diff --git a/.gitignore b/.gitignore
index cd531cf..13f78e0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -52,3 +52,4 @@ Module.symvers
 Mkfile.old
 dkms.conf
 
+csv/
diff --git a/headers/file.h b/headers/file.h
new file mode 100644
index 0000000..bd3f747
--- /dev/null
+++ b/headers/file.h
@@ -0,0 +1,17 @@
+/* See LICENSE file for copyright and license details. */
+
+#ifndef _file_h_
+#define _file_h_
+
+typedef struct {
+	FILE *file;
+	char *file_name;
+} File;
+
+File *new_file(char *file_name);
+void free_file(File *f);
+double get_entry(File *f, int row, int col, char sep);
+int get_columns_num(File *f, int row, char sep);
+int get_rows_num(File *f);
+
+#endif
diff --git a/headers/layer.h b/headers/layer.h
new file mode 100644
index 0000000..583f47c
--- /dev/null
+++ b/headers/layer.h
@@ -0,0 +1,17 @@
+/* See LICENSE file for copyright and license details. */
+
+#ifndef _layer_h_
+#define _layer_h_
+
+#include "../headers/perceptron.h"
+
+typedef struct {
+	int p_num;
+	Perceptron **p;
+} Layer;
+
+Layer *new_layer(int p_num, int i_num);
+Layer *new_input_layer(int p_num);
+void free_layer(Layer *l);
+
+#endif
diff --git a/headers/neural_net.h b/headers/neural_net.h
new file mode 100644
index 0000000..39ae484
--- /dev/null
+++ b/headers/neural_net.h
@@ -0,0 +1,16 @@
+/* See LICENSE file for copyright and license details. */
+
+#ifndef _neural_net_h_
+#define _neural_net_h_
+
+#include "layer.h"
+
+typedef struct {
+	int l_num;
+	Layer **l;
+} NeuralNet;
+
+NeuralNet *new_neural_net(char *c_file_name, char *i_file_name);
+void free_neural_net(NeuralNet *n);
+
+#endif
diff --git a/headers/perceptron.h b/headers/perceptron.h
new file mode 100644
index 0000000..e655704
--- /dev/null
+++ b/headers/perceptron.h
@@ -0,0 +1,15 @@
+/* See LICENSE file for copyright and license details. */
+
+#ifndef _perceptron_h_
+#define _perceptron_h_
+
+typedef struct {
+	int i_num;
+	double *weights;
+	double output;
+} Perceptron;
+
+Perceptron *new_perceptron(int i_num);
+void free_perceptron(Perceptron *p);
+
+#endif
diff --git a/headers/training.h b/headers/training.h
new file mode 100644
index 0000000..f80f988
--- /dev/null
+++ b/headers/training.h
@@ -0,0 +1,9 @@
+/* See LICENSE file for copyright and license details. */
+
+#ifndef _training_h_
+#define _training_h_
+
+void train_by_backpropagation(NeuralNet *n, int runs, double t_factor,
+		char *i_name, char *t_name);
+
+#endif
diff --git a/src/file.c b/src/file.c
new file mode 100644
index 0000000..b498128
--- /dev/null
+++ b/src/file.c
@@ -0,0 +1,99 @@
+/* See LICENSE file for copyright and license details. */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "../headers/file.h"
+
+#define BUF_SIZE 1024
+
+File
+*new_file(char *file_name)
+{
+	File *f;
+	
+	if ((f = malloc(sizeof(File))) == NULL) {
+		fprintf(stderr, "memory for file was not allocated.\n");
