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Lewis Van Winkle
346
genann.c
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346
genann.c
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/*
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* GENANN - Minimal C Artificial Neural Network
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*
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* Copyright (c) 2015, 2016 Lewis Van Winkle
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*
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* http://CodePlea.com
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*
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* This software is provided 'as-is', without any express or implied
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* warranty. In no event will the authors be held liable for any damages
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* arising from the use of this software.
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*
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* Permission is granted to anyone to use this software for any purpose,
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* including commercial applications, and to alter it and redistribute it
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* freely, subject to the following restrictions:
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*
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* 1. The origin of this software must not be misrepresented; you must not
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* claim that you wrote the original software. If you use this software
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* in a product, an acknowledgement in the product documentation would be
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* appreciated but is not required.
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* 2. Altered source versions must be plainly marked as such, and must not be
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* misrepresented as being the original software.
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* 3. This notice may not be removed or altered from any source distribution.
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*
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*/
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#include "genann.h"
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#include <stdlib.h>
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#include <string.h>
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#include <math.h>
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#include <assert.h>
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#include <stdio.h>
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#define LOOKUP_SIZE 4096
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double genann_act_sigmoid(double a) {
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if (a < -45.0) return 0;
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if (a > 45.0) return 1;
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return 1.0 / (1 + exp(-a));
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}
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double genann_act_sigmoid_cached(double a) {
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/* If you're optimizing for memory usage, just
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* delete this entire function and replace references
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* of genann_act_sigmoid_cached to genann_act_sigmoid
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*/
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const double min = -15.0;
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const double max = 15.0;
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static double interval;
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static int initialized = 0;
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static double lookup[LOOKUP_SIZE];
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/* Calculate entire lookup table on first run. */
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if (!initialized) {
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interval = (max - min) / LOOKUP_SIZE;
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int i;
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for (i = 0; i < LOOKUP_SIZE; ++i) {
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lookup[i] = genann_act_sigmoid(min + interval * i);
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}
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/* This is down here to make this thread safe. */
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initialized = 1;
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}
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int i;
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i = (int)((a-min)/interval+0.5);
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if (i <= 0) return lookup[0];
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if (i >= LOOKUP_SIZE) return lookup[LOOKUP_SIZE-1];
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return lookup[i];
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}
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double genann_act_threshold(double a) {
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return a > 0;
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}
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GENANN *genann_init(int inputs, int hidden_layers, int hidden, int outputs) {
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if (hidden_layers < 0) return 0;
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if (inputs < 1) return 0;
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if (outputs < 1) return 0;
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if (hidden_layers > 0 && hidden < 1) return 0;
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const int hidden_weights = hidden_layers ? (inputs+1) * hidden + (hidden_layers-1) * (hidden+1) * hidden : 0;
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const int output_weights = (hidden_layers ? (hidden+1) : (inputs+1)) * outputs;
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const int total_weights = (hidden_weights + output_weights);
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const int total_neurons = (inputs + hidden * hidden_layers + outputs);
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/* Allocate extra size for weights, outputs, and deltas. */
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const int size = sizeof(GENANN) + sizeof(double) * (total_weights + total_neurons + (total_neurons - inputs));
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GENANN *ret = malloc(size);
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if (!ret) return 0;
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ret->inputs = inputs;
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ret->hidden_layers = hidden_layers;
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ret->hidden = hidden;
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ret->outputs = outputs;
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ret->total_weights = total_weights;
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ret->total_neurons = total_neurons;
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/* Set pointers. */
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ret->weight = (double*)((char*)ret + sizeof(GENANN));
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ret->output = ret->weight + ret->total_weights;
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ret->delta = ret->output + ret->total_neurons;
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genann_randomize(ret);
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ret->activation_hidden = genann_act_sigmoid_cached;
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ret->activation_output = genann_act_sigmoid_cached;
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return ret;
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}
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GENANN *genann_read(FILE *in) {
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int inputs, hidden_layers, hidden, outputs;
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fscanf(in, "%d %d %d %d", &inputs, &hidden_layers, &hidden, &outputs);
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GENANN *ann = genann_init(inputs, hidden_layers, hidden, outputs);
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int i;
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for (i = 0; i < ann->total_weights; ++i) {
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fscanf(in, " %le", ann->weight + i);
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}
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return ann;
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}
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GENANN *genann_copy(GENANN const *ann) {
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const int size = sizeof(GENANN) + sizeof(double) * (ann->total_weights + ann->total_neurons + (ann->total_neurons - ann->inputs));
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GENANN *ret = malloc(size);
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if (!ret) return 0;
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memcpy(ret, ann, size);
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/* Set pointers. */
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ret->weight = (double*)((char*)ret + sizeof(GENANN));
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ret->output = ret->weight + ret->total_weights;
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ret->delta = ret->output + ret->total_neurons;
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return ret;
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}
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void genann_randomize(GENANN *ann) {
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int i;
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for (i = 0; i < ann->total_weights; ++i) {
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double r = GENANN_RANDOM();
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/* Sets weights from -0.5 to 0.5. */
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ann->weight[i] = r - 0.5;
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}
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}
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void genann_free(GENANN *ann) {
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/* The weight, output, and delta pointers go to the same buffer. */
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free(ann);
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}
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double const *genann_run(GENANN const *ann, double const *inputs) {
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double const *w = ann->weight;
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double *o = ann->output + ann->inputs;
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double const *i = ann->output;
