh;
133}
134// List of layers hit with intersections
135Int_t SolTrack::HitList(Int_t *&ihh, Double_t *&rhh, Double_t *&zhh)
136{
137 // Return lists of hits associated to a track including all scattering layers.
138 // Return value is the total number of measurement hits
139 // kmh = total number of measurement layers hit for given type
140 // ihh = pointer to layer number
141 // rhh = radius of hit
142 // zhh = z of hit
143
144 // ***** NB: double layers with stereo on lower layer not included
145
146 Int_t kh = 0; // Number of layers hit
147 Int_t kmh = 0; // Number of measurement layers of given type
148 for (Int_t i = 0; i < fG->Nl(); i++)
149 {
150 Double_t R; Double_t phi; Double_t zz;
151 if (HitLayer(i, R, phi, zz)) // Only barrel type layers
152 {
153 zhh[kh] = zz;
154 rhh[kh] = R;
155 ihh[kh] = i;
156 if (fG->isMeasure(i))kmh++;
157 kh++;
158 }
159 }
160
161 return kmh;
162}
163// Covariance matrix estimation
164void SolTrack::CovCalc(Bool_t Res, Bool_t MS)
165{
166 // Input flags:
167 // Res = .TRUE. turn on resolution effects/Use standard resolutions
168 // .FALSE. set all resolutions to 0
169 // MS = .TRUE. include Multiple Scattering
170 // Assumptions:
171 // 1. Measurement layers can do one or two measurements
172 // 2. On disks at constant z:
173 // - Upper side measurement is phi
174 // - Lower side measurement is R
175
176 // Fill list of layers hit
177 Int_t ntry = 0;
178 Int_t ntrymax = 0;
179 Int_t Nhit = nHit(); // Total number of layers hit
180 Double_t *zhh = new Double_t[Nhit]; // z of hit
181 Double_t *rhh = new Double_t[Nhit]; // r of hit
182 Double_t *dhh = new Double_t[Nhit]; // distance of hit from origin
183 Int_t *ihh = new Int_t[Nhit]; // true index of layer
184 Int_t kmh; // Number of measurement layers hit
185
186 kmh = HitList(ihh, rhh, zhh); // hit layer list
187 Int_t mTot = 0; // Total number of measurements
188 for (Int_t i = 0; i < Nhit; i++)
189 {
190 dhh[i] = TMath::Sqrt(rhh[i] * rhh[i] + zhh[i] * zhh[i]);
191 if (fG->isMeasure(ihh[i])) mTot += fG->lND(ihh[i]); // Count number of measurements
192 }
193 // Order hit list by increasing distance from origin
194 Int_t *hord = new Int_t[Nhit]; // hit order by increasing distance from origin
195 TMath::Sort(Nhit, dhh, hord, kFALSE); // Order by increasing distance from origin
196 Double_t *zh = new Double_t[Nhit]; // d-ordered z of hit
197 Double_t *rh = new Double_t[Nhit]; // d-ordered r of hit
198 Int_t *ih = new Int_t[Nhit]; // d-ordered true index of layer
199 for (Int_t i = 0; i < Nhit; i++)
200 {
201 Int_t il = hord[i]; // Hit layer numbering
202 zh[i] = zhh[il];
203 rh[i] = rhh[il];
204 ih[i] = ihh[il];
205 }
206 // Store interdistances and multiple scattering angles
207 Double_t sn2t = 1.0 / (1 + ct()*ct()); //sin^2 theta of track
208 Double_t cs2t = 1.0 - sn2t; //cos^2 theta
209 Double_t snt = TMath::Sqrt(sn2t); // sin theta
210 Double_t cst = TMath::Sqrt(cs2t); // cos theta
211 Double_t px0 = pt() * TMath::Cos(phi0()); // Momentum at minimum approach
212 Double_t py0 = pt() * TMath::Sin(phi0());
213 Double_t pz0 = pt() * ct();
214 TMatrixDSym dik(Nhit); dik.Zero(); // Distances between layers
215 Double_t *thms = new Double_t[Nhit]; // Scattering angles/plane
