class AliCluster;
class AliKalmanTrack;
+class AliExternalTrackParam;
class AliHelix : public TObject {
public:
AliHelix();
AliHelix(const AliHelix &t);
AliHelix(const AliKalmanTrack &t);
+ AliHelix(const AliExternalTrackParam &t);
AliHelix(Double_t x[3], Double_t p[3], Double_t charge=1, Double_t conversion=0.);
virtual ~AliHelix(){};
inline void Evaluate(Double_t t, Double_t r[3]);