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/* Copy the inputs to the scratch area, where we also store each neuron's
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* output, for consistency. This way the first layer isn't a special case. */
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memcpy(ann->output, inputs, sizeof(double) * ann->inputs);
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int h, j, k;
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const GENANN_ACTFUN act = ann->activation_hidden;
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const GENANN_ACTFUN acto = ann->activation_output;
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/* Figure hidden layers, if any. */
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for (h = 0; h < ann->hidden_layers; ++h) {
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for (j = 0; j < ann->hidden; ++j) {
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double sum = 0;
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for (k = 0; k < (h == 0 ? ann->inputs : ann->hidden) + 1; ++k) {
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if (k == 0) {
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sum += *w++ * -1.0;
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} else {
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sum += *w++ * i[k-1];
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}
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}
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*o++ = act(sum);
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}
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i += (h == 0 ? ann->inputs : ann->hidden);
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}
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double const *ret = o;
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/* Figure output layer. */
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for (j = 0; j < ann->outputs; ++j) {
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double sum = 0;
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for (k = 0; k < (ann->hidden_layers ? ann->hidden : ann->inputs) + 1; ++k) {
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if (k == 0) {
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sum += *w++ * -1.0;
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} else {
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sum += *w++ * i[k-1];
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}
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}
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*o++ = acto(sum);
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}
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/* Sanity check that we used all weights and wrote all outputs. */
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assert(w - ann->weight == ann->total_weights);
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assert(o - ann->output == ann->total_neurons);
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return ret;
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}
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void genann_train(GENANN const *ann, double const *inputs, double const *desired_outputs, double learning_rate) {
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/* To begin with, we must run the network forward. */
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genann_run(ann, inputs);
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int h, j, k;
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/* First set the output layer deltas. */
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{
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double const *o = ann->output + ann->inputs + ann->hidden * ann->hidden_layers; /* First output. */
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double *d = ann->delta + ann->hidden * ann->hidden_layers; /* First delta. */
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double const *t = desired_outputs; /* First desired output. */
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/* Set output layer deltas. */
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for (j = 0; j < ann->outputs; ++j) {
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*d = (*t - *o) * *o * (1.0 - *o);
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++o; ++d; ++t;
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}
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}
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/* Set hidden layer deltas, start on last layer and work backwards. */
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/* Note that loop is skipped in the case of hidden_layers == 0. */
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for (h = ann->hidden_layers - 1; h >= 0; --h) {
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/* Find first output and delta in this layer. */
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double const *o = ann->output + ann->inputs + (h * ann->hidden);
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double *d = ann->delta + (h * ann->hidden);
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/* Find first delta in following layer (which may be hidden or output). */
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double const * const dd = ann->delta + ((h+1) * ann->hidden);
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/* Find first weight in following layer (which may be hidden or output). */
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double const * const ww = ann->weight + ((ann->inputs+1) * ann->hidden) + ((ann->hidden+1) * ann->hidden * (h));
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for (j = 0; j < ann->hidden; ++j) {
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double delta = 0;
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for (k = 0; k < (h == ann->hidden_layers-1 ? ann->outputs : ann->hidden); ++k) {
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const double forward_delta = dd[k];
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const int windex = k * (ann->hidden + 1) + (j + 1);
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const double forward_weight = ww[windex];
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delta += forward_delta * forward_weight;
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}
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*d = *o * (1.0-*o) * delta;
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++d; ++o;
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}
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}
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/* Train the outputs. */
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{
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/* Find first output delta. */
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double const *d = ann->delta + ann->hidden * ann->hidden_layers; /* First output delta. */
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/* Find first weight to first output delta. */
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double *w = ann->weight + (ann->hidden_layers
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? ((ann->inputs+1) * ann->hidden + (ann->hidden+1) * ann->hidden * (ann->hidden_layers-1))
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: (0));
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/* Find first output in previous layer. */
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double const * const i = ann->output + (ann->hidden_layers
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? (ann->inputs + (ann->hidden) * (ann->hidden_layers-1))
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: 0);
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/* Set output layer deltas. */
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for (j = 0; j < ann->outputs; ++j) {
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for (k = 0; k < (ann->hidden_layers ? ann->hidden : ann->inputs) + 1; ++k) {
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if (k == 0) {
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*w++ += *d * learning_rate * -1.0;
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} else {
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*w++ += *d * learning_rate * i[k-1];
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}
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}
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++d;
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}
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assert(w - ann->weight == ann->total_weights);
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}
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/* Train the hidden layers. */
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for (h = ann->hidden_layers - 1; h >= 0; --h) {
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/* Find first delta in this layer. */
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double const *d = ann->delta + (h * ann->hidden);
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/* Find first input to this layer. */
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double const *i = ann->output + (h
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? (ann->inputs + ann->hidden * (h-1))
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: 0);
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/* Find first weight to this layer. */
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double *w = ann->weight + (h
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? ((ann->inputs+1) * ann->hidden + (ann->hidden+1) * (ann->hidden) * (h-1))
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: 0);
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for (j = 0; j < ann->hidden; ++j) {
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for (k = 0; k < (h == 0 ? ann->inputs : ann->hidden) + 1; ++k) {
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if (k == 0) {
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*w++ += *d * learning_rate * -1.0;
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} else {
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*w++ += *d * learning_rate * i[k-1];
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}
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}
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++d;
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}
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}
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}
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void genann_write(GENANN const *ann, FILE *out) {
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fprintf(out, "%d %d %d %d", ann->inputs, ann->hidden_layers, ann->hidden, ann->outputs);
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int i;
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for (i = 0; i < ann->total_weights; ++i) {
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fprintf(out, " %.20e", ann->weight[i]);
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}
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}
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