/*
 PLSI: Probabilistic Latent Semantic Indexing Tool

 $Id: plsi.h,v 1.8 2003/03/27 08:23:57 taku-ku Exp $;

 Copyright (C) 2002 Taku Kudo  All rights reserved.
 This is free software with ABSOLUTELY NO WARRANTY.

 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., 59 Temple Place - Suite 330, Boston, MA
 02111-1307, USA
*/

#ifndef PLSI_PLSI_H
#define PLSI_PLSI_H

#include <string>
#include <math.h>
#include "matrix.h"
#include "config.h"

namespace PLSI
{
  class PLSI 
  {
  private:
    unsigned int D; // size of Documents
    unsigned int W; // size of terms 
    unsigned int Z; // size of latent class
    double       R; // sum of all weight 
    double **new_pwz;
    double **new_pdz;
    double *new_pz;
    double **old_pwz;
    double **old_pdz;
    double *old_pz;
    double beta;
    Matrix matrix;

    double pzdw_norm (unsigned int id, unsigned int iw)
    {
       double sum = 0.0;
       for (unsigned int jz = 0; jz < Z; ++jz)
	 sum += (old_pz[jz] * pow(old_pdz[id][jz] * old_pwz[iw][jz], beta));
       return sum;
    }

    double pzdw  (unsigned int iz, unsigned int id, unsigned int iw, double sum)
    {
      return sum == 0 ? 0.0 : old_pz[iz] * pow(old_pdz[id][iz] * old_pwz[iw][iz], beta)/sum;
    }

    double pdw (unsigned int id, unsigned int iw) 
    {
      double sum = 0.0;
      for (unsigned int iz = 0; iz < Z; ++iz)
	sum += (old_pz[iz] * old_pdz[id][iz] * old_pwz[iw][iz]);
      return sum;
    }

    double gain ();
    double init (const char *filename = 0);

  public:
    bool learn (unsigned int, double, double, unsigned int, const char*);
    void clear ();
    bool write (const char *, unsigned int);
    bool read  (const char *);

    PLSI (): D(0), W(0), Z(0), R(0.0),
	     new_pwz(0), new_pdz(0), new_pz(0),
	     old_pwz(0), old_pdz(0), old_pz(0), beta(0.0) {};
    ~PLSI () { clear (); }
  };
}

#endif