QMCMikesBracketingStepLengthSelector.h

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//            QMcBeaver
//
//         Constructed by 
//
//     Michael Todd Feldmann 
//              and 
//   David Randall "Chip" Kent IV
//
// Copyright 2000-2.  All rights reserved.
//
// drkent@users.sourceforge.net mtfeldmann@users.sourceforge.net

#ifndef QMCMikesBracketingStepLengthSelector_H
#define QMCMikesBracketingStepLengthSelector_H

#include <iostream>

#include "IeeeMath.h"
#include "QMCLineSearchStepLengthSelectionAlgorithm.h"

using namespace std;

class QMCMikesBracketingStepLengthSelector : 
public QMCLineSearchStepLengthSelectionAlgorithm
{
public:
  double stepLength(QMCObjectiveFunction *function, 
                    Array1D<double> & position,
                    Array1D<double> & searchDirection,
                    Array1D<double> & gradient,
                    Array2D<double> & unused,
                    double functionValue);

private:
  void bracket(QMCObjectiveFunction *OF,Array1D<double> & position,
               Array1D<double> & searchDirection,
               double alpha_zero,double scale,int recursion_depth);

  void quadratic_rebracketer(QMCObjectiveFunction * OF,
                             Array1D<double> & position,
                             Array1D<double> & searchDirection);

  void print_interval();
  
  //The next six variables make up an interval to do a parabolic fit to.
  //Think of the alphas as "x" and the scores as "y" to find the best "x"
  //which will be the new alpha_middle
  double alpha_left;      
  double alpha_middle;
  double alpha_right;
  double score_left;
  double score_middle;
  double score_right;


};

#endif

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