+		exit(EXIT_FAILURE);
+	}
+
+	f->file_name = file_name;
+	//fprintf(stderr, "%s\n", f->file_name);
+
+	if ((f->file = fopen(f->file_name, "r")) == NULL) {
+		fprintf(stderr, "file %s was not opened.\n",
+				f->file_name);
+		exit(EXIT_FAILURE);
+	}
+
+	return f;
+}
+
+void
+free_file(File *f)
+{
+	if (fclose(f->file) == EOF) {
+		fprintf(stderr, "file %s was not closed.\n",
+				f->file_name);
+		exit(EXIT_FAILURE);
+	}
+	free(f);
+}
+
+double
+get_entry(File *f, int row, int col, char sep)
+{
+	int i;
+	char buf[BUF_SIZE];
+	double x;
+
+	rewind(f->file);
+
+	for (i=0; i<row; i++)
+		fgets(buf, BUF_SIZE, f->file);
+
+	for (i=0; i<col; i++) {
+		while (fgetc(f->file) != sep)
+			;
+	}
+
+	fscanf(f->file, "%lf", &x);
+	return x;
+}
+
+int
+get_columns_num(File *f, int row, char sep)
+{
+	int i, count;
+	char c, buf[BUF_SIZE];
+
+	c = '0';
+	count = 1;
+	rewind(f->file);
+
+	for (i=0; i<row; i++)
+		fgets(buf, BUF_SIZE, f->file);
+
+	while (c != '\n') {
+		c = fgetc(f->file);
+		if (c == sep)
+			count++;
+	}
+
+	return count;
+}
+
+int
+get_rows_num(File *f)
+{
+	char buf[BUF_SIZE];
+	int count;
+
+	count = 0;
+	rewind(f->file);
+
+	while (fgets(buf, BUF_SIZE, f->file))
+		count++;
+
+	return count;
+}
diff --git a/src/layer.c b/src/layer.c
new file mode 100644
index 0000000..486d6c6
--- /dev/null
+++ b/src/layer.c
@@ -0,0 +1,66 @@
+/* See LICENSE file for copyright and license details. */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "../headers/layer.h"
+
+Layer
+*new_layer(int p_num, int i_num)
+{
+	int i;
+	Layer *l;
+
+	l = malloc(sizeof(Layer));
+
+	l->p_num = p_num;
+
+	l->p = calloc(l->p_num, sizeof(Perceptron *));
+
+	for (i=0; i<l->p_num; i++) {
+		l->p[i] = new_perceptron(i_num);
+	}
+	
+	if (l==NULL || l->p==NULL) {
+		fprintf(stderr, "memory for layer was not allocated.\n");
+		exit(EXIT_FAILURE);
+	}
+
+	return l;
+}
+
+Layer
+*new_input_layer(int p_num)
+{
+	int i;
+	Layer *l;
+
+	l = malloc(sizeof(Layer));
+
+	l->p_num = p_num;
+
+	l->p = calloc(l->p_num, sizeof(Perceptron *));
+
+	for (i=0; i<l->p_num; i++) {
+		l->p[i] = new_perceptron(1);
+	}
+
+	if (l==NULL || l->p==NULL) {
+		fprintf(stderr, "memory for layer was not allocated.\n");
+		exit(EXIT_FAILURE);
+	}
+
+	return l;
+}
+
+void
+free_layer(Layer *l)
+{
+	int i;
+
+	for (i=0; i<l->p_num; i++) {
+		free_perceptron(l->p[i]);
+	}
+	free(l->p);
+	free(l);
+}
diff --git a/src/main.c b/src/main.c
new file mode 100644
index 0000000..025a2d7
--- /dev/null
+++ b/src/main.c
@@ -0,0 +1,22 @@
+/* See LICENSE file for copyright and license details. */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "../headers/file.h"
+#include "../headers/neural_net.h"
+#include "../headers/training.h"
+
+#define N 100000
+
+int
+main(int argc, char *argv[])
+{
+	NeuralNet *n = new_neural_net(argv[1], argv[2]);
+
+	train_by_backpropagation(n, N, 1, argv[2], argv[3]);
+
