[u/mrichter/AliRoot.git] / STEER / ESD / AliStrLine.cxx

/**************************************************************************
 * Copyright(c) 1998-2003, ALICE Experiment at CERN, All rights reserved. *
 *                                                                        *
 * Author: The ALICE Off-line Project.                                    *
 * Contributors are mentioned in the code where appropriate.              *
 *                                                                        *
 * Permission to use, copy, modify and distribute this software and its   *
 * documentation strictly for non-commercial purposes is hereby granted   *
 * without fee, provided that the above copyright notice appears in all   *
 * copies and that both the copyright notice and this permission notice   *
 * appear in the supporting documentation. The authors make no claims     *
 * about the suitability of this software for any purpose. It is          *
 * provided "as is" without express or implied warranty.                  *
 **************************************************************************/

/* $Id$ */

///////////////////////////////////////////////////////////////////
//                                                               //
// A straight line is coded as a point (3 Double_t) and           //
// 3 direction cosines                                           //
//                                                               //
///////////////////////////////////////////////////////////////////

#include <Riostream.h>
#include <TMath.h>

#include "AliStrLine.h"

ClassImp(AliStrLine)

//________________________________________________________
AliStrLine::AliStrLine() :
  TObject(),
  fWMatrix(0),
  fTpar(0)
 {
  // Default constructor
  for(Int_t i=0;i<3;i++) {
    fP0[i] = 0.;
    fSigma2P0[i] = 0.;
    fCd[i] = 0.;
  }
  SetIdPoints(65535,65535);
}

//________________________________________________________
AliStrLine::AliStrLine(const Double_t *const point, const Double_t *const cd, Bool_t twopoints, UShort_t id1, UShort_t id2) :
  TObject(),
  fWMatrix(0),
  fTpar(0)
{
  // Standard constructor
  // if twopoints is true:  point and cd are the 3D coordinates of
  //                        two points defininig the straight line
  // if twopoint is false: point represents the 3D coordinates of a point
  //                       belonging to the straight line and cd is the
  //                       direction in space
  for(Int_t i=0;i<3;i++)
    fSigma2P0[i] = 0.;

  if(twopoints)
    InitTwoPoints(point,cd);
  else 
    InitDirection(point,cd);

  SetIdPoints(id1,id2);
}


//________________________________________________________
AliStrLine::AliStrLine(const Double_t *const point, const Double_t *const sig2point, const Double_t *const cd, Bool_t twopoints, UShort_t id1, UShort_t id2) :
  TObject(),
  fWMatrix(0),
  fTpar(0)
{
  // Standard constructor
  // if twopoints is true:  point and cd are the 3D coordinates of
  //                        two points defininig the straight line
  // if twopoint is false: point represents the 3D coordinates of a point
  //                       belonging to the straight line and cd is the
  //                       direction in space
  for(Int_t i=0;i<3;i++)
    fSigma2P0[i] = sig2point[i];

  if(twopoints)
    InitTwoPoints(point,cd);
  else 
    InitDirection(point,cd);

  SetIdPoints(id1,id2);
}

//________________________________________________________
AliStrLine::AliStrLine(const Double_t *const point, const Double_t *const sig2point, const Double_t *const wmat, const Double_t *const cd, Bool_t twopoints, UShort_t id1, UShort_t id2) :
  TObject(),
  fWMatrix(0),
  fTpar(0)
{
  // Standard constructor
  // if twopoints is true:  point and cd are the 3D coordinates of
  //                        two points defininig the straight line
  // if twopoint is false: point represents the 3D coordinates of a point
  //                       belonging to the straight line and cd is the
  //                       direction in space
  Int_t k = 0;
  fWMatrix = new Double_t [6];
  for(Int_t i=0;i<3;i++){ 
    fSigma2P0[i] = sig2point[i];
    for(Int_t j=0;j<3;j++)if(j>=i)fWMatrix[k++]=wmat[3*i+j];
  }
  if(twopoints)
    InitTwoPoints(point,cd);
  else 
    InitDirection(point,cd);