216 Double_t *cs = new Double_t[Nhit]; // Cosine of angle with layer normal
217 for (Int_t ii = 0; ii < Nhit; ii++) // Hit layer loop
218 {
219 Int_t i = ih[ii]; // Get true layer number
220 Double_t B = C()*TMath::Sqrt((rh[ii] * rh[ii] - D()*D()) / (1 + 2 * C()*D()));
221 Double_t pxi = px0*(1-2*B*B)-2*py0*B*TMath::Sqrt(1-B*B); // Momentum at scattering layer
222 Double_t pyi = py0*(1-2*B*B)+2*px0*B*TMath::Sqrt(1-B*B);
223 Double_t pzi = pz0;
224 Double_t ArgRp = (rh[ii]*C() + (1 + C() * D())*D() / rh[ii]) / (1 + 2 * C()*D());
225 Double_t phi = phi0() + TMath::ASin(ArgRp);
226 Double_t nx = TMath::Cos(phi); // Barrel layer normal
227 Double_t ny = TMath::Sin(phi);
228 Double_t nz = 0.0;
229 if (fG->lTyp(i) == 2) // this is Z layer
230 {
231 nx = 0.0;
232 ny = 0.0;
233 nz = 1.0;
234 }
235 Double_t corr = (pxi*nx + pyi * ny + pzi * nz) / p();
236 cs[ii] = corr;
237 Double_t Rlf = fG->lTh(i) / (corr*fG->lX0(i)); // Rad. length fraction
238 thms[ii] = 0.0136*TMath::Sqrt(Rlf)*(1.0 + 0.038*TMath::Log(Rlf)) / p(); // MS angle
239 if (!MS)thms[ii] = 0;
240 //
241 for (Int_t kk = 0; kk < ii; kk++) // Fill distances between layers
242 {
243 Double_t Ci = C();
244 dik(ii, kk) = (TMath::ASin(Ci*rh[ii])-TMath::ASin(Ci*rh[kk]))/(Ci*snt);
245 dik(kk, ii) = dik(ii, kk);
246 }
247 // Store momentum components for resolution correction cosines
248 Double_t *pRi = new Double_t[Nhit];
249 pRi[ii] = TMath::Abs(pxi * TMath::Cos(phi) + pyi * TMath::Sin(phi)); // Radial component
250 Double_t *pPhi = new Double_t[Nhit];
251 pPhi[ii] = TMath::Abs(pxi * TMath::Sin(phi) - pyi * TMath::Cos(phi)); // Phi component
252 }
253 // Fill measurement covariance
254 Int_t *mTl = new Int_t[mTot]; // Pointer from measurement number to true layer number
255 TMatrixDSym Sm(mTot); Sm.Zero(); // Measurement covariance
256 TMatrixD Rm(mTot, 5); // Derivative matrix
257 Int_t im = 0;
258 // Fill derivatives and error matrix with MS
259 Double_t AngMax = 90.; Double_t AngMx = AngMax * TMath::Pi() / 180.;
260 Double_t csMin = TMath::Cos(AngMx); // Set maximum angle wrt normal
261 //
262 for (Int_t ii = 0; ii < Nhit; ii++)
263 {
264 Int_t i = ih[ii]; // True layer number
265 Int_t ityp = fG->lTyp(i); // Layer type Barrel or Z
266 Int_t nmeai = fG->lND(i); // # measurements in layer
267 if (fG->isMeasure(i) && nmeai >0 && cs[ii] > csMin)
268 {
269 Double_t Di = D(); // Get true track parameters
270 Double_t phi0i = phi0();
271 Double_t Ci = C();
272 Double_t z0i = z0();
273 Double_t cti = ct();
274 //
275 Double_t Ri = rh[ii];
276 Double_t ArgRp = (Ri*Ci + (1 + Ci * Di)*Di / Ri) / (1 + 2 * Ci*Di);
277 Double_t ArgRz = Ci * TMath::Sqrt((Ri*Ri - Di * Di) / (1 + 2 * Ci*Di));
278 TVectorD dRphi(5); dRphi.Zero(); // R-phi derivatives @ const. R
279 TVectorD dRz(5); dRz.Zero(); // z derivatives @ const. R
280 // Derivative overflow protection
281 Double_t dMin = 0.8;
282 dRphi(0) = (1 - 2 * Ci*Ci*Ri*Ri) /
283 TMath::Max(dMin,TMath::Sqrt(1 - ArgRp * ArgRp)); // D derivative
284 dRphi(1) = Ri; // phi0 derivative
285 dRphi(2) = Ri * Ri /
286 TMath::Max(dMin,TMath::Sqrt(1 - ArgRp * ArgRp)); // C derivative
287 dRphi(3) = 0.0; // z0 derivative
288 dRphi(4) = 0.0; // cot(theta) derivative
289
290 dRz(0) = -cti * Di /
