diff --git a/ClassAnasen.h b/ClassAnasen.h
new file mode 100644
index 0000000..55d4393
--- /dev/null
+++ b/ClassAnasen.h
@@ -0,0 +1,90 @@
+#ifndef ClassAnasen_h
+#define ClassAnasen_h
+
+#include <cstdio>
+#include <TMath.h>
+#include <TVector3.h>
+
+class Anasen{
+public:
+  Anasen();
+  ~Anasen() {}
+
+  void CalTrack(TVector3 sx3Pos, int anodeID, int cathodeID);
+
+  TVector3 GetTrackPos() const {return trackPos;}
+  TVector3 GetTrackVec() const {return trackVec;}
+
+  double GetTrackTheta() const {return trackVec.Theta();}
+  double GetTrackPhi()   const {return trackVec.Phi();}
+
+  // void DrawTrack();
+
+private:
+
+  const int nWire = 24;
+  const int wireShift = 3; // how twisted is the wire.
+  const double AnodeRadius = 38 ; // mm
+  const double CathodeRadius = 38 ; // mm
+  const double PCLength = 100; //mm
+
+  std::vector<TVector3> AnodeN; // the anode wire direction vector in space 
+  std::vector<TVector3> CathodeN; // the cathode wire direction vector in space 
+
+  void CalWireDirection();
+
+  TVector3 trackPos;
+  TVector3 trackVec;
+
+  double trackPosErrorZ;  // mm
+  TVector3 tracePosErrorXY; // the mag is the size of the error
+
+  TVector3 trackVecErrorA; // error vector prependicular to the Anode-Pos plan
+  TVector3 trackVecErrorC; // error vector prependicular to the Cathode-Pos plan
+
+};
+
+inline Anasen::Anasen(){
+
+  CalWireDirection();
+
+}
+
+inline void Anasen::CalWireDirection(){
+
+  TVector3 P1; // anode
+  TVector3 P2;
+  TVector3 Q1; // cathode
+  TVector3 Q2;
+  for(int i = 0; i < nWire; i++ ){
+    P1.SetXYZ( AnodeRadius * TMath::Cos( TMath::TwoPi() * i / nWire ),
+               AnodeRadius * TMath::Sin( TMath::TwoPi() * i / nWire ),
+               -PCLength/2);
+    P2.SetXYZ( AnodeRadius * TMath::Cos( TMath::TwoPi() * (i + wireShift) / nWire ),
+               AnodeRadius * TMath::Sin( TMath::TwoPi() * (i + wireShift) / nWire ),
+               PCLength/2);
+    AnodeN.push_back((P2 - P1).Unit());
+
+    Q1.SetXYZ( CathodeRadius * TMath::Cos( TMath::TwoPi() * i / nWire ),
+               CathodeRadius * TMath::Sin( TMath::TwoPi() * i / nWire ),
+               -PCLength/2);
+    Q2.SetXYZ( CathodeRadius * TMath::Cos( TMath::TwoPi() * (i - wireShift) / nWire ),
+               CathodeRadius * TMath::Sin( TMath::TwoPi() * (i - wireShift) / nWire ),
+               PCLength/2);
+    CathodeN.push_back((Q2 - Q1).Unit());
+  }
+
+}
+
+inline void Anasen::CalTrack(TVector3 sx3Pos, int anodeID, int cathodeID){
+
+  trackPos = sx3Pos;
+
+  TVector3 n1 = AnodeN[anodeID].Cross(sx3Pos);
+  TVector3 n2 = CathodeN[cathodeID].Cross(sx3Pos);
+
+  trackVec = (n1.Cross(n2)).Unit();
+
+}
+
+#endif 
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