From 18ecdbdf8f1fb87415e508609f287bcba8cf9987 Mon Sep 17 00:00:00 2001
From: Andrei Gheata <andrei.gheata@cern.ch>
Date: Thu, 6 Apr 2017 17:16:20 +0200
Subject: [PATCH] Fixed TGeoPGon::GetPhiCrossList for point on the Z axis.

---
 geom/geom/src/TGeoPgon.cxx | 23 +++++++++++------------
 1 file changed, 11 insertions(+), 12 deletions(-)

diff --git a/geom/geom/src/TGeoPgon.cxx b/geom/geom/src/TGeoPgon.cxx
index 1869a35bedce4..933bb99b5cdd4 100644
--- a/geom/geom/src/TGeoPgon.cxx
+++ b/geom/geom/src/TGeoPgon.cxx
@@ -540,24 +540,23 @@ Int_t TGeoPgon::GetPhiCrossList(const Double_t *point, const Double_t *dir, Int_
    if (shootorig) {
       Double_t rdotn = point[0]*dir[0]+point[1]*dir[1];
       if (rdotn>0) {
-         sphi[icrossed] = stepmax;
-         iphi[icrossed++] = istart;
-         return icrossed;
+         sphi[0] = stepmax;
+         iphi[0] = istart;
+         return 1;
       }
-      sphi[icrossed] = TMath::Sqrt((point[0]*point[0]+point[1]*point[1])/(1.-dir[2]*dir[2]));
-      iphi[icrossed++] = istart;
-      if (sphi[icrossed-1]>stepmax) {
-         sphi[icrossed-1] = stepmax;
-         return icrossed;
+      sphi[0] = TMath::Sqrt((point[0]*point[0]+point[1]*point[1])/(1.-dir[2]*dir[2]));
+      iphi[0] = istart;
+      if (sphi[0]>stepmax) {
+         sphi[0] = stepmax;
+         return 1;
       }
       phi = TMath::ATan2(dir[1], dir[0])*TMath::RadToDeg();
       while (phi<fPhi1) phi+=360.;
       istart = Int_t((phi-fPhi1)/divphi);
       if (istart>fNedges-1) istart=-1;
-      iphi[icrossed] = istart;
-      sphi[icrossed] = stepmax;
-      icrossed++;
-      return icrossed;
+      iphi[0] = istart;
+      sphi[0] = stepmax;
+      return 1;
    }
    Int_t incsec = Int_t(TMath::Sign(1., point[0]*dir[1]-point[1]*dir[0]));
    Int_t ist;