CurvilinearTrajectoryError.h

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#ifndef _TRACKER_CURVILINEARTRAJECTORYERROR_H_
#define _TRACKER_CURVILINEARTRAJECTORYERROR_H_

#include "DataFormats/GeometrySurface/interface/TrivialError.h"
#include "DataFormats/Math/interface/AlgebraicROOTObjects.h"
#include "DataFormats/Math/interface/Error.h"

class CurvilinearTrajectoryError {
public:

  enum { dimension = 5 };
  typedef math::Error<dimension>::type MathCovarianceMatrix;

// construct
  CurvilinearTrajectoryError() {}

  CurvilinearTrajectoryError(InvalidError) {theCovarianceMatrix(0,0)=-99999.e10;}

  CurvilinearTrajectoryError(const AlgebraicSymMatrix55& aCovarianceMatrix) :
    theCovarianceMatrix(aCovarianceMatrix) { }

  bool invalid() const { return theCovarianceMatrix(0,0)<-1.e10;}
  bool valid() const { return !invalid();}

  // not really full check of posdef
  bool posDef() const { 
    return (theCovarianceMatrix(0,0)>=0) && (theCovarianceMatrix(1,1)>=0) && 
      (theCovarianceMatrix(2,2)>=0) && (theCovarianceMatrix(3,3)>=0) && (theCovarianceMatrix(4,4)>=0);
  }


// access

  const AlgebraicSymMatrix55 &matrix() const {
    return theCovarianceMatrix;
  }

  void operator *= (double factor) {
    theCovarianceMatrix *= factor;
  }

  void zeroFieldScaling(double factor){
    double root_of_factor = sqrt(factor);
    //scale the 0 indexed covariance by the factor
    for (unsigned int i=1;i!=5;++i)      theCovarianceMatrix(i,0)*=root_of_factor;

    //scale all others by the scared factor
    for (unsigned int i=1;i!=5;++i)  for (unsigned int j=i;j!=5;++j) theCovarianceMatrix(i,j)*=factor;
    //term 0,0 is not scaled at all
  }

  operator MathCovarianceMatrix() { return theCovarianceMatrix; }
  operator const MathCovarianceMatrix &() const { return theCovarianceMatrix; }

private:
  AlgebraicSymMatrix55 theCovarianceMatrix;
};

#endif