[u/mrichter/AliRoot.git] / STEER / AliTracker.cxx

/**************************************************************************
 * Copyright(c) 1998-1999, 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.                  *
 **************************************************************************/

/* $Id$ */

//-------------------------------------------------------------------------
//               Implementation of the AliTracker class
//  that is the base for AliTPCtracker, AliITStrackerV2 and AliTRDtracker    
//        Origin: Iouri Belikov, CERN, Jouri.Belikov@cern.ch
//-------------------------------------------------------------------------
#include <TClass.h>
#include <TMath.h>
#include <TGeoManager.h>

#include "AliMagF.h"
#include "AliTracker.h"
#include "AliCluster.h"
#include "AliKalmanTrack.h"

extern TGeoManager *gGeoManager;

Bool_t AliTracker::fgUniformField=kTRUE;
Double_t AliTracker::fgBz=kAlmost0Field;
const AliMagF *AliTracker::fgkFieldMap=0;

ClassImp(AliTracker)

AliTracker::AliTracker():
  TObject(),
  fX(0),
  fY(0),
  fZ(0),
  fSigmaX(0.005),
  fSigmaY(0.005),
  fSigmaZ(0.010)
{
  //--------------------------------------------------------------------
  // The default constructor.
  //--------------------------------------------------------------------
  if (!fgkFieldMap) AliWarning("Field map is not set. Call AliTracker::SetFieldMap before creating a tracker!");
}

//__________________________________________________________________________
AliTracker::AliTracker(const AliTracker &atr):
  TObject(atr),
  fX(atr.fX),
  fY(atr.fY),
  fZ(atr.fZ),
  fSigmaX(atr.fSigmaX),
  fSigmaY(atr.fSigmaY),
  fSigmaZ(atr.fSigmaZ)
{
  //--------------------------------------------------------------------
  // The default constructor.
  //--------------------------------------------------------------------
  if (!fgkFieldMap) AliWarning("Field map is not set. Call AliTracker::SetFieldMap before creating a tracker!");
}

//__________________________________________________________________________
void AliTracker::SetFieldMap(const AliMagF* map, Bool_t uni) {
  //--------------------------------------------------------------------
  //This passes the field map to the reconstruction.
  //--------------------------------------------------------------------
  if (map==0) AliFatalClass("Can't access the field map !");

  if (fgkFieldMap) {
     AliWarningClass("The magnetic field map has been already set !");
     return;
  }

  fgUniformField=uni;
  fgkFieldMap=map;

  //Float_t r[3]={0.,0.,0.},b[3]; map->Field(r,b);
  //Double_t bz=-b[2];
 
  Double_t bz=-map->SolenoidField();
  fgBz=TMath::Sign(kAlmost0Field,bz) + bz;

}

//__________________________________________________________________________
void AliTracker::CookLabel(AliKalmanTrack *t, Float_t wrong) const {
  //--------------------------------------------------------------------
  //This function "cooks" a track label. If label<0, this track is fake.
  //--------------------------------------------------------------------
  Int_t noc=t->GetNumberOfClusters();
  Int_t *lb=new Int_t[noc];
  Int_t *mx=new Int_t[noc];
  AliCluster **clusters=new AliCluster*[noc];

  Int_t i;
  for (i=0; i<noc; i++) {
     lb[i]=mx[i]=0;
     Int_t index=t->GetClusterIndex(i);
     clusters[i]=GetCluster(index);
  }

  Int_t lab=123456789;
  for (i=0; i<noc; i++) {
    AliCluster *c=clusters[i];
    lab=TMath::Abs(c->GetLabel(0));
    Int_t j;
    for (j=0; j<noc; j++) if (lb[j]==lab || mx[j]==0) break;
    lb[j]=lab;
    (mx[j])++;
  }

