GeneralGrid.h

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//////////////////////////////////////////////////////////////////////////////////////
// This file is distributed under the University of Illinois/NCSA Open Source License.
// See LICENSE file in top directory for details.
//
// Copyright (c) 2016 Jeongnim Kim and QMCPACK developers.
//
// File developed by: Paul R. C. Kent, kentpr@ornl.gov, Oak Ridge National Laboratory
//                    Mark A. Berrill, berrillma@ornl.gov, Oak Ridge National Laboratory
//
// File created by: Paul R. C. Kent, kentpr@ornl.gov, Oak Ridge National Laboratory
//////////////////////////////////////////////////////////////////////////////////////


#ifndef SIMPLE_GRID_H
#define SIMPLE_GRID_H

#include <vector>


class SimpleGrid
{
private:
  std::vector<double> grid;

public:
  inline int NumPoints() { return grid.size(); }

  inline std::vector<double>& Points() { return grid; }

  inline double operator[](int i) { return grid[i]; }

  /// Returns the index of the nearest point below r.
  int ReverseMap(double r)
  {
    int n = grid.size();
    if (r <= grid[0])
      return (0);
    else if (r >= grid[n - 1])
      return n - 1;
    else
    {
      int hi    = n - 1;
      int lo    = 0;
      bool done = false;
      while (!done)
      {
        int i = (hi + lo) >> 1;
        if (grid[i] > r)
          hi = i;
        else
          lo = i;
        done = (hi - lo) < 2;
      }
      if (grid[lo] >= r)
        lo--;
      return (lo);
    }
  }

  inline double Start() { return grid[0]; }

  inline double End() { return grid[grid.size() - 1]; }

  void Init(std::vector<double>& points)
  {
    grid.resize(points.size());
    grid = points;
  }

  /// Useless constructor
  SimpleGrid()
  { /*  Do nothing */
  }
};

#endif