text: // g2o - General Graph Optimization
  // Copyright (C) 2011 R. Kuemmerle, G. Grisetti, H. Strasdat, W. Burgard
  // All rights reserved.
  //
  // Redistribution and use in source and binary forms, with or without
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  //
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  #ifndef G2O_BASE_EDGE_H
  #define G2O_BASE_EDGE_H
  
  #include <iostream>
  #include <limits>
  
  #include <Eigen/Core>
  
  #include "optimizable_graph.h"
  
  namespace g2o {
  
    using namespace Eigen;
  
    template <int D, typename E>
    class BaseEdge : public OptimizableGraph::Edge
    {
      public:
  
        static const int Dimension = D;
        typedef E Measurement;
        typedef Matrix<double, D, 1> ErrorVector;
        typedef Matrix<double, D, D> InformationType;
  
        BaseEdge() : OptimizableGraph::Edge()
        {
          _dimension = D;
        }
  
        virtual ~BaseEdge() {}
  
        virtual double chi2() const 
        {
          return _error.dot(information()*_error);
        }
  
        virtual const double* errorData() const { return _error.data();}
        virtual double* errorData() { return _error.data();}
        const ErrorVector& error() const { return _error;}
        ErrorVector& error() { return _error;}
  
        //! information matrix of the constraint
        const InformationType& information() const { return _information;}
        InformationType& information() { return _information;}
        void setInformation(const InformationType& information) { _information = information;}
  
        virtual const double* informationData() const { return _information.data();}
        virtual double* informationData() { return _information.data();}
  
        //! accessor functions for the measurement represented by the edge
        const Measurement& measurement() const { return _measurement;}
        virtual void setMeasurement(const Measurement& m) { _measurement = m;}
  
        virtual int rank() const {return _dimension;}
  
        virtual void initialEstimate(const OptimizableGraph::VertexSet&, OptimizableGraph::Vertex*)
        {
          std::cerr << "inititialEstimate() is not implemented, please give implementation in your derived class" << std::endl;
        }
  
      protected:
  
        Measurement _measurement;
        InformationType _information;
        ErrorVector _error;
  
        /**
         * calculate the robust information matrix by updating the information matrix of the error
         */
        InformationType robustInformation(const Eigen::Vector3d& rho)
        {
          InformationType result = rho[1] * _information;
          //ErrorVector weightedErrror = _information * _error;
          //result.noalias() += 2 * rho[2] * (weightedErrror * weightedErrror.transpose());
          return result;
        }
  
      public:
        EIGEN_MAKE_ALIGNED_OPERATOR_NEW
    };
  
  } // end namespace g2o
  
  #endif
  