diff --git a/Makefile b/Makefile
index 82c0aaf..df79039 100644
--- a/Makefile
+++ b/Makefile
@@ -1,3 +1,16 @@
+default : myprogram
+
+all : myprogram
+
+clean :
+	rm *.o myprogram
+
+myprogram : main.o activations.o randomness.o training.o network.o neurons.o
+	gcc -Wall $^ -o myprogram -lm
+
+%.o : %.c
+	gcc -Wall $< -c
+
 send :
 	git add .
 	git commit
diff --git a/activations.c b/activations.c
index 91503ab..254ec63 100644
--- a/activations.c
+++ b/activations.c
@@ -1,13 +1,14 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <math.h>
+#include "activations.h"
 
 float sigmoid(float weighted_sum)
 {
-    return 1.0 / (1 + exp(-(float)weighted_sum));
+    return 1.0 / (1 + exp(-weighted_sum));
 }
 
 float sigmoid_derivative(float output)
 {
-    return 1.0;
+    return sigmoid(output) * (1 - sigmoid(output));
 }
\ No newline at end of file
diff --git a/activations.h b/activations.h
index 4780681..2be3aed 100644
--- a/activations.h
+++ b/activations.h
@@ -2,6 +2,6 @@
 #define ACTIVATIONS_H
 
 float sigmoid(float weighted_sum);
-float sigmoid_derivative(float output)
+float sigmoid_derivative(float output);
 
 #endif
\ No newline at end of file
diff --git a/activations.o b/activations.o
new file mode 100644
index 0000000..0416b71
Binary files /dev/null and b/activations.o differ
diff --git a/exe b/exe
deleted file mode 100755
index 8a3772d..0000000
Binary files a/exe and /dev/null differ
diff --git a/main.c b/main.c
index 8d0276b..cd1f742 100644
--- a/main.c
+++ b/main.c
@@ -4,10 +4,12 @@
 #include "randomness.h"
 #include "neurons.h"
 #include "network.h"
+#include "activations.h"
+#include "training.h"
 
 int main(int argc, char *argv[])
 {
-    init_randomness();
+    //init_randomness();
 
     printf("Bonjour et bienvenu ;)\n");
     int i;
@@ -15,6 +17,11 @@ int main(int argc, char *argv[])
     {
         printf("%dth generated fload = %f\n", i, random_float(0.0 , 1.0));
     }*/
+    printf("sigmoid(%f) = %f\n",0.5, sigmoid(0.5));
+    printf("sigmoid_derivative(%f) = %f\n",0.8, sigmoid_derivative(0.8));
 
+    /*float a=5.0;
+    printf("%f\n", (float)exp((double)a));*/
+    
     return 0;
 }
\ No newline at end of file
diff --git a/main.o b/main.o
new file mode 100644
index 0000000..02e92c9
Binary files /dev/null and b/main.o differ
diff --git a/myprogram b/myprogram
new file mode 100755
index 0000000..3b7afa1
Binary files /dev/null and b/myprogram differ
diff --git a/network.c b/network.c
index aebd110..8d7f26c 100644
--- a/network.c
+++ b/network.c
@@ -5,15 +5,70 @@
 #include "neurons.h"
 #include "network.h"
 
-Neuron *generate_layer(int n_neurons, int n_neurons_prev_layer)
+Neuron *generate_layer(int n_neurons, int n_neurons_prev_layer, char *activation_function)
 {
+    Neuron *first=NULL, *last=NULL;
+    int i;
+    for(i=1 ; i<=n_neurons ; i++)
+    {
+        Neuron *n = init_neuron(n_neurons_prev_layer, activation_function);
+        if(i==1)
+        {
+            first = n;
+            last = n;
+        }else
+        {
+            last->same_layer_next_neuron = n;
+            last = n;
+        }
+    }
 