  SetIdPoints(id1,id2);
}

//________________________________________________________
AliStrLine::AliStrLine(const AliStrLine &source):TObject(source),
fWMatrix(0),
fTpar(source.fTpar){
  // copy constructor
  for(Int_t i=0;i<3;i++){
    fP0[i]=source.fP0[i];
    fSigma2P0[i]=source.fSigma2P0[i];
    fCd[i]=source.fCd[i];
  }
  if(source.fWMatrix){
    fWMatrix = new Double_t [6];
    for(Int_t i=0;i<6;i++)fWMatrix[i]=source.fWMatrix[i];
  }
  for(Int_t i=0;i<2;i++) fIdPoint[i]=source.fIdPoint[i];
}

//________________________________________________________
AliStrLine& AliStrLine::operator=(const AliStrLine& source){
  // Assignment operator
  if(this !=&source){
    this->~AliStrLine();
    new(this)AliStrLine(source);
  }
  return *this;
}

//________________________________________________________
void AliStrLine::GetWMatrix(Double_t *wmat)const {
// Getter for weighting matrix, as a [9] dim. array
  if(!fWMatrix)return;
  Int_t k = 0;
  for(Int_t i=0;i<3;i++){
    for(Int_t j=0;j<3;j++){
      if(j>=i){
	wmat[3*i+j]=fWMatrix[k++];
      }
      else{
	wmat[3*i+j]=wmat[3*j+i];
      }
    }
  }
} 

//________________________________________________________
void AliStrLine::SetWMatrix(const Double_t *wmat) {
// Setter for weighting matrix, strating from a [9] dim. array
  if(fWMatrix)delete [] fWMatrix;
  fWMatrix = new Double_t [6];
  Int_t k = 0;
  for(Int_t i=0;i<3;i++){
    for(Int_t j=0;j<3;j++)if(j>=i)fWMatrix[k++]=wmat[3*i+j];
  }
}

//________________________________________________________
void AliStrLine::InitDirection(const Double_t *const point, const Double_t *const cd)
{
  // Initialization from a point and a direction
  Double_t norm = cd[0]*cd[0]+cd[1]*cd[1]+cd[2]*cd[2];

  if(norm) {
    norm = TMath::Sqrt(1./norm);
    for(Int_t i=0;i<3;++i) {
      fP0[i]=point[i];
      fCd[i]=cd[i]*norm;
    }
    fTpar = 0.;
  }
  else AliFatal("Null direction cosines!!!");
}

//________________________________________________________
void AliStrLine::InitTwoPoints(const Double_t *const pA, const Double_t *const pB)
{
  // Initialization from the coordinates of two
  // points in the space
  Double_t cd[3];
  for(Int_t i=0;i<3;i++)cd[i] = pB[i]-pA[i];
  InitDirection(pA,cd);
}

//________________________________________________________
AliStrLine::~AliStrLine() {
  // destructor
  if(fWMatrix)delete [] fWMatrix;
}

//________________________________________________________
void AliStrLine::PrintStatus() const {
  // Print current status
  cout <<"=======================================================\n";
  cout <<"Direction cosines: ";
  for(Int_t i=0;i<3;i++)cout <<fCd[i]<<"; ";
  cout <<endl;
  cout <<"Known point: ";
  for(Int_t i=0;i<3;i++)cout <<fP0[i]<<"; ";
  cout <<endl;
  cout <<"Error on known point: ";
  for(Int_t i=0;i<3;i++)cout <<TMath::Sqrt(fSigma2P0[i])<<"; ";
  cout <<endl;
  cout <<"Current value for the parameter: "<<fTpar<<endl;
}

//________________________________________________________
Int_t AliStrLine::IsParallelTo(const AliStrLine *line) const {
  // returns 1 if lines are parallel, 0 if not paralel
  const Double_t prec=1e-14;
  Double_t cd2[3];
  line->GetCd(cd2);

  Double_t vecpx=fCd[1]*cd2[2]-fCd[2]*cd2[1];
  Double_t mod=TMath::Abs(fCd[1]*cd2[2])+TMath::Abs(fCd[2]*cd2[1]);
  if(TMath::Abs(vecpx) > prec*mod) return 0;

