From 67178f341a0b0808fc488f31ff7d771aed38bb94 Mon Sep 17 00:00:00 2001
From: masera <masera@f7af4fe6-9843-0410-8265-dc069ae4e863>
Date: Wed, 1 Jul 2009 08:25:45 +0000
Subject: [PATCH] Added speed-up and protection suggested by Ruben in Savannah
 #48080

---
 ITS/AliITStrackerMI.cxx | 25 +++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/ITS/AliITStrackerMI.cxx b/ITS/AliITStrackerMI.cxx
index 996b08d1c20..f52a7ee95a2 100644
--- a/ITS/AliITStrackerMI.cxx
+++ b/ITS/AliITStrackerMI.cxx
@@ -658,7 +658,7 @@ Int_t AliITStrackerMI::PropagateBack(AliESDEvent *event) {
      t->SetExpQ(TMath::Max(0.8*t->GetESDtrack()->GetTPCsignal(),30.));
 
      ResetTrackToFollow(*t);
-
+     /*
      // propagate to vertex [SR, GSI 17.02.2003]
      // Start Time measurement [SR, GSI 17.02.2003], corrected by I.Belikov
      if (CorrectForPipeMaterial(&fTrackToFollow,"inward")) {
@@ -666,7 +666,17 @@ Int_t AliITStrackerMI::PropagateBack(AliESDEvent *event) {
 	 fTrackToFollow.StartTimeIntegral();
        // from vertex to outside pipe
        CorrectForPipeMaterial(&fTrackToFollow,"outward");
+       }*/
+     // Start time integral and add distance from current position to vertex 
+     Double_t xyzTrk[3],xyzVtx[3]={GetX(),GetY(),GetZ()};
+     fTrackToFollow.GetXYZ(xyzTrk);
+     Double_t dst2 = 0.;
+     for (Int_t icoord=0; icoord<3; icoord++) {  
+       Double_t di = xyzTrk[icoord] - xyzVtx[icoord];
+       dst2 += di*di; 
      }
+     fTrackToFollow.StartTimeIntegral();
+     fTrackToFollow.AddTimeStep(TMath::Sqrt(dst2));
 
      fTrackToFollow.ResetCovariance(10.); fTrackToFollow.ResetClusters();
      if (RefitAt(AliITSRecoParam::GetrInsideITSscreen(),&fTrackToFollow,t)) {
@@ -2221,6 +2231,11 @@ Bool_t AliITStrackerMI::RefitAt(Double_t xx,AliITStrackMI *track,
      Double_t oldGlobXYZ[3];
      if (!track->GetXYZ(oldGlobXYZ)) return kFALSE;
 
+     // continue if we are already beyond this layer
+     Double_t oldGlobR = TMath::Sqrt(oldGlobXYZ[0]*oldGlobXYZ[0]+oldGlobXYZ[1]*oldGlobXYZ[1]);
+     if(step>0 && oldGlobR > r) continue; // going outward
+     if(step<0 && oldGlobR < r) continue; // going inward
+
      Double_t phi,z;
      if (!track->GetPhiZat(r,phi,z)) return kFALSE;
 
@@ -3999,6 +4014,13 @@ Int_t AliITStrackerMI::CorrectForShieldMaterial(AliITStrackMI *t,
     Error("CorrectForShieldMaterial"," Wrong shield name\n");
     return 0;
   }
+
+  // do nothing if we are already beyond the shield
+  Double_t rTrack = TMath::Sqrt(t->GetX()*t->GetX()+t->GetY()*t->GetY());
+  if(dir<0 && rTrack > rToGo) return 1; // going outward
+  if(dir>0 && rTrack < rToGo) return 1; // going inward
+
+
   Double_t xToGo;
   if (!t->GetLocalXat(rToGo,xToGo)) return 0;
 
@@ -4648,4 +4670,3 @@ void AliITStrackerMI::UseTrackForPlaneEff(const AliITStrackMI* track, Int_t ilay
   }
 return;
 }
-
-- 
2.43.0