  Int_t max=0;
  for (i=0; i<noc; i++) if (mx[i]>max) {max=mx[i]; lab=lb[i];}
    
  for (i=0; i<noc; i++) {
    AliCluster *c=clusters[i];
    //if (TMath::Abs(c->GetLabel(1)) == lab ||
    //    TMath::Abs(c->GetLabel(2)) == lab ) max++;
    if (TMath::Abs(c->GetLabel(0)!=lab))
	if (TMath::Abs(c->GetLabel(1)) == lab ||
	    TMath::Abs(c->GetLabel(2)) == lab ) max++;
  }

  if ((1.- Float_t(max)/noc) > wrong) lab=-lab;
  t->SetFakeRatio((1.- Float_t(max)/noc));
  t->SetLabel(lab);

  delete[] lb;
  delete[] mx;
  delete[] clusters;
}

//____________________________________________________________________________
void AliTracker::UseClusters(const AliKalmanTrack *t, Int_t from) const {
  //------------------------------------------------------------------
  //This function marks clusters associated with the track.
  //------------------------------------------------------------------
  Int_t noc=t->GetNumberOfClusters();
  for (Int_t i=from; i<noc; i++) {
     Int_t index=t->GetClusterIndex(i);
     AliCluster *c=GetCluster(index); 
     c->Use();   
  }
}

Double_t AliTracker::GetBz(Float_t *r) {
  //------------------------------------------------------------------
  // Returns Bz (kG) at the point "r" .
  //------------------------------------------------------------------
    Float_t b[3]; fgkFieldMap->Field(r,b);
    Double_t bz=-Double_t(b[2]);
    return  (TMath::Sign(kAlmost0Field,bz) + bz);
}

Double_t 
AliTracker::MeanMaterialBudget(Double_t *start,Double_t *end,Double_t *mparam)
{
  // 
  // Calculate mean material budget and material properties between 
  //    the points "start" and "end".
  //
  // "mparam" - parameters used for the energy and multiple scattering
  //  corrections: 
  //
  // mparam[0] - mean density: sum(x_i*rho_i)/sum(x_i) [g/cm3]
  // mparam[1] - equivalent rad length fraction: sum(x_i/X0_i) [adimensional]
  // mparam[2] - mean A: sum(x_i*A_i)/sum(x_i) [adimensional]
  // mparam[3] - mean Z: sum(x_i*Z_i)/sum(x_i) [adimensional]
  // mparam[4] - length: sum(x_i) [cm]
  // mparam[5] - Z/A mean: sum(x_i*Z_i/A_i)/sum(x_i) [adimensional]
  // mparam[6] - number of boundary crosses
  //

  mparam[0]=0; mparam[1]=1; mparam[2] =0; mparam[3] =0;
  mparam[4]=0; mparam[5]=0; mparam[6]=0;
  //
  Double_t bparam[6]; // total parameters
  Double_t lparam[6]; // local parameters

  for (Int_t i=0;i<6;i++) bparam[i]=0;

  if (!gGeoManager) {
    printf("ERROR: no TGeo\n");
    return 0.;
  }
  //
  Double_t length;
  Double_t dir[3];
  length = TMath::Sqrt((end[0]-start[0])*(end[0]-start[0])+
                       (end[1]-start[1])*(end[1]-start[1])+
                       (end[2]-start[2])*(end[2]-start[2]));
  mparam[4]=length;
  if (length<TGeoShape::Tolerance()) return 0.0;
  Double_t invlen = 1./length;
  dir[0] = (end[0]-start[0])*invlen;
  dir[1] = (end[1]-start[1])*invlen;
  dir[2] = (end[2]-start[2])*invlen;

  // Initialize start point and direction
  TGeoNode *currentnode = 0;
  TGeoNode *startnode = gGeoManager->InitTrack(start, dir);
  //printf("%s length=%f\n",gGeoManager->GetPath(),length);
  if (!startnode) {
    printf("ERROR: start point out of geometry\n");
    return 0.0;
  }
  TGeoMaterial *material = startnode->GetVolume()->GetMedium()->GetMaterial();
  lparam[0]   = material->GetDensity();
  lparam[1]   = material->GetRadLen();
  lparam[2]   = material->GetA();
  lparam[3]   = material->GetZ();
  lparam[4]   = length;
  lparam[5]   = lparam[3]/lparam[2];
  if (material->IsMixture()) {
    TGeoMixture * mixture = (TGeoMixture*)material;
    lparam[5] =0;
    Double_t sum =0;
    for (Int_t iel=0;iel<mixture->GetNelements();iel++){
      sum  += mixture->GetWmixt()[iel];
      lparam[5]+= mixture->GetZmixt()[iel]*mixture->GetWmixt()[iel]/mixture->GetAmixt()[iel];
    }
    lparam[5]/=sum;
  }