+	free_neural_net(n);
+
+	return EXIT_SUCCESS;
+}
diff --git a/src/neural_net.c b/src/neural_net.c
new file mode 100644
index 0000000..55691a7
--- /dev/null
+++ b/src/neural_net.c
@@ -0,0 +1,59 @@
+/* See LICENSE file for copyright and license details. */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "../headers/file.h"
+#include "../headers/neural_net.h"
+
+NeuralNet
+*new_neural_net(char *c_file_name, char *i_file_name)
+{
+	int i;
+	NeuralNet *n;
+	File *c_file = new_file(c_file_name);
+	File *i_file = new_file(i_file_name);
+
+	n = malloc(sizeof(NeuralNet));
+	n->l_num = get_columns_num(c_file, 0, ',');
+	n->l     = calloc(n->l_num, sizeof(Layer *));
+	int p_num[n->l_num];
+	int i_num[n->l_num];
+
+	for (i=0; i<n->l_num-1; i++) {
+		p_num[i] = get_entry(c_file, 0, i, ',') + 1;
+	}
+	p_num[n->l_num-1] = get_entry(c_file, 0, n->l_num-1, ',');
+
+	i_num[0] = get_columns_num(i_file, 0, ',');
+	for (i=1; i<n->l_num; i++) {
+		i_num[i] = p_num[i-1];
+	}
+
+	free_file(c_file);
+	free_file(i_file);
+
+	n->l[0] = new_input_layer(p_num[0]);
+	for (i=1; i<n->l_num; i++) {
+		n->l[i] = new_layer(p_num[i], i_num[i]);
+	}
+
+	if (n==NULL || n->l==NULL) {
+		fprintf(stderr, "memory for neural net was not allocated.\n");
+		exit(EXIT_FAILURE);
+	}
+
+	return n;
+}
+
+void
+free_neural_net(NeuralNet *n)
+{
+	int i;
+
+	for (i=0; i<n->l_num; i++) {
+		free_layer(n->l[i]);
+	}
+	free(n->l);
+	free(n);
+}
diff --git a/src/perceptron.c b/src/perceptron.c
new file mode 100644
index 0000000..dab850f
--- /dev/null
+++ b/src/perceptron.c
@@ -0,0 +1,30 @@
+/* See LICENSE file for copyright and license details. */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "../headers/perceptron.h"
+
+Perceptron
+*new_perceptron(int i_num)
+{
+	Perceptron *p;
+
+	p          = malloc(sizeof(Perceptron));
+	p->i_num   = i_num;
+	p->weights = calloc(i_num, sizeof(double));
+
+	if (p==NULL || p->weights==NULL) {
+		fprintf(stderr, "memory for perceptron was not allocated.\n");
+		exit(EXIT_FAILURE);
+	}
+
+	return p;
+}
+
+void
+free_perceptron(Perceptron *p)
+{
+	free(p->weights);
+	free(p);
+}
diff --git a/src/training.c b/src/training.c
new file mode 100644
index 0000000..3ec0780
--- /dev/null
+++ b/src/training.c
@@ -0,0 +1,277 @@
+/* See LICENSE file for copyright and license details. */
+
+#include <math.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+#include "../headers/file.h"
+#include "../headers/neural_net.h"
+
+typedef struct {
+	File *i_file;
+	File *t_file;
+	double t_factor;
+	int rows_num;
+	double *output_deltas;
+	double **small_deltas;
+	double ***weight_deltas;
+} TrainingInfo;
+
+static TrainingInfo *new_training_info(NeuralNet *n, char *i_name,
+		char *t_name, double t_factor);
+static void free_training_info(NeuralNet *n, TrainingInfo *t);
+static void init_inputs(NeuralNet *n);
+static void init_weights(NeuralNet *n);