  Double_t vecpy=-fCd[0]*cd2[2]+fCd[2]*cd2[0];
  mod=TMath::Abs(fCd[0]*cd2[2])+TMath::Abs(fCd[2]*cd2[0]);
  if(TMath::Abs(vecpy) > prec*mod) return 0;

  Double_t vecpz=fCd[0]*cd2[1]-fCd[1]*cd2[0];
  mod=TMath::Abs(fCd[0]*cd2[1])+TMath::Abs(fCd[1]*cd2[0]);
  if(TMath::Abs(vecpz) > prec) return 0;

  return 1;
}
//________________________________________________________
Int_t AliStrLine::Crossrphi(const AliStrLine *line)
{
  // Cross 2 lines in the X-Y plane
  const Double_t prec=1e-14;
  const Double_t big=1e20;
  Double_t p2[3];
  Double_t cd2[3];
  line->GetP0(p2);
  line->GetCd(cd2);
  Double_t a=fCd[0];
  Double_t b=-cd2[0];
  Double_t c=p2[0]-fP0[0];
  Double_t d=fCd[1];
  Double_t e=-cd2[1];
  Double_t f=p2[1]-fP0[1];
  Double_t deno = a*e-b*d;
  Double_t mod=TMath::Abs(a*e)+TMath::Abs(b*d);
  Int_t retcode = 0;
  if(TMath::Abs(deno) > prec*mod) {
    fTpar = (c*e-b*f)/deno;
  }
  else {
    fTpar = big;
    retcode = -1;
  }
  return retcode;
}

//________________________________________________________
Int_t AliStrLine::CrossPoints(AliStrLine *line, Double_t *point1, Double_t *point2){
  // Looks for the crossing point estimated starting from the
  // DCA segment
  const Double_t prec=1e-14;
  Double_t p2[3];
  Double_t cd2[3];
  line->GetP0(p2);
  line->GetCd(cd2);
  Int_t i;
  Double_t k1 = 0;
  Double_t k2 = 0;
  Double_t a11 = 0;
  for(i=0;i<3;i++){
    k1+=(fP0[i]-p2[i])*fCd[i];
    k2+=(fP0[i]-p2[i])*cd2[i];
    a11+=fCd[i]*cd2[i];
  }
  Double_t a22 = -a11;
  Double_t a21 = 0;
  Double_t a12 = 0;
  for(i=0;i<3;i++){
    a21+=cd2[i]*cd2[i];
    a12-=fCd[i]*fCd[i];
  }
  Double_t deno = a11*a22-a21*a12;
  Double_t mod = TMath::Abs(a11*a22)+TMath::Abs(a21*a12);
  if(TMath::Abs(deno) < prec*mod) return -1;
  fTpar = (a11*k2-a21*k1) / deno;
  Double_t par2 = (k1*a22-k2*a12) / deno;
  line->SetPar(par2);
  GetCurrentPoint(point1);
  line->GetCurrentPoint(point2);
  return 0;
}
//________________________________________________________________
Int_t AliStrLine::Cross(AliStrLine *line, Double_t *point)
{

  //Finds intersection between lines
  Double_t point1[3];
  Double_t point2[3];
  Int_t retcod=CrossPoints(line,point1,point2);
  if(retcod==0){
    for(Int_t i=0;i<3;i++)point[i]=(point1[i]+point2[i])/2.;
    return 0;
  }else{
    return -1;
  }
}

