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87eecb52 | 1 | /************************************************************************** |
2 | * Copyright(c) 1998-2003, 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 | // // | |
17 | // A straight line is coded as a point (3 Double_t) and // | |
18 | // 3 direction cosines // | |
19 | // // | |
20 | /////////////////////////////////////////////////////////////////// | |
21 | #include <Riostream.h> | |
87eecb52 | 22 | #include <TTree.h> |
87eecb52 | 23 | #include "AliITSStrLine.h" |
24 | ||
25 | ClassImp(AliITSStrLine) | |
26 | ||
27 | //________________________________________________________ | |
28 | AliITSStrLine::AliITSStrLine() { | |
29 | // Default constructor | |
30 | for(Int_t i=0;i<3;i++) { | |
31 | fP0[i] = 0.; | |
32 | fCd[i] = 0.; | |
33 | } | |
34 | fTpar = 0.; | |
35 | SetDebug(); | |
36 | } | |
37 | ||
38 | //________________________________________________________ | |
39 | AliITSStrLine::AliITSStrLine(Double_t *point, Double_t *cd) { | |
40 | // Standard constructor | |
41 | Double_t norm = 0.; | |
42 | for(Int_t i=0;i<3;i++)norm+=cd[i]*cd[i]; | |
43 | if(norm) { | |
44 | norm = TMath::Sqrt(norm); | |
45 | for(Int_t i=0;i<3;i++) cd[i]/=norm; | |
46 | } | |
47 | else { | |
48 | Error("AliITSStrLine","Null direction cosines!!!"); | |
49 | } | |
50 | SetP0(point); | |
51 | SetCd(cd); | |
52 | fTpar = 0.; | |
53 | SetDebug(); | |
54 | } | |
55 | ||
56 | //________________________________________________________ | |
57 | AliITSStrLine::~AliITSStrLine() { | |
58 | // destructor | |
59 | } | |
60 | ||
61 | //________________________________________________________ | |
62 | void AliITSStrLine::PrintStatus() const { | |
63 | // Print current status | |
64 | cout <<"=======================================================\n"; | |
65 | cout <<"Direction cosines: "; | |
66 | for(Int_t i=0;i<3;i++)cout <<fCd[i]<<"; "; | |
67 | cout <<endl; | |
68 | cout <<"Known point: "; | |
69 | for(Int_t i=0;i<3;i++)cout <<fP0[i]<<"; "; | |
70 | cout <<endl; | |
71 | cout <<"Current value for the parameter: "<<fTpar<<endl; | |
72 | cout <<" Debug flag: "<<fDebug<<endl; | |
73 | } | |
74 | ||
66e811e2 | 75 | //________________________________________________________ |
76 | Int_t AliITSStrLine::IsParallelTo(AliITSStrLine *line) const { | |
77 | // returns 1 if lines are parallel, 0 if not paralel | |
78 | Double_t cd2[3]; | |
79 | line->GetCd(cd2); | |
80 | Double_t vecpx=fCd[1]*cd2[2]-fCd[2]*cd2[1]; | |
81 | if(vecpx!=0) return 0; | |
82 | Double_t vecpy=-fCd[0]*cd2[2]+fCd[2]*cd2[0]; | |
83 | if(vecpy!=0) return 0; | |
84 | Double_t vecpz=fCd[0]*cd2[1]-fCd[1]*cd2[0]; | |
85 | if(vecpz!=0) return 0; | |
86 | return 1; | |
87 | } | |
87eecb52 | 88 | //________________________________________________________ |
89 | Int_t AliITSStrLine::Crossrphi(AliITSStrLine *line){ | |
90 | // Cross 2 lines in the X-Y plane | |
91 | Double_t p2[3]; | |
92 | Double_t cd2[3]; | |
93 | line->GetP0(p2); | |
94 | line->GetCd(cd2); | |
95 | Double_t a=fCd[0]; | |
96 | Double_t b=-cd2[0]; | |
97 | Double_t c=p2[0]-fP0[0]; | |
98 | Double_t d=fCd[1]; | |
99 | Double_t e=-cd2[1]; | |
100 | Double_t f=p2[1]-fP0[1]; | |
101 | Double_t deno = a*e-b*d; | |
102 | Int_t retcode = 0; | |
103 | if(deno != 0.) { | |
104 | fTpar = (c*e-b*f)/deno; | |