291 (Ri*TMath::Max(dMin,TMath::Sqrt(1 - Ci * Ci*Ri*Ri))); // D
292 dRz(1) = 0.0; // Phi0
293 dRz(2) = cti * (Ri*Ci / TMath::Sqrt(1-Ri*Ri*Ci*Ci) -
294 TMath::ASin(Ri*Ci)) / (Ci*Ci); // C
295 dRz(3) = 1.0; // Z0
296 dRz(4) = TMath::ASin(ArgRz) / Ci; // Cot(theta)
297
298 for (Int_t nmi = 0; nmi < nmeai; nmi++)
299 {
300 mTl[im] = i;
301 Double_t stri = 0;
302 Double_t sig = 0;
303 if (nmi + 1 == 1) // Upper layer measurements
304 {
305 stri = fG->lStU(i); // Stereo angle
306 Double_t csa = TMath::Cos(stri);
307 Double_t ssa = TMath::Sin(stri);
308 sig = fG->lSgU(i); // Resolution
309 if (ityp == 1) // Barrel type layer (Measure R-phi, stereo or z at const. R)
310 {
311 // Almost exact solution (CD<<1, D<<R)
312 Rm(im, 0) = csa * dRphi(0) - ssa * dRz(0); // D derivative
313 Rm(im, 1) = csa * dRphi(1) - ssa * dRz(1); // phi0 derivative
314 Rm(im, 2) = csa * dRphi(2) - ssa * dRz(2); // C derivative
315 Rm(im, 3) = csa * dRphi(3) - ssa * dRz(3); // z0 derivative
316 Rm(im, 4) = csa * dRphi(4) - ssa * dRz(4); // cot(theta) derivative
317 }
318 if (ityp == 2) // Z type layer (Measure phi at const. Z)
319 {
320 Rm(im, 0) = 1.0; // D derivative
321 Rm(im, 1) = rh[ii]; // phi0 derivative
322 Rm(im, 2) = rh[ii] * rh[ii]; // C derivative
323 Rm(im, 3) = 0; // z0 derivative
324 Rm(im, 4) = 0; // cot(theta) derivative
325 }
326 }
327 if (nmi + 1 == 2) // Lower layer measurements
328 {
329 stri = fG->lStL(i); // Stereo angle
330 Double_t csa = TMath::Cos(stri);
331 Double_t ssa = TMath::Sin(stri);
332 sig = fG->lSgL(i); // Resolution
333 if (ityp == 1) // Barrel type layer (measure R-phi, stereo or z at const. R)
334 {
335 // Almost exact solution (CD<<1, D<<R)
336 Rm(im, 0) = csa * dRphi(0) - ssa * dRz(0); // D derivative
337 Rm(im, 1) = csa * dRphi(1) - ssa * dRz(1); // phi0 derivative
338 Rm(im, 2) = csa * dRphi(2) - ssa * dRz(2); // C derivative
339 Rm(im, 3) = csa * dRphi(3) - ssa * dRz(3); // z0 derivative
340 Rm(im, 4) = csa * dRphi(4) - ssa * dRz(4); // cot(theta) derivative
341 }
342 if (ityp == 2) // Z type layer (Measure R at const. z)
343 {
344 Rm(im, 0) = 0; // D derivative
345 Rm(im, 1) = 0; // phi0 derivative
346 Rm(im, 2) = 0; // C derivative
347 Rm(im, 3) = -1.0 / ct(); // z0 derivative
348 Rm(im, 4) = -rh[ii] / ct(); // cot(theta) derivative
349 }
350 }
351 // Derivative calculation completed
352 // Now calculate measurement error matrix
353 Int_t km = 0;
354 for (Int_t kk = 0; kk <= ii; kk++)
355 {
356 Int_t k = ih[kk]; // True layer number
357 Int_t ktyp = fG->lTyp(k); // Layer type Barrel or
358 Int_t nmeak = fG->lND(k); // # measurements in layer
359 if (fG->isMeasure(k) && nmeak > 0 &&cs[kk] > csMin)
360 {
361 for (Int_t nmk = 0; nmk < nmeak; nmk++)
362 {
363 Double_t strk = 0;
364 if (nmk + 1 == 1) strk = fG->lStU(k); // Stereo angle
365 if (nmk + 1 == 2) strk = fG->lStL(k); // Stereo angle
366 if (im == km && Res) Sm(im, km) += sig*sig; // Detector resolution on diagonal
367 //
368 // Loop on all layers below for MS contributions
369 for (Int_t jj = 0; jj < kk; jj++)
370 {
371 Double_t di = dik(ii, jj);
372 Double_t dk = dik(kk, jj);
373 Double_t ms = thms[jj];
374 Double_t msk = ms; Double_t msi = ms;
375 if (ityp == 1) msi = ms / snt; // Barrel
376 else if (ityp == 2) msi = ms / cst; // Disk