//___________________________________________________________
Double_t AliStrLine::GetDCA(const AliStrLine *line) const
{
  //Returns the distance of closest approach between two lines
  const Double_t prec=1e-14;
  Double_t p2[3];
  Double_t cd2[3];
  line->GetP0(p2);
  line->GetCd(cd2);
  Int_t i;
  Int_t ispar=IsParallelTo(line);
  if(ispar){
    Double_t dist1q=0,dist2=0,mod=0;
    for(i=0;i<3;i++){
      dist1q+=(fP0[i]-p2[i])*(fP0[i]-p2[i]);
      dist2+=(fP0[i]-p2[i])*fCd[i];
      mod+=fCd[i]*fCd[i];
    }
    if(TMath::Abs(mod) > prec){
      dist2/=mod;
      return TMath::Sqrt(dist1q-dist2*dist2);
    }else{return -1;}
  }else{
     Double_t perp[3];
     perp[0]=fCd[1]*cd2[2]-fCd[2]*cd2[1];
     perp[1]=-fCd[0]*cd2[2]+fCd[2]*cd2[0];
     perp[2]=fCd[0]*cd2[1]-fCd[1]*cd2[0];
     Double_t mod=0,dist=0;
     for(i=0;i<3;i++){
       mod+=perp[i]*perp[i];
       dist+=(fP0[i]-p2[i])*perp[i];
     }
     if(TMath::Abs(mod) > prec) {
       return TMath::Abs(dist/TMath::Sqrt(mod));
     } else return -1;
  }
}
//________________________________________________________
void AliStrLine::GetCurrentPoint(Double_t *point) const {
  // Fills the array point with the current value on the line
  for(Int_t i=0;i<3;i++)point[i]=fP0[i]+fCd[i]*fTpar;
}

