QuadraticInterpolator.h

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#ifndef GCP_UTIL_QUADRATICINTERPOLATOR_H
#define GCP_UTIL_QUADRATICINTERPOLATOR_H

#include <pthread.h>
#include <iostream>

#define QP_ANGLE_FN(fn)  double (fn)(double angle)

namespace gcp {
  namespace util {
    
    class QuadraticInterpolator {
      
    public:
      
      static const double pi_;
      static const double twopi_;
      
      enum QuadType {
    
    QP_NORMAL,
    
    QP_SIGNED_ANGLE,
    
    QP_POSITIVE_ANGLE
      };
      
      //------------------------------------------------------------
      // Public methods
      //------------------------------------------------------------
      
      virtual ~QuadraticInterpolator();
      
      void empty();
      
      void extend(double x, double y);
      
      double evaluate(double x);
      
      double gradient(double x);
      
      void lock();
      
      void unlock();
      
      bool tryLock();
      
      bool canBracket(double x);
      
      unsigned getNpt();
      
      double getXmin();
      
      double getXmax();
      
    protected:
      
      QuadType type_;
      
      QuadraticInterpolator();
      
      void setEmptyValue(double emptyValue);
      
      friend std::ostream& gcp::util::operator<<(std::ostream& os, QuadraticInterpolator& quad);

    private:
      
      //------------------------------------------------------------
      // Resources for locking this container
      //------------------------------------------------------------
      
      bool mutexIsReady_;
      
      pthread_mutex_t mutex_;
      
      //------------------------------------------------------------
      // Structs used by this class.
      //------------------------------------------------------------
      
      struct QuadSample {
    double x;
    double y;
      };
      
      struct QuadData {
    
    int npt;          
    
    QuadSample s[3]; 
    
    void init();
      };
      
      //------------------------------------------------------------
      // Private data members
      //------------------------------------------------------------
      
      double emptyValue_;      // The value to use when npt==0 
      double x0_;              // A value which will be subtracted off
      // of the x-value to maintain accuracy
      double a_,b_,c_;         // The coefficients of the quadratic
      // equation that interpolates x[],y[]
      QuadSample s_[3];        // The samples to interpolate between 
      int npt_;                // The number of values in x[] and y[]
      
      //------------------------------------------------------------
      // Private methods
      //------------------------------------------------------------
      
      virtual double fixAngle(double angle); 
      
      void get(QuadData* data);
      
      void set(QuadData* data);
      
      double extendAngle(double a, double b);
      
    }; // End class QuadraticInterpolator
    
  } // End namespace util
} // End namespace gcp  


#endif