+static void set_input_layer(NeuralNet *n, TrainingInfo *t, int i_file_row);
+static void calculate_outputs(NeuralNet *n);
+static void calculate_output_deltas(NeuralNet *n, TrainingInfo *t, int row);
+static void calculate_small_deltas(NeuralNet *n, TrainingInfo *t);
+static void calculate_weight_deltas(NeuralNet *n, TrainingInfo *t);
+static void calculate_weights(NeuralNet *n, TrainingInfo *t);
+static void print_weights(NeuralNet *n);
+
+void
+train_by_backpropagation(NeuralNet *n, int runs, double t_factor, char *i_name,
+		char *t_name)
+{
+	int i, j;
+	TrainingInfo *t;
+
+	t = new_training_info(n, i_name, t_name, t_factor);
+	init_inputs(n);
+	init_weights(n);
+
+	for (i=0; i<runs; i++) {
+		for (j=0; j<t->rows_num; j++) {
+			set_input_layer(n, t, j);
+			calculate_outputs(n);
+			calculate_output_deltas(n, t, j);
+			calculate_small_deltas(n, t);
+			calculate_weight_deltas(n, t);
+			calculate_weights(n, t);
+		}
+	}
+	print_weights(n);
+
+	free_training_info(n, t);
+}
+
+static TrainingInfo
+*new_training_info(NeuralNet *n, char *i_name, char *t_name, double t_factor)
+{
+	int i, j;
+	TrainingInfo *t;
+
+	t = malloc(sizeof(TrainingInfo));
+	t->i_file = new_file(i_name);
+	t->t_file = new_file(t_name);
+	t->t_factor = t_factor;
+	t->rows_num = get_rows_num(t->i_file);
+	t->output_deltas = calloc(n->l[n->l_num-1]->p_num, sizeof(double));
+	t->small_deltas  = calloc(n->l_num-1, sizeof(double *));
+	for (i=0; i<n->l_num; i++) {
+		t->small_deltas[i]  = calloc(n->l[i]->p_num, sizeof(double));
+	}
+	t->weight_deltas = calloc(n->l_num-1, sizeof(double **));
+	for (i=1; i<n->l_num; i++) {
+		t->weight_deltas[i] = calloc(n->l[i]->p_num, sizeof(double *));
+		for (j=0; j<n->l[i]->p_num; j++) {
+			t->weight_deltas[i][j] = calloc(n->l[i-1]->p_num,
+				sizeof(double));
+		}
+	}
+
+	return t;
+}
+
+static void
+free_training_info(NeuralNet *n, TrainingInfo *t)
+{
+	int i, j;
+
+	free_file(t->i_file);
+	free_file(t->t_file);
+
+	free(t->output_deltas);
+	for (i=1; i<n->l_num; i++) {
+		free(t->small_deltas[i]);
+	}
+	free(t->small_deltas);
+	for (i=1; i<n->l_num; i++) {
+		for (j=0; j<n->l[i]->p_num; j++) {
+			free(t->weight_deltas[i][j]);
+		}
+		free(t->weight_deltas[i]);
+	}
+	free(t->weight_deltas);
+	free(t);
+}
+
+static void
+init_inputs(NeuralNet *n)
+{
+	int i;
+
+	for (i=0; i<n->l_num-1; i++) {
+		n->l[i]->p[0]->output = 1;
+	}
+}
+
+static void
+init_weights(NeuralNet *n)
+{
+	int i, j, k;
+
+	srand(time(NULL));
+	for (i=1; i<n->l_num; i++) {
+		for (j=1; j<n->l[i]->p_num; j++) {
+			for (k=0; k<n->l[i]->p[j]->i_num; k++) {
+				n->l[i]->p[j]->weights[k] = (double) rand()
+					/ RAND_MAX;
+			}
+		}
+	}
+}
+
+static void
+set_input_layer(NeuralNet *n, TrainingInfo *t, int i_file_row)
+{
+	int i;
+
+	for (i=1; i<n->l[0]->p_num-1; i++) {
+		n->l[0]->p[i]->output =
+			get_entry(t->i_file, i_file_row, i, ',');