377 if (ktyp == 1) msk = ms / snt; // Barrel
378 else if (ktyp == 2) msk = ms / cst; // Disk
379 Double_t ci = TMath::Cos(stri); Double_t si = TMath::Sin(stri);
380 Double_t ck = TMath::Cos(strk); Double_t sk = TMath::Sin(strk);
381 Sm(im, km) += di*dk*(ci*ck*ms*ms + si*sk*msi*msk); // Ms contribution
382 }
383 Sm(km, im) = Sm(im, km);
384 km++;
385 }
386 }
387 }
388 im++; mTot = im;
389 }
390 }
391 }
392 Sm.ResizeTo(mTot, mTot);
393 Rm.ResizeTo(mTot, 5);
394
395 // Calculate covariance from derivatives and measurement error matrix
396 TMatrixDSym DSmInv(mTot); DSmInv.Zero();
397 for (Int_t id = 0; id < mTot; id++) DSmInv(id, id) = 1.0 / TMath::Sqrt(Sm(id, id));
398 TMatrixDSym SmN = Sm.Similarity(DSmInv); // Normalize diagonal to 1
399 // Protected matrix inversions
400 TDecompChol Chl(SmN);
401 TMatrixDSym SmNinv = SmN;
402 if (Chl.Decompose())
403 {
404 Bool_t OK;
405 SmNinv = Chl.Invert(OK);
406 }
407 else
408 {
409 cout << "SolTrack::CovCalc: Error matrix not positive definite. Recovering ...." << endl;
410 if (ntry < ntrymax)
411 {
412 SmNinv.Print();
413 ntry++;
414 }
415 TMatrixDSym rSmN = MakePosDef(SmN); SmN = rSmN;
416 TDecompChol rChl(SmN);
417 SmNinv = SmN;
418 Bool_t OK = rChl.Decompose();
419 SmNinv = rChl.Invert(OK);
420 }
421 Sm = SmNinv.Similarity(DSmInv); // Error matrix inverted
422 TMatrixDSym H = Sm.SimilarityT(Rm); // Calculate half Hessian
423 // Normalize before inversion
424 const Int_t Npar = 5;
425 TMatrixDSym DHinv(Npar); DHinv.Zero();
426 for (Int_t i = 0; i < Npar; i++)DHinv(i, i) = 1.0 / TMath::Sqrt(H(i, i));
427 TMatrixDSym Hnrm = H.Similarity(DHinv);
428 // Invert and restore
429 Hnrm.Invert();
430 fCov = Hnrm.Similarity(DHinv);
431}
432
433// Force positive definitness in normalized matrix
434TMatrixDSym SolTrack::MakePosDef(TMatrixDSym NormMat)
435{
436 // Input: symmetric matrix with 1's on diagonal
437 // Output: positive definite matrix with 1's on diagonal
438
439 // Default return value
440 TMatrixDSym rMatN = NormMat;
441 // Check the diagonal
442 Bool_t Check = kFALSE;
443 Int_t Size = NormMat.GetNcols();
444 for (Int_t i = 0; i < Size; i++)if (TMath::Abs(NormMat(i, i) - 1.0)>1.0E-15)Check = kTRUE;
445 if (Check)
446 {
447 cout << "SolTrack::MakePosDef: input matrix doesn't have 1 on diagonal. Abort." << endl;
448 return rMatN;
449 }
450 // Diagonalize matrix
451 TMatrixDSymEigen Eign(NormMat);
452 TMatrixD U = Eign.GetEigenVectors();
453 TVectorD lambda = Eign.GetEigenValues();
454 // Reset negative eigenvalues to small positive value
455 TMatrixDSym D(Size); D.Zero(); Double_t eps = 1.0e-13;
456 for (Int_t i = 0; i < Size; i++)
457 {
458 D(i, i) = lambda(i);
459 if (lambda(i) <= 0) D(i, i) = eps;
460 }
461 // Rebuild matrix
462 TMatrixD Ut(TMatrixD::kTransposed, U);
463 TMatrixD rMat = (U*D)*Ut; // Now it is positive defite
464 // Restore all ones on diagonal
465 for (Int_t i1 = 0; i1 < Size; i1++)
466 {
467 Double_t rn1 = TMath::Sqrt(rMat(i1, i1));
468 for (Int_t i2 = 0; i2 <= i1; i2++)
469 {
470 Double_t rn2 = TMath::Sqrt(rMat(i2, i2));
471 rMatN(i1, i2) = 0.5*(rMat(i1, i2) + rMat(i2, i1)) / (rn1*rn2);
472 rMatN(i2, i1) = rMatN(i1, i2);
473 }
474 }
475 return rMatN;
476}
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