  // Locate next boundary within length without computing safety.
  // Propagate either with length (if no boundary found) or just cross boundary
  gGeoManager->FindNextBoundaryAndStep(length, kFALSE);
  Double_t step = 0.0; // Step made
  Double_t snext = gGeoManager->GetStep();
  // If no boundary within proposed length, return current density
  if (!gGeoManager->IsOnBoundary()) {
    mparam[0] = lparam[0];
    mparam[1] = lparam[4]/lparam[1];
    mparam[2] = lparam[2];
    mparam[3] = lparam[3];
    mparam[4] = lparam[4];
    return lparam[0];
  }
  // Try to cross the boundary and see what is next
  Int_t nzero = 0;
  while (length>TGeoShape::Tolerance()) {
    currentnode = gGeoManager->GetCurrentNode();
    if (snext<2.*TGeoShape::Tolerance()) nzero++;
    else nzero = 0;
    if (nzero>3) {
      // This means navigation has problems on one boundary
      // Try to cross by making a small step
      printf("ERROR: cannot cross boundary\n");
      mparam[0] = bparam[0]/step;
      mparam[1] = bparam[1];
      mparam[2] = bparam[2]/step;
      mparam[3] = bparam[3]/step;
      mparam[5] = bparam[5]/step;
      mparam[4] = step;
      mparam[0] = 0.;             // if crash of navigation take mean density 0
      mparam[1] = 1000000;        // and infinite rad length
      return bparam[0]/step;
    }
    mparam[6]+=1.;
    step += snext;
    bparam[1]    += snext/lparam[1];
    bparam[2]    += snext*lparam[2];
    bparam[3]    += snext*lparam[3];
    bparam[5]    += snext*lparam[5];
    bparam[0]    += snext*lparam[0];

