NonlinearlySpaced.h

//-*-C++-*-
/***************************************************************************
 *
 *   Copyright (C) 2007 by Willem van Straten
 *   Licensed under the Academic Free License version 2.1
 *
 ***************************************************************************/
 
// psrchive/More/General/Pulsar/NonlinearlySpaced.h
 
#ifndef __Pulsar_NonlinearlySpaced_h
#define __Pulsar_NonlinearlySpaced_h
 
#include "Pulsar/Divided.h"
#include "debug.h"
 
#include <cmath>
 
namespace Pulsar {
 
  template<class C>
  class Integrate<C>::NonlinearlySpaced : public Integrate<C>::Divided
  {

    void initialize (Integrate*, C*);

    unsigned get_nrange () { return stop_indeces.size(); }
 
    void get_range (unsigned irange, unsigned& start, unsigned& stop);

    virtual double get_value (const C*, unsigned ielement) = 0;
 
  protected:

    std::vector<unsigned> stop_indeces;
 
  };
 
}
 
template<class C>
void Pulsar::Integrate<C>::NonlinearlySpaced::initialize (Integrate*, 
                                                          C* container)
{
  unsigned container_size = this->get_size( container );
 
  // divide them up
  unsigned output_elements = 0;
  unsigned spacing = 0;
  this->divide (container_size, output_elements, spacing);
 
  DEBUG("NonlinearlySpaced::initialize container_size=" << container_size << " output_elements=" << output_elements);
  
  if (output_elements == 0)
    return;
  
  stop_indeces.resize (output_elements);
  stop_indeces[output_elements-1] = container_size;
 
  if (output_elements == 1)
    return;
  
  double value_0 = get_value (container, 0);
  double value_range = get_value (container, container_size - 1) - value_0;
  double value_step = value_range / output_elements;
 
  DEBUG("NonlinearlySpaced::initialize value_0=" << value_0 << " value_range=" << value_range);
      
  unsigned ielement = 0;
  
  for (unsigned irange=0; irange+1 < output_elements; irange++)
  {
    double stop_value = value_0 + (irange+1) * value_step;
 
    DEBUG("NonlinearlySpaced::initialize stop_value[" << irange << "]=" << stop_value);
 
    bool first = true;
    double min_diff = 0;
    
    while (ielement < container_size)
    {
      double value = get_value (container, ielement);
      double diff = std::fabs( value - stop_value );
 
      DEBUG("NonlinearlySpaced::initialize value[" << ielement << "]=" << value << " diff=" << diff);
 
      if (first)
        min_diff = diff;
      else if (diff > min_diff)
        break;
      else
        min_diff = diff;
 
      ielement ++;
      first = false;
    }
 
    DEBUG("NonlinearlySpaced::initialize stop_index[" << irange << "]=" << ielement);
 
    stop_indeces[irange] = ielement;
  }
}
 
template<class C>
void Pulsar::Integrate<C>::NonlinearlySpaced::get_range (unsigned irange, 
                                                         unsigned& start, 
                                                         unsigned& stop)
{
  if (irange >= stop_indeces.size())
    throw Error (InvalidParam, 
                 "Pulsar::Integrate::Divide::NonlinearlySpaced::get_range",
                 "irange=%u >= output_elements=%u", irange, stop_indeces.size());
 
  if (irange > 0)
    start = stop_indeces[irange-1];
  else
    start = 0;
 
  stop = stop_indeces[irange];
}
 
 
 
#endif