//________________________________________________________
Double_t AliStrLine::GetDistFromPoint(const Double_t *point) const 
{
  // computes distance from point 
  AliStrLine tmpline(point, fCd, kFALSE);
  return GetDCA(&tmpline);
}
Commit	Line	Data
	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	/* $Id$ */
	17
	18	///////////////////////////////////////////////////////////////////
	19	// //
	20	// A straight line is coded as a point (3 Double_t) and //
	21	// 3 direction cosines //
	22	// //
	23	///////////////////////////////////////////////////////////////////
	24
	25	#include <Riostream.h>
	26	#include <TMath.h>
	27
	28	#include "AliStrLine.h"
	29
	30	ClassImp(AliStrLine)
	31
	32	//________________________________________________________
	33	AliStrLine::AliStrLine() :
	34	TObject(),
	35	fWMatrix(0),
	36	fTpar(0)
	37	{
	38	// Default constructor
	39	for(Int_t i=0;i<3;i++) {
	40	fP0[i] = 0.;
	41	fSigma2P0[i] = 0.;
	42	fCd[i] = 0.;
	43	}
	44	SetIdPoints(65535,65535);
	45	}
	46
	47	//________________________________________________________
	48	AliStrLine::AliStrLine(const Double_t const point, const Double_t const cd, Bool_t twopoints, UShort_t id1, UShort_t id2) :
	49	TObject(),
	50	fWMatrix(0),
	51	fTpar(0)
	52	{
	53	// Standard constructor
	54	// if twopoints is true: point and cd are the 3D coordinates of
	55	// two points defininig the straight line
	56	// if twopoint is false: point represents the 3D coordinates of a point
	57	// belonging to the straight line and cd is the
	58	// direction in space
	59	for(Int_t i=0;i<3;i++)
	60	fSigma2P0[i] = 0.;
	61
	62	if(twopoints)
	63	InitTwoPoints(point,cd);
	64	else
	65	InitDirection(point,cd);
	66
	67	SetIdPoints(id1,id2);
	68	}
	69
	70
	71	//________________________________________________________
	72	AliStrLine::AliStrLine(const Double_t const point, const Double_t const sig2point, const Double_t *const cd, Bool_t twopoints, UShort_t id1, UShort_t id2) :
	73	TObject(),
	74	fWMatrix(0),
	75	fTpar(0)
	76	{
	77	// Standard constructor
	78	// if twopoints is true: point and cd are the 3D coordinates of
	79	// two points defininig the straight line
	80	// if twopoint is false: point represents the 3D coordinates of a point
	81	// belonging to the straight line and cd is the
	82	// direction in space
	83	for(Int_t i=0;i<3;i++)
	84	fSigma2P0[i] = sig2point[i];
	85
	86	if(twopoints)
	87	InitTwoPoints(point,cd);
	88	else
	89	InitDirection(point,cd);
	90
	91	SetIdPoints(id1,id2);
	92	}
	93
	94	//________________________________________________________
	95	AliStrLine::AliStrLine(const Double_t const point, const Double_t const sig2point, const Double_t const wmat, const Double_t const cd, Bool_t twopoints, UShort_t id1, UShort_t id2) :
	96	TObject(),
	97	fWMatrix(0),
	98	fTpar(0)
	99	{
	100	// Standard constructor
	101	// if twopoints is true: point and cd are the 3D coordinates of
	102	// two points defininig the straight line
	103	// if twopoint is false: point represents the 3D coordinates of a point
	104	// belonging to the straight line and cd is the
	105	// direction in space
	106	Int_t k = 0;
	107	fWMatrix = new Double_t [6];
	108	for(Int_t i=0;i<3;i++){
	109	fSigma2P0[i] = sig2point[i];
	110	for(Int_t j=0;j<3;j++)if(j>=i)fWMatrix[k++]=wmat[3*i+j];
	111	}
	112	if(twopoints)
	113	InitTwoPoints(point,cd);
	114	else
	115	InitDirection(point,cd);
	116
	117	SetIdPoints(id1,id2);
	118	}
	119
	120	//________________________________________________________
	121	AliStrLine::AliStrLine(const AliStrLine &source):TObject(source),
	122	fWMatrix(0),
	123	fTpar(source.fTpar){
	124	// copy constructor
	125	for(Int_t i=0;i<3;i++){
	126	fP0[i]=source.fP0[i];
	127	fSigma2P0[i]=source.fSigma2P0[i];
	128	fCd[i]=source.fCd[i];
	129	}
