farfield_expansion.h

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/* MLPACK 0.2
 *
 * Copyright (c) 2008, 2009 Alexander Gray,
 *                          Garry Boyer,
 *                          Ryan Riegel,
 *                          Nikolaos Vasiloglou,
 *                          Dongryeol Lee,
 *                          Chip Mappus, 
 *                          Nishant Mehta,
 *                          Hua Ouyang,
 *                          Parikshit Ram,
 *                          Long Tran,
 *                          Wee Chin Wong
 *
 * Copyright (c) 2008, 2009 Georgia Institute of Technology
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 */
#ifndef FARFIELD_EXPANSION
#define FARFIELD_EXPANSION

#include "fastlib/fastlib.h"
#include "kernel_aux.h"
#include "series_expansion_aux.h"

template<typename TKernelAux> 
class LocalExpansion;

template<typename TKernelAux>
class FarFieldExpansion {

 private:
  

  Vector center_;
  
  Vector coeffs_;

  int order_;
  
  const TKernelAux *ka_;

  const typename TKernelAux::TKernel *kernel_;

  const typename TKernelAux::TSeriesExpansionAux *sea_;

  OT_DEF(FarFieldExpansion) {
    OT_MY_OBJECT(center_);
    OT_MY_OBJECT(coeffs_);
    OT_MY_OBJECT(order_);
  }

 public:
  
  
  double bandwidth_sq() const { return kernel_->bandwidth_sq(); }

  Vector* get_center() { return &center_; }

  const Vector* get_center() const { return &center_; }

  const Vector& get_coeffs() const { return coeffs_; }
  
  int get_order() const { return order_; }
  
  int get_max_order() const { return sea_->get_max_order(); }

  double get_weight_sum() const { return coeffs_[0]; }

  void set_order(int new_order) { order_ = new_order; }
  
  void set_center(const Vector &center) {
    
    for(index_t i = 0; i < center.length(); i++) {
      center_[i] = center[i];
    }
  }

  
  void Accumulate(const Vector &reference_point, double weight, int order);

  void AccumulateCoeffs(const Matrix& data, const Vector& weights,
                        int begin, int end, int order);

  void RefineCoeffs(const Matrix& data, const Vector& weights,
                    int begin, int end, int order);
  
  double EvaluateField(const Matrix& data, int row_num, int order) const;
  double EvaluateField(const double *x_q, int order) const;

  double MixField(const Matrix &data, int node1_begin, int node1_end, 
                  int node2_begin, int node2_end, const FarFieldExpansion &fe2,
                  const FarFieldExpansion &fe3, int order2, int order3) const;

  double ConvolveField(const FarFieldExpansion &fe, int order) const;

  double ConvolveField(const FarFieldExpansion &fe2,
                       const FarFieldExpansion &fe3,
                       int order1, int order2, int order3) const;

  void Init(const Vector& center, const TKernelAux &ka);
  void Init(const TKernelAux &ka);

  template<typename TBound>
  int OrderForConvolving(const TBound &far_field_region,
                         const Vector &far_field_region_centroid,
                         const TBound &local_field_region,
                         const Vector &local_field_region_centroid,
                         double min_dist_sqd_regions,
                         double max_dist_dsqd_regons,
                         double max_error, double *actual_error) const;

  template<typename TBound>
  int OrderForEvaluating(const TBound &far_field_region,
                         const TBound &local_field_region,
                         double min_dist_sqd_regions,
                         double max_dist_sqd_regions,
                         double max_error, double *actual_error) const;

  template<typename TBound>
  int OrderForConvertingToLocal(const TBound &far_field_region,
                                const TBound &local_field_region, 
                                double min_dist_sqd_regions, 
                                double max_dist_sqd_regions,
                                double required_bound, 
                                double *actual_error) const;

  void PrintDebug(const char *name="", FILE *stream=stderr) const;

  void TranslateFromFarField(const FarFieldExpansion &se);
  
  void TranslateToLocal(LocalExpansion<TKernelAux> &se, int truncation_order);

};

#define INSIDE_FARFIELD_EXPANSION_H
#include "farfield_expansion_impl.h"
#undef INSIDE_FARFIELD_EXPANSION_H

#endif