    if (snext>=length) break;
    if (!currentnode) break;
    length -= snext;
    //printf("%s snext=%f length=%f\n", currentnode->GetName(),snext,length);
    material = currentnode->GetVolume()->GetMedium()->GetMaterial();
    lparam[0] = material->GetDensity();
    lparam[1]  = material->GetRadLen();
    lparam[2]  = material->GetA();
    lparam[3]  = material->GetZ();
    //printf("       %f %f %f %f\n",lparam[0],lparam[1],lparam[2],lparam[3]); 
    lparam[5]   = lparam[3]/lparam[2];
    if (material->IsMixture()) {
      TGeoMixture * mixture = (TGeoMixture*)material;
      lparam[5]=0;
      Double_t sum =0;
      for (Int_t iel=0;iel<mixture->GetNelements();iel++){
        sum+= mixture->GetWmixt()[iel];
        lparam[5]+= mixture->GetZmixt()[iel]*mixture->GetWmixt()[iel]/mixture->GetAmixt()[iel];
      }
      lparam[5]/=sum;
    }
    gGeoManager->FindNextBoundaryAndStep(length, kFALSE);
    snext = gGeoManager->GetStep();
    //printf("snext %f\n",snext);
  }
  mparam[0] = bparam[0]/step;
  mparam[1] = bparam[1];
  mparam[2] = bparam[2]/step;
  mparam[3] = bparam[3]/step;
  mparam[5] = bparam[5]/step;
  return bparam[0]/step;
}
Commit	Line	Data
be9c5115	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
acd84897	16	/* $Id$ */
fb17acd4	17
be9c5115	18	//-------------------------------------------------------------------------
be9c5115	19	// Implementation of the AliTracker class
9b83b8cc	20	// that is the base for AliTPCtracker, AliITStrackerV2 and AliTRDtracker
9b83b8cc	21	// Origin: Iouri Belikov, CERN, Jouri.Belikov@cern.ch
be9c5115	22	//-------------------------------------------------------------------------
7d0f8548	23	#include <TClass.h>
be9c5115	24	#include <TMath.h>
6e440ee5	25	#include <TGeoManager.h>
be9c5115	26
7b5ef2e6	27	#include "AliMagF.h"
be9c5115	28	#include "AliTracker.h"
c84a5e9e	29	#include "AliCluster.h"
7d0f8548	30	#include "AliKalmanTrack.h"
41377c29	31
6e440ee5	32	extern TGeoManager *gGeoManager;
6e440ee5	33
7d0f8548	34	Bool_t AliTracker::fgUniformField=kTRUE;
7b5ef2e6	35	Double_t AliTracker::fgBz=kAlmost0Field;
3b242889	36	const AliMagF *AliTracker::fgkFieldMap=0;
3b242889	37
be9c5115	38	ClassImp(AliTracker)
be9c5115	39
3b242889	40	AliTracker::AliTracker():
fe12e09c	41	TObject(),
3b242889	42	fX(0),
	43	fY(0),
	44	fZ(0),
	45	fSigmaX(0.005),
	46	fSigmaY(0.005),
	47	fSigmaZ(0.010)
	48	{
	49	//--------------------------------------------------------------------
	50	// The default constructor.
	51	//--------------------------------------------------------------------
c9b9861a	52	if (!fgkFieldMap) AliWarning("Field map is not set. Call AliTracker::SetFieldMap before creating a tracker!");
3b242889	53	}
3b242889	54
fe12e09c	55	//__________________________________________________________________________
	56	AliTracker::AliTracker(const AliTracker &atr):
	57	TObject(atr),
	58	fX(atr.fX),
	59	fY(atr.fY),
	60	fZ(atr.fZ),
	61	fSigmaX(atr.fSigmaX),
	62	fSigmaY(atr.fSigmaY),
	63	fSigmaZ(atr.fSigmaZ)
	64	{
	65	//--------------------------------------------------------------------
	66	// The default constructor.
	67	//--------------------------------------------------------------------
	68	if (!fgkFieldMap) AliWarning("Field map is not set. Call AliTracker::SetFieldMap before creating a tracker!");
	69	}
	70
	71	//__________________________________________________________________________
7d0f8548	72	void AliTracker::SetFieldMap(const AliMagF* map, Bool_t uni) {
	73	//--------------------------------------------------------------------
	74	//This passes the field map to the reconstruction.
	75	//--------------------------------------------------------------------
	76	if (map==0) AliFatalClass("Can't access the field map !");
	77
729c2fa2	78	if (fgkFieldMap) {
	79	AliWarningClass("The magnetic field map has been already set !");
	80	return;
	81	}
	82
7d0f8548	83	fgUniformField=uni;
	84	fgkFieldMap=map;
	85
	86	//Float_t r[3]={0.,0.,0.},b[3]; map->Field(r,b);