105 | } | |
106 | else { | |
107 | retcode = -1; | |
108 | } | |
109 | return retcode; | |
110 | } | |
111 | ||
112 | //________________________________________________________ | |
66e811e2 | 113 | Int_t AliITSStrLine::CrossPoints(AliITSStrLine *line, Double_t *point1, Double_t *point2){ |
87eecb52 | 114 | // Looks for the crossing point estimated starting from the |
115 | // DCA segment | |
116 | Double_t p2[3]; | |
117 | Double_t cd2[3]; | |
118 | line->GetP0(p2); | |
119 | line->GetCd(cd2); | |
120 | Int_t i; | |
121 | Double_t k1 = 0; | |
122 | for(i=0;i<3;i++)k1+=(fP0[i]-p2[i])*fCd[i]; | |
123 | Double_t k2 = 0; | |
124 | for(i=0;i<3;i++)k2+=(fP0[i]-p2[i])*cd2[i]; | |
125 | Double_t a11 = 0; | |
126 | for(i=0;i<3;i++)a11+=fCd[i]*cd2[i]; | |
127 | Double_t a22 = -a11; | |
128 | Double_t a21 = 0; | |
129 | for(i=0;i<3;i++)a21+=cd2[i]*cd2[i]; | |
130 | Double_t a12 = 0; | |
131 | for(i=0;i<3;i++)a12-=fCd[i]*fCd[i]; | |
132 | Double_t deno = a11*a22-a21*a12; | |
133 | if(deno == 0.) return -1; | |
134 | fTpar = (a11*k2-a21*k1) / deno; | |
135 | Double_t par2 = (k1*a22-k2*a12) / deno; | |
136 | line->SetPar(par2); | |
87eecb52 | 137 | GetCurrentPoint(point1); |
138 | line->GetCurrentPoint(point2); | |
87eecb52 | 139 | return 0; |
140 | } | |
66e811e2 | 141 | //________________________________________________________________ |
142 | Int_t AliITSStrLine::Cross(AliITSStrLine *line, Double_t *point){ | |
143 | ||
144 | //Finds intersection between lines | |
145 | Double_t point1[3]; | |
146 | Double_t point2[3]; | |
147 | Int_t retcod=CrossPoints(line,point1,point2); | |
148 | if(retcod==0){ | |
149 | for(Int_t i=0;i<3;i++)point[i]=(point1[i]+point2[i])/2.; | |
150 | return 0; | |
151 | }else{ | |
152 | return -1; | |
153 | } | |
154 | } | |
155 | ||
156 | //___________________________________________________________ | |
157 | Double_t AliITSStrLine::GetDCA(AliITSStrLine *line){ | |
158 | //Returns the distance of closest approach between two lines | |
159 | Double_t p2[3]; | |
160 | Double_t cd2[3]; | |
161 | line->GetP0(p2); | |
162 | line->GetCd(cd2); | |
163 | Int_t i; | |
164 | Int_t ispar=IsParallelTo(line); | |
165 | if(ispar){ | |
166 | Double_t dist1q=0,dist2=0,mod=0; | |
167 | for(i=0;i<3;i++){ | |
168 | dist1q+=(fP0[i]-p2[i])*(fP0[i]-p2[i]); | |
169 | dist2+=(fP0[i]-p2[i])*fCd[i]; | |
170 | mod+=fCd[i]*fCd[i]; | |
171 | } | |
172 | if(mod!=0){ | |
173 | dist2/=mod; | |
174 | return TMath::Sqrt(dist1q-dist2*dist2); | |
175 | }else{return -1;} | |
176 | }else{ | |
177 | Double_t perp[3]; | |
178 | perp[0]=fCd[1]*cd2[2]-fCd[2]*cd2[1]; | |
179 | perp[1]=-fCd[0]*cd2[2]+fCd[2]*cd2[0]; | |
180 | perp[2]=fCd[0]*cd2[1]-fCd[1]*cd2[0]; | |
181 | Double_t mod=0,dist=0; | |
182 | for(i=0;i<3;i++){ | |
183 | mod+=perp[i]*perp[i]; | |
184 | dist+=(fP0[i]-p2[i])*perp[i]; | |
185 | } | |
186 | mod=sqrt(mod); | |
187 | if(mod!=0){ | |
188 | dist/=mod; | |
189 | return TMath::Abs(dist); | |
190 | }else{return -1;} | |
191 | } | |
192 | } | |
87eecb52 | 193 | //________________________________________________________ |
66e811e2 | 194 | void AliITSStrLine::GetCurrentPoint(Double_t *point) const { |
87eecb52 | 195 | // Fills the array point with the current value on the line |
196 | for(Int_t i=0;i<3;i++)point[i]=fP0[i]+fCd[i]*fTpar; | |
197 | } |