DiagonalizedFactorsProductVariable.cc

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// -*- C++ -*-

// PLearn (A C++ Machine Learning Library)
// Copyright (C) 1998 Pascal Vincent
// Copyright (C) 1999-2002 Pascal Vincent, Yoshua Bengio, Rejean Ducharme and University of Montreal
// Copyright (C) 2001-2002 Nicolas Chapados, Ichiro Takeuchi, Jean-Sebastien Senecal
// Copyright (C) 2002 Xiangdong Wang, Christian Dorion

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// modification, are permitted provided that the following conditions are met:
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//  1. Redistributions of source code must retain the above copyright
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/* *******************************************************      
   * $Id: DiagonalizedFactorsProductVariable.cc,v 1.1 2004/07/19 22:31:11 yoshua Exp $
   * This file is part of the PLearn library.
   ******************************************************* */

#include "DiagonalizedFactorsProductVariable.h"
#include "Var_utils.h"

namespace PLearn {
using namespace std;


PLEARN_IMPLEMENT_OBJECT(DiagonalizedFactorsProductVariable,
                        "Variable that represents the leftmatrix*diag(vector)*rightmatrix product",
                        "The three parents are respectively the left matrix U, the center vector d,\n"
                        "and the right matrix V. Options allow to transpose the matrices.\n"
                        "The output value has elements (i,j) equal to sum_k U_{ik} d_k V_{kj}\n"
                        );

DiagonalizedFactorsProductVariable::DiagonalizedFactorsProductVariable(Var left_matrix, 
                                                                       Var center_diagonal, 
                                                                       Var right_matrix,
                                                                       bool transpose_left_, 
                                                                       bool transpose_right_)
    : inherited(left_matrix & center_diagonal & (VarArray)right_matrix,
                transpose_left_?left_matrix->width():left_matrix->length(), 
                transpose_right_?right_matrix->length():right_matrix->width()),
      transpose_left(transpose_left_), transpose_right(transpose_right_)
{
    build_();
}

void
DiagonalizedFactorsProductVariable::build()
{
    inherited::build();
    build_();
}

void
DiagonalizedFactorsProductVariable::build_()
{
    if (varray.size()) {
      int nl = transpose_left?leftMatrix()->length():leftMatrix()->width();
      int nr = transpose_right?rightMatrix()->width():rightMatrix()->length();
      int nc = centerDiagonal()->size();
      if (nl != nc || nr != nc)
        PLERROR("In DiagonalizedFactorsProductVariable: arguments have incompatible sizes!");
    }
}

void DiagonalizedFactorsProductVariable::recomputeSize(int& l, int& w) const
{
    if (varray.size()) {
      l = transpose_left?varray[0]->width():varray[0]->length();
      w = transpose_right?varray[2]->length():varray[2]->width();
    } else
      l = w = 0;
}

void DiagonalizedFactorsProductVariable::fprop()
{
  if (transpose_left)
    {
      if (transpose_right)
        diagonalizedFactorsTransposeProductTranspose(matValue,leftMatrix()->matValue,centerDiagonal()->value,rightMatrix()->matValue);
      else
        diagonalizedFactorsTransposeProduct(matValue,leftMatrix()->matValue,centerDiagonal()->value,rightMatrix()->matValue);
    } else {
      if (transpose_right)
        diagonalizedFactorsProductTranspose(matValue,leftMatrix()->matValue,centerDiagonal()->value,rightMatrix()->matValue);
      else
        diagonalizedFactorsProduct(matValue,leftMatrix()->matValue,centerDiagonal()->value,rightMatrix()->matValue);
    }
}


void DiagonalizedFactorsProductVariable::bprop()
{
  if (transpose_left)
  {
    if (transpose_right)
    {
      // SINCE res[i,j] = sum_k U[k,i] d[k] V[j,k] ==>
      // dC/dU[k,i] = d_k * sum_j dC/dres[i,j] V[j,k]
      // dC/dd[k] = sum_{ij} dC/dres[i,j] U[k,i] V[j,k]
      // dC/dV[j,k] = d_k * sum_i dC/dres[i,j] U[k,i]
      diagonalizedFactorsTransposeProductTransposeBprop(matGradient,leftMatrix()->matValue,
                                                        centerDiagonal()->value,rightMatrix()->matValue,
                                                        leftMatrix()->matGradient,
                                                        centerDiagonal()->gradient,rightMatrix()->matGradient); 
    }
    else
    {
      // SINCE res[i,j] = sum_k U[k,i] d[k] V[k,j] ==>
      // dC/dU[k,i] = d_k * sum_j dC/dres[i,j] V[k,j]
      // dC/dd[k] = sum_{ij} dC/dres[i,j] U[k,i] V[k,j]
      // dC/dV[k,j] = d_k sum_i dC/dres[i,j] U[k,i]
      diagonalizedFactorsTransposeProductBprop(matGradient,leftMatrix()->matValue,centerDiagonal()->value,
                                               rightMatrix()->matValue, leftMatrix()->matGradient,
                                               centerDiagonal()->gradient,rightMatrix()->matGradient); 
    }
  } 
  else 
  {
    if (transpose_right)
    {
      // SINCE res[i,j] = sum_k U[i,k] d[k] V[j,k] ==>
      // dC/dU[i,k] = sum_j dC/dres[i,j] d_k V[j,k]
      // dC/dd[k] = sum_{ij} dC/dres[i,j] U[i,k] V[j,k]
      // dC/dV[j,k] = sum_i dC/dres[i,j] d_k U[i,k]
      diagonalizedFactorsProductTransposeBprop(matGradient,leftMatrix()->matValue,centerDiagonal()->value,
                                               rightMatrix()->matValue, leftMatrix()->matGradient,
                                               centerDiagonal()->gradient,rightMatrix()->matGradient); 
    }
    else
    {    
      // SINCE res[i,j] = sum_k U[i,k] d[k] V[k,j] ==>
      // dC/dU[i,k] += sum_j dC/dres[i,j] d_k V[k,j]
      // dC/dd[k] += sum_{ij} dC/dres[i,j] U[i,k] V[k,j]
      // dC/dV[k,j] += d_k * sum_i U[i,k] dC/dres[i,j] 
      diagonalizedFactorsProductBprop(matGradient,leftMatrix()->matValue,centerDiagonal()->value,
                                      rightMatrix()->matValue,leftMatrix()->matGradient,
                                      centerDiagonal()->gradient,rightMatrix()->matGradient);
    }  
  }
}


} // end of namespace PLearn

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