7ebb06c3	87	//Double_t bz=-b[2];
7d0f8548	88
7ebb06c3	89	Double_t bz=-map->SolenoidField();
7b5ef2e6	90	fgBz=TMath::Sign(kAlmost0Field,bz) + bz;
7d0f8548	91
	92	}
	93
be9c5115	94	//__________________________________________________________________________
	95	void AliTracker::CookLabel(AliKalmanTrack *t, Float_t wrong) const {
	96	//--------------------------------------------------------------------
	97	//This function "cooks" a track label. If label<0, this track is fake.
	98	//--------------------------------------------------------------------
	99	Int_t noc=t->GetNumberOfClusters();
	100	Int_t *lb=new Int_t[noc];
	101	Int_t *mx=new Int_t[noc];
	102	AliCluster *clusters=new AliCluster[noc];
	103
	104	Int_t i;
	105	for (i=0; i<noc; i++) {
	106	lb[i]=mx[i]=0;
	107	Int_t index=t->GetClusterIndex(i);
	108	clusters[i]=GetCluster(index);
	109	}
	110
	111	Int_t lab=123456789;
	112	for (i=0; i<noc; i++) {
	113	AliCluster *c=clusters[i];
	114	lab=TMath::Abs(c->GetLabel(0));
	115	Int_t j;
	116	for (j=0; j<noc; j++) if (lb[j]==lab \|\| mx[j]==0) break;
	117	lb[j]=lab;
	118	(mx[j])++;
	119	}
	120
	121	Int_t max=0;
	122	for (i=0; i<noc; i++) if (mx[i]>max) {max=mx[i]; lab=lb[i];}
	123
	124	for (i=0; i<noc; i++) {
	125	AliCluster *c=clusters[i];
babd135a	126	//if (TMath::Abs(c->GetLabel(1)) == lab \|\|
	127	// TMath::Abs(c->GetLabel(2)) == lab ) max++;
	128	if (TMath::Abs(c->GetLabel(0)!=lab))
	129	if (TMath::Abs(c->GetLabel(1)) == lab \|\|
	130	TMath::Abs(c->GetLabel(2)) == lab ) max++;
be9c5115	131	}
	132
	133	if ((1.- Float_t(max)/noc) > wrong) lab=-lab;
babd135a	134	t->SetFakeRatio((1.- Float_t(max)/noc));
be9c5115	135	t->SetLabel(lab);
	136
	137	delete[] lb;
	138	delete[] mx;
	139	delete[] clusters;
	140	}
	141
	142	//____________________________________________________________________________
	143	void AliTracker::UseClusters(const AliKalmanTrack *t, Int_t from) const {
	144	//------------------------------------------------------------------
	145	//This function marks clusters associated with the track.
	146	//------------------------------------------------------------------
	147	Int_t noc=t->GetNumberOfClusters();
	148	for (Int_t i=from; i<noc; i++) {
	149	Int_t index=t->GetClusterIndex(i);
	150	AliCluster *c=GetCluster(index);
	151	c->Use();
	152	}
	153	}
7b5ef2e6	154
	155	Double_t AliTracker::GetBz(Float_t *r) {
	156	//------------------------------------------------------------------
	157	// Returns Bz (kG) at the point "r" .
	158	//------------------------------------------------------------------
	159	Float_t b[3]; fgkFieldMap->Field(r,b);
	160	Double_t bz=-Double_t(b[2]);
	161	return (TMath::Sign(kAlmost0Field,bz) + bz);
	162	}
6e440ee5	163
	164	Double_t
	165	AliTracker::MeanMaterialBudget(Double_t start,Double_t end,Double_t *mparam)
	166	{
	167	//
	168	// Calculate mean material budget and material properties between
	169	// the points "start" and "end".
	170	//
	171	// "mparam" - parameters used for the energy and multiple scattering
	172	// corrections:
	173	//
	174	// mparam[0] - mean density: sum(x_i*rho_i)/sum(x_i) [g/cm3]
	175	// mparam[1] - equivalent rad length fraction: sum(x_i/X0_i) [adimensional]
	176	// mparam[2] - mean A: sum(x_i*A_i)/sum(x_i) [adimensional]
	177	// mparam[3] - mean Z: sum(x_i*Z_i)/sum(x_i) [adimensional]
	178	// mparam[4] - length: sum(x_i) [cm]
	179	// mparam[5] - Z/A mean: sum(x_i*Z_i/A_i)/sum(x_i) [adimensional]
	180	// mparam[6] - number of boundary crosses
	181	//
	182
	183	mparam[0]=0; mparam[1]=1; mparam[2] =0; mparam[3] =0;
	184	mparam[4]=0; mparam[5]=0; mparam[6]=0;
	185	//
	186	Double_t bparam[6]; // total parameters
	187	Double_t lparam[6]; // local parameters
	188
	189	for (Int_t i=0;i<6;i++) bparam[i]=0;
	190
	191	if (!gGeoManager) {
	192	printf("ERROR: no TGeo\n");
	193	return 0.;
	194	}
	195	//
	196	Double_t length;
	197	Double_t dir[3];
	198	length = TMath::Sqrt((end[0]-start[0])*(end[0]-start[0])+
