backward_pass.c

来自「C-package of "Long Short-Term Memory" fo」· C语言 代码 · 共 128 行

/*
 * $Id: backward_pass.c 1269 2007-05-09 07:49:08Z mhe $
 */
 
#include <stdio.h>
#include "lstm.h"
#include "backward_pass.h"

void backward_pass() {
    int k,i,j,u,v;
    register double sum;
    static double tmp;
    
    /* output units */
    for (k=cell_mod,j=0;k<ges_mod;k++,j++) {
        e[k] = error[j] * (1.0 - Yk_new[k]) * Yk_new[k]; // log
        /* weight update contribution */
        
        tmp = alpha * e[k];
           
        i=in_mod_b+1;
        
        for (u=0;u<num_blocks;u++) {
            i++;
            for (v=0;v<block_size[u];v++) {
                i++;
                DW[k][i] += tmp*Yk_new[i];
            }
            i++;
        }
        
        /* bias to output unit */
        DW[k][in_mod_b] += tmp;
        
    }
    
    /* error to memory cells ec[][] and internal states es[][] */

    i=in_mod_b+1;
    
    /* input gates */
    for (u=0;u<num_blocks;u++) {
        i++;
        for (v=0;v<block_size[u];v++) {
            i++;
            sum = 0;
            for (k=cell_mod;k<ges_mod;k++) {
                sum+= W[k][i]*e[k];
            }
            ec[u][v] = sum;
            es[u][v] = 0.5 * Y_out[u] * (1.0 + H[u][v]) * (1.0 - H[u][v]) * sum;
        }
        i++;
    }

    /* output gates */
    for (u=0;u<num_blocks;u++) {
        sum=0;
        for (v=0;v<block_size[u];v++) {
            sum+= H[u][v]*ec[u][v];
        }
        eo[u]=sum*(1.0-Y_out[u])*Y_out[u];
    }

    /* Derivatives of the internal state */

    derivatives();


    /* updates for weights to input and output gates and memory cells */
    i = in_mod_b + 1;
    for (u=0;u<num_blocks;u++) {        
        
        /* input gate */
        /* input */
        /*
        for (j=0;j<in_mod_b;j++) {
            sum = 0;
            for (v=0;v<block_size[u];v++) {
                sum += es[u][v]*SI[u][v][j];  
            }
            DW[i][j] += sum;
        }
        */
        /* lstm */
        for (j=in_mod_b;j<cell_mod;j++) {
            sum = 0;
            for (v=0;v<block_size[u];v++) {
                sum += es[u][v]*SI[u][v][j];  
            }
            DW[i][j] += alpha * sum;
        }
        
        /*output gate */
        i++;
        tmp = alpha * eo[u];
        
        /* input */
        /*
        for (j=0;j<in_mod;j++) {
            DW[i][j] += tmp * Yk_old[j];
        }
        */
        /* lstm */
        for (j=in_mod_b;j<cell_mod;j++) {
            DW[i][j] += tmp * Yk_old[j];
        }
        
        /* memory states */
        for (v=0;v<block_size[u];v++) {
            i++;
            tmp = alpha * es[u][v];
            /* input */
            for (j=0;j<=in_mod_b;j++) {
                DW[i][j] += tmp*SC[u][v][j];
            }
            /* lstm & bias */
            /*
            for (j=in_mod_b;j<cell_mod;j++) {
                DW[i][j] += tmp*SC[u][v][j];           
            }
            */
        }
        i++;
    }

 }