float getCorrectedDelX(TStnMuon*  muon){

 // Generates corrected delta-x for BMU muons.

 // There is no radius-based correction here.
 // It didn't seem large enough to bother about.
 // James Bellinger	29-July-2008
  if(muon==0x0) return -9999.;
  float base=muon->BmuDelX();
  TVector3 vect;
  muon->GetBmuStubPos(vect);
  float phi=vect.Phi();
  if(phi<0) phi+=2*PI;
  int side=0;
  if(vect.Z()>0) side=1;  
  float phit=phi;
  float correction;
  if (phit>225.*PI/180.) phit = phit - 2.*PI;

  int offset;
  float zoneSlope[5]={.252545, .98351, .713636, .897813, .518677};
  float zoneInter[5]={.252016, -2.90807, -1.94013, .38034, -1.61706};
   
  offset=0;
  if(side==1 && phit<1.5707963268) offset=3;
  if(side==1 && phit>1.5707963268) offset=4;
  if(side==0 && phit>3.1415926536) offset=2;
  if(side==0 && phit>1.5707963268 && phit<3.1415926536) offset=1;
  correction = zoneSlope[offset]*phit+zoneInter[offset];

  return base - correction;
  
}