+//__________________________________________________________________________
+void AliMUONTrackExtrap::SetField(const AliMagF* magField)
+{
+ /// set magnetic field
+
+ // set field map
+ fgkField = magField;
+ if (!fgkField) {
+ cout<<"E-AliMUONTrackExtrap::SetField: fgkField = 0x0"<<endl;
+ return;
+ }
+
+ // set field on/off flag
+ fgFieldON = (fgkField->Factor() == 0.) ? kFALSE : kTRUE;
+
+ // set field at the centre of the dipole
+ if (fgFieldON) {
+ Float_t b[3] = {0.,0.,0.}, x[3] = {50.,50.,(Float_t) fgkSimpleBPosition};
+ fgkField->Field(x,b);
+ fgSimpleBValue = (Double_t) b[0];
+ } else fgSimpleBValue = 0.;
+
+}
+