	130	if(source.fWMatrix){
	131	fWMatrix = new Double_t [6];
	132	for(Int_t i=0;i<6;i++)fWMatrix[i]=source.fWMatrix[i];
	133	}
	134	for(Int_t i=0;i<2;i++) fIdPoint[i]=source.fIdPoint[i];
	135	}
	136
	137	//________________________________________________________
	138	AliStrLine& AliStrLine::operator=(const AliStrLine& source){
	139	// Assignment operator
	140	if(this !=&source){
	141	this->~AliStrLine();
	142	new(this)AliStrLine(source);
	143	}
	144	return *this;
	145	}
	146
	147	//________________________________________________________
	148	void AliStrLine::GetWMatrix(Double_t *wmat)const {
	149	// Getter for weighting matrix, as a [9] dim. array
	150	if(!fWMatrix)return;
	151	Int_t k = 0;
	152	for(Int_t i=0;i<3;i++){
	153	for(Int_t j=0;j<3;j++){
	154	if(j>=i){
	155	wmat[3*i+j]=fWMatrix[k++];
	156	}
	157	else{
	158	wmat[3i+j]=wmat[3j+i];
	159	}
	160	}
	161	}
	162	}
	163
	164	//________________________________________________________
	165	void AliStrLine::SetWMatrix(const Double_t *wmat) {
	166	// Setter for weighting matrix, strating from a [9] dim. array
	167	if(fWMatrix)delete [] fWMatrix;
	168	fWMatrix = new Double_t [6];
	169	Int_t k = 0;
	170	for(Int_t i=0;i<3;i++){
	171	for(Int_t j=0;j<3;j++)if(j>=i)fWMatrix[k++]=wmat[3*i+j];
	172	}
	173	}
	174
	175	//________________________________________________________
	176	void AliStrLine::InitDirection(const Double_t const point, const Double_t const cd)
	177	{
	178	// Initialization from a point and a direction
	179	Double_t norm = cd[0]cd[0]+cd[1]cd[1]+cd[2]*cd[2];
	180
	181	if(norm) {
	182	norm = TMath::Sqrt(1./norm);
	183	for(Int_t i=0;i<3;++i) {
	184	fP0[i]=point[i];
	185	fCd[i]=cd[i]*norm;
	186	}
	187	fTpar = 0.;
	188	}
	189	else AliFatal("Null direction cosines!!!");
	190	}
	191
	192	//________________________________________________________
	193	void AliStrLine::InitTwoPoints(const Double_t const pA, const Double_t const pB)
	194	{
	195	// Initialization from the coordinates of two
	196	// points in the space
	197	Double_t cd[3];
	198	for(Int_t i=0;i<3;i++)cd[i] = pB[i]-pA[i];
	199	InitDirection(pA,cd);
	200	}
	201
	202	//________________________________________________________
	203	AliStrLine::~AliStrLine() {
	204	// destructor
	205	if(fWMatrix)delete [] fWMatrix;
	206	}
	207
	208	//________________________________________________________
	209	void AliStrLine::PrintStatus() const {
	210	// Print current status
	211	cout <<"=======================================================\n";
	212	cout <<"Direction cosines: ";
	213	for(Int_t i=0;i<3;i++)cout <<fCd[i]<<"; ";
	214	cout <<endl;
	215	cout <<"Known point: ";
	216	for(Int_t i=0;i<3;i++)cout <<fP0[i]<<"; ";
	217	cout <<endl;
	218	cout <<"Error on known point: ";
	219	for(Int_t i=0;i<3;i++)cout <<TMath::Sqrt(fSigma2P0[i])<<"; ";
	220	cout <<endl;
	221	cout <<"Current value for the parameter: "<<fTpar<<endl;
	222	}
	223
	224	//________________________________________________________
	225	Int_t AliStrLine::IsParallelTo(const AliStrLine *line) const {
	226	// returns 1 if lines are parallel, 0 if not paralel
	227	const Double_t prec=1e-14;
	228	Double_t cd2[3];
	229	line->GetCd(cd2);
	230
	231	Double_t vecpx=fCd[1]cd2[2]-fCd[2]cd2[1];
	232	Double_t mod=TMath::Abs(fCd[1]cd2[2])+TMath::Abs(fCd[2]cd2[1]);
	233	if(TMath::Abs(vecpx) > prec*mod) return 0;
	234
	235	Double_t vecpy=-fCd[0]cd2[2]+fCd[2]cd2[0];
	236	mod=TMath::Abs(fCd[0]cd2[2])+TMath::Abs(fCd[2]cd2[0]);
	237	if(TMath::Abs(vecpy) > prec*mod) return 0;
	238
	239	Double_t vecpz=fCd[0]cd2[1]-fCd[1]cd2[0];
	240	mod=TMath::Abs(fCd[0]cd2[1])+TMath::Abs(fCd[1]cd2[0]);
	241	if(TMath::Abs(vecpz) > prec) return 0;
	242
	243	return 1;
	244	}
	245	//________________________________________________________