	199	(end[1]-start[1])*(end[1]-start[1])+
	200	(end[2]-start[2])*(end[2]-start[2]));
	201	mparam[4]=length;
	202	if (length<TGeoShape::Tolerance()) return 0.0;
	203	Double_t invlen = 1./length;
	204	dir[0] = (end[0]-start[0])*invlen;
	205	dir[1] = (end[1]-start[1])*invlen;
	206	dir[2] = (end[2]-start[2])*invlen;
	207
	208	// Initialize start point and direction
	209	TGeoNode *currentnode = 0;
	210	TGeoNode *startnode = gGeoManager->InitTrack(start, dir);
	211	//printf("%s length=%f\n",gGeoManager->GetPath(),length);
	212	if (!startnode) {
	213	printf("ERROR: start point out of geometry\n");
	214	return 0.0;
	215	}
	216	TGeoMaterial *material = startnode->GetVolume()->GetMedium()->GetMaterial();
	217	lparam[0] = material->GetDensity();
	218	lparam[1] = material->GetRadLen();
	219	lparam[2] = material->GetA();
	220	lparam[3] = material->GetZ();
	221	lparam[4] = length;
	222	lparam[5] = lparam[3]/lparam[2];
	223	if (material->IsMixture()) {
	224	TGeoMixture * mixture = (TGeoMixture*)material;
	225	lparam[5] =0;
	226	Double_t sum =0;
227	for (Int_t iel=0;iel<mixture->GetNelements();iel++){
228	sum += mixture->GetWmixt()[iel];
229	lparam[5]+= mixture->GetZmixt()[iel]*mixture->GetWmixt()[iel]/mixture->GetAmixt()[iel];
230	}
231	lparam[5]/=sum;
232	}
233
234	// Locate next boundary within length without computing safety.
235	// Propagate either with length (if no boundary found) or just cross boundary
236	gGeoManager->FindNextBoundaryAndStep(length, kFALSE);
237	Double_t step = 0.0; // Step made
238	Double_t snext = gGeoManager->GetStep();
239	// If no boundary within proposed length, return current density
240	if (!gGeoManager->IsOnBoundary()) {
241	mparam[0] = lparam[0];
242	mparam[1] = lparam[4]/lparam[1];
243	mparam[2] = lparam[2];
244	mparam[3] = lparam[3];
245	mparam[4] = lparam[4];
246	return lparam[0];
247	}
248	// Try to cross the boundary and see what is next
249	Int_t nzero = 0;
250	while (length>TGeoShape::Tolerance()) {
251	currentnode = gGeoManager->GetCurrentNode();
252	if (snext<2.*TGeoShape::Tolerance()) nzero++;
253	else nzero = 0;
254	if (nzero>3) {
255	// This means navigation has problems on one boundary
256	// Try to cross by making a small step
257	printf("ERROR: cannot cross boundary\n");
258	mparam[0] = bparam[0]/step;
259	mparam[1] = bparam[1];
260	mparam[2] = bparam[2]/step;
261	mparam[3] = bparam[3]/step;
262	mparam[5] = bparam[5]/step;
263	mparam[4] = step;
264	mparam[0] = 0.; // if crash of navigation take mean density 0
265	mparam[1] = 1000000; // and infinite rad length
266	return bparam[0]/step;
267	}
268	mparam[6]+=1.;
269	step += snext;
270	bparam[1] += snext/lparam[1];
271	bparam[2] += snext*lparam[2];
272	bparam[3] += snext*lparam[3];
273	bparam[5] += snext*lparam[5];
274	bparam[0] += snext*lparam[0];
275
276	if (snext>=length) break;
277	if (!currentnode) break;
278	length -= snext;
279	//printf("%s snext=%f length=%f\n", currentnode->GetName(),snext,length);
280	material = currentnode->GetVolume()->GetMedium()->GetMaterial();
281	lparam[0] = material->GetDensity();
282	lparam[1] = material->GetRadLen();
283	lparam[2] = material->GetA();
284	lparam[3] = material->GetZ();
285	//printf(" %f %f %f %f\n",lparam[0],lparam[1],lparam[2],lparam[3]);
286	lparam[5] = lparam[3]/lparam[2];
287	if (material->IsMixture()) {
288	TGeoMixture * mixture = (TGeoMixture*)material;
289	lparam[5]=0;
290	Double_t sum =0;
291	for (Int_t iel=0;iel<mixture->GetNelements();iel++){
292	sum+= mixture->GetWmixt()[iel];
293	lparam[5]+= mixture->GetZmixt()[iel]*mixture->GetWmixt()[iel]/mixture->GetAmixt()[iel];
294	}
295	lparam[5]/=sum;
296	}
297	gGeoManager->FindNextBoundaryAndStep(length, kFALSE);
298	snext = gGeoManager->GetStep();
299	//printf("snext %f\n",snext);
300	}
301	mparam[0] = bparam[0]/step;
302	mparam[1] = bparam[1];
303	mparam[2] = bparam[2]/step;
304	mparam[3] = bparam[3]/step;
305	mparam[5] = bparam[5]/step;
306	return bparam[0]/step;
307	}