+	}
+}
+
+static void
+calculate_outputs(NeuralNet *n)
+{
+	int i, j, k;
+	int x;
+
+	for (i=1; i<n->l_num; i++) {
+		for (j=1; j<n->l[i]->p_num; j++) {
+			x = 0;
+			for (k=0; k<n->l[i]->p[j]->i_num; k++) {
+				x -= n->l[i]->p[j]->weights[k] *
+					n->l[i-1]->p[k]->output;
+			}
+			n->l[i]->p[j]->output = 1 / (1 + exp(x));
+		}
+	}
+}
+
+static void
+calculate_output_deltas(NeuralNet *n, TrainingInfo *t, int row)
+{
+	int i;
+
+	for (i=0; i<n->l[n->l_num-1]->p_num; i++) {
+		t->output_deltas[i] = get_entry(t->t_file, row, i, ',')
+			- n->l[n->l_num-1]->p[i]->output;
+	}
+}
+
+static void
+calculate_small_deltas(NeuralNet *n, TrainingInfo *t)
+{
+	int i, j, k;
+	double sum;
+
+	for (i=0; i<n->l[n->l_num-1]->p_num; i++) {
+		t->small_deltas[n->l_num-1][i] = t->output_deltas[i]
+			* (1 - n->l[n->l_num-1]->p[i]->output)
+			* n->l[n->l_num-1]->p[i]->output;
+	}
+	
+	sum = 0;
+	for (i=0; i<n->l[n->l_num-2]->p_num; i++) {
+		sum += t->small_deltas[n->l_num-1][i];
+	}
+	for (i=1; i<n->l[n->l_num-2]->p_num; i++) {
+		for (j=0; j<n->l[n->l_num-1]->p_num; j++) {
+			t->small_deltas[n->l_num-2][i-1]
+				= (1 - n->l[n->l_num-2]->p[j]->output)
+				* n->l[n->l_num-2]->p[j]->output
+				* sum
+				* n->l[n->l_num-1]->p[j]->weights[i];
+		}
+	}
+
+	for (i=n->l_num-3; i>0; i--) {
+		sum = 0;
+		for (j=1; j<n->l[i+1]->p_num; j++) {
+			sum += t->small_deltas[i+1][j-1];
+		}
+		for (j=0; j<n->l[i]->p_num; j++) {
+			for (k=1; k<n->l[i+1]->p_num; k++) {
+				t->small_deltas[i][j]
+					= (1 - n->l[i]->p[k]->output)
+					* n->l[i]->p[k]->output
+					* sum
+					* n->l[i+1]->p[k]->weights[j];
+			}
+		}
+	}
+}
+
+static void
+calculate_weight_deltas(NeuralNet *n, TrainingInfo *t)
+{
+	int i, j, k;
+
+	for (i=n->l_num-1; i>0; i--) {
+		for (j=0; j<n->l[i]->p_num; j++) {
+			for (k=0; k<n->l[i-1]->p_num; k++) {
+				t->weight_deltas[i][j][k] = t->t_factor
+					* t->small_deltas[i][j]
+					* n->l[i-1]->p[k]->output;
+			}
+		}
+	}
+}
+
+static void
+calculate_weights(NeuralNet *n, TrainingInfo *t)
+{
+	int i, j, k;
+
+	for (i=n->l_num-1; i>0; i--) {
+		for (j=0; j<n->l[i]->p_num; j++) {
+			for (k=0; k<n->l[i-1]->p_num; k++) {
+				n->l[i]->p[j]->weights[k]
+					= n->l[i]->p[j]->weights[k]
+					- t->weight_deltas[i][j][k];
+			}
+		}
+	}
+}
+
+static void
+print_weights(NeuralNet *n)
+{
+	int i, j, k;
+
+	for (i=1; i<n->l_num-1; i++) {
+		fprintf(stderr, "L %d", i);
+		for (j=1; j<n->l[i]->p_num; j++) {
+			fprintf(stderr, "\tP %d\n", j);
+			for (k=0; k<n->l[i-1]->p_num; k++) {
+				printf("%lf,", n->l[i]->p[j]->weights[k]);
+			}
+			printf("\n");
+		}
+		printf("\n");
+	}
+	fprintf(stderr, "L %d", i);
+	for (i=0; i<n->l[n->l_num-1]->p_num; i++) {
+		fprintf(stderr, "\tP %d\n", i);
+		for (j=0; j<n->l[n->l_num-2]->p_num; j++) {
+			printf("%lf,", n->l[n->l_num-1]->p[i]->weights[j]);
+		}
+		printf("\n");
+	}
+	printf("\n");
+}