	246	Int_t AliStrLine::Crossrphi(const AliStrLine *line)
	247	{
	248	// Cross 2 lines in the X-Y plane
	249	const Double_t prec=1e-14;
	250	const Double_t big=1e20;
	251	Double_t p2[3];
	252	Double_t cd2[3];
	253	line->GetP0(p2);
	254	line->GetCd(cd2);
	255	Double_t a=fCd[0];
	256	Double_t b=-cd2[0];
	257	Double_t c=p2[0]-fP0[0];
	258	Double_t d=fCd[1];
	259	Double_t e=-cd2[1];
	260	Double_t f=p2[1]-fP0[1];
	261	Double_t deno = ae-bd;
	262	Double_t mod=TMath::Abs(ae)+TMath::Abs(bd);
	263	Int_t retcode = 0;
	264	if(TMath::Abs(deno) > prec*mod) {
	265	fTpar = (ce-bf)/deno;
	266	}
	267	else {
	268	fTpar = big;
	269	retcode = -1;
	270	}
	271	return retcode;
	272	}
	273
	274	//________________________________________________________
	275	Int_t AliStrLine::CrossPoints(AliStrLine line, Double_t point1, Double_t *point2){
	276	// Looks for the crossing point estimated starting from the
	277	// DCA segment
	278	const Double_t prec=1e-14;
	279	Double_t p2[3];
	280	Double_t cd2[3];
	281	line->GetP0(p2);
	282	line->GetCd(cd2);
	283	Int_t i;
	284	Double_t k1 = 0;
	285	Double_t k2 = 0;
	286	Double_t a11 = 0;
	287	for(i=0;i<3;i++){
	288	k1+=(fP0[i]-p2[i])*fCd[i];
	289	k2+=(fP0[i]-p2[i])*cd2[i];
	290	a11+=fCd[i]*cd2[i];
	291	}
	292	Double_t a22 = -a11;
	293	Double_t a21 = 0;
	294	Double_t a12 = 0;
	295	for(i=0;i<3;i++){
	296	a21+=cd2[i]*cd2[i];
	297	a12-=fCd[i]*fCd[i];
	298	}
	299	Double_t deno = a11a22-a21a12;
	300	Double_t mod = TMath::Abs(a11a22)+TMath::Abs(a21a12);
	301	if(TMath::Abs(deno) < prec*mod) return -1;
	302	fTpar = (a11k2-a21k1) / deno;
	303	Double_t par2 = (k1a22-k2a12) / deno;
	304	line->SetPar(par2);
	305	GetCurrentPoint(point1);
	306	line->GetCurrentPoint(point2);
	307	return 0;
	308	}
	309	//________________________________________________________________
	310	Int_t AliStrLine::Cross(AliStrLine line, Double_t point)
	311	{
	312
	313	//Finds intersection between lines
	314	Double_t point1[3];
	315	Double_t point2[3];
	316	Int_t retcod=CrossPoints(line,point1,point2);
	317	if(retcod==0){
	318	for(Int_t i=0;i<3;i++)point[i]=(point1[i]+point2[i])/2.;
	319	return 0;
	320	}else{
	321	return -1;
	322	}
	323	}
	324
	325	//___________________________________________________________
	326	Double_t AliStrLine::GetDCA(const AliStrLine *line) const
	327	{
	328	//Returns the distance of closest approach between two lines
	329	const Double_t prec=1e-14;
	330	Double_t p2[3];
	331	Double_t cd2[3];
	332	line->GetP0(p2);
	333	line->GetCd(cd2);
	334	Int_t i;
	335	Int_t ispar=IsParallelTo(line);
	336	if(ispar){
	337	Double_t dist1q=0,dist2=0,mod=0;
	338	for(i=0;i<3;i++){
	339	dist1q+=(fP0[i]-p2[i])*(fP0[i]-p2[i]);
	340	dist2+=(fP0[i]-p2[i])*fCd[i];
	341	mod+=fCd[i]*fCd[i];
	342	}
	343	if(TMath::Abs(mod) > prec){
	344	dist2/=mod;
	345	return TMath::Sqrt(dist1q-dist2*dist2);
	346	}else{return -1;}
	347	}else{
	348	Double_t perp[3];
	349	perp[0]=fCd[1]cd2[2]-fCd[2]cd2[1];
	350	perp[1]=-fCd[0]cd2[2]+fCd[2]cd2[0];
	351	perp[2]=fCd[0]cd2[1]-fCd[1]cd2[0];
	352	Double_t mod=0,dist=0;
	353	for(i=0;i<3;i++){
	354	mod+=perp[i]*perp[i];
	355	dist+=(fP0[i]-p2[i])*perp[i];
	356	}
	357	if(TMath::Abs(mod) > prec) {
	358	return TMath::Abs(dist/TMath::Sqrt(mod));
	359	} else return -1;
	360	}
	361	}
	362	//________________________________________________________
	363	void AliStrLine::GetCurrentPoint(Double_t *point) const {
	364	// Fills the array point with the current value on the line
	365	for(Int_t i=0;i<3;i++)point[i]=fP0[i]+fCd[i]*fTpar;
	366	}
	367
	368	//________________________________________________________
	369	Double_t AliStrLine::GetDistFromPoint(const Double_t *point) const
	370	{
	371	// computes distance from point
	372	AliStrLine tmpline(point, fCd, kFALSE);
	373	return GetDCA(&tmpline);
	374	}