+    return first;
 }
 
-Network *init_network(int n_neurons_per_layer[])
+Network *init_network(int n_neurons_per_layer[], int n_layers, char *activation_function_per_layer[])
 {
     /* initialize the network based on array n_neurons_per_layer :
-    - size of n_neurons_per_layer is the number of layers
+    - n_layers is simply the size of array n_neurons_per_layer
     - each ith number in array n_neurons_per_layer is the number of neurons in ith layer
+    - array activation_function_per_layer must be of same size as n_neurons_per_layer
     */
+   Network *network = (Network*)malloc(sizeof(Network));
+   network->n_layers = n_layers;
+   network->neurons_per_layer = (int*)malloc(n_layers * sizeof(int));
+   network->layers_first_neurons = (Neuron**)malloc(n_layers * sizeof(Neuron*));
+   int i;
+   for(i=0 ; i<n_layers ; i++)
+   {
+       network->neurons_per_layer[i] = n_neurons_per_layer[i];
+       if(i==0)
+       {
+           network->layers_first_neurons[i] = generate_layer(n_neurons_per_layer[i], 0, activation_function_per_layer[i]);
+       }else
+       {
+           network->layers_first_neurons[i] = generate_layer(n_neurons_per_layer[i], n_neurons_per_layer[i-1], activation_function_per_layer[i]);
+       }
+   }
+
+   return network;
+}
+
+void print_network(Network *network)
+{
+    
+}
+
+void destroy_network(Network *network)
+{
+    int i;
+    Neuron *temp;
+    for(i=0 ; i<network->n_layers ; i++)
+   {
+       while(network->layers_first_neurons[i] != NULL)
+       {
+           temp = network->layers_first_neurons[i];
+           network->layers_first_neurons[i] = temp->same_layer_next_neuron;
+           destroy_neuron(temp);
+       }
+   }
 }
\ No newline at end of file
diff --git a/network.h b/network.h
index 3fe68eb..e1d9b33 100644
--- a/network.h
+++ b/network.h
@@ -4,12 +4,15 @@
 typedef struct network Network;
 struct network
 {
-    Neuron *layers_first_neurons; //first neuron of each layer of the network
-    //Neuron *layers_last_neurons; //last neuron of each layer of the network
+    int n_layers;
     int *neurons_per_layer; //keeps track of number of layers' neurons
+    Neuron **layers_first_neurons; //pointers on first neuron of each layer of the network
+    //Neuron *layers_last_neurons; //last neuron of each layer of the network
 };
 
-Neuron *generate_layer(int n_neurons, int n_neurons_prev_layer);
-Network *init_network(int n_neurons_per_layer[]);
+Neuron *generate_layer(int n_neurons, int n_neurons_prev_layer, char *activation_function);
+Network *init_network(int n_neurons_per_layer[], int n_layers, char *activation_function_per_layer[]);
+void print_network(Network *network);
+void destroy_network(Network *network);
 
 #endif
\ No newline at end of file
diff --git a/network.o b/network.o
new file mode 100644
index 0000000..937f738
Binary files /dev/null and b/network.o differ
diff --git a/neurons.c b/neurons.c
index e16ba86..5974268 100644
--- a/neurons.c
+++ b/neurons.c
@@ -3,8 +3,9 @@
 #include <string.h>
 #include "randomness.h"
 #include "neurons.h"
+#include "activations.h"
 
-Neuron *init_neuron(int n_weights)
+Neuron *init_neuron(int n_weights, char *activation_function)
 {
     Neuron *neuron = (Neuron*)malloc(sizeof(Neuron));
     if(n_weights == 0)
@@ -21,6 +22,15 @@ Neuron *init_neuron(int n_weights)
     }
     neuron->bias = random_float(0.0 , 1.0);
     neuron->output = 0.0;
+    if(strcmp(activation_function, "nothing") == 0)
+    {
+        //to be completed later with tanh, relu, etc : for now only sigmoid is supported and will be the default function
+    }
+    else
+    {
+        neuron->activation = sigmoid;
+        neuron->activation_derivative = sigmoid_derivative;
+    }
     neuron->delta_error = 0.0;
     neuron->same_layer_next_neuron = NULL;
 
diff --git a/neurons.h b/neurons.h
index 3fe3200..6be8b2d 100644
--- a/neurons.h
+++ b/neurons.h
@@ -7,11 +7,13 @@ struct neuron
     float *weights; //weights associated to the neuron
     float bias; //neuron's bias
     float output; //output of the neuron
+    float (*activation)(float);
+    float (*activation_derivative)(float);
     float delta_error; //the delta error for updating current weights
     Neuron *same_layer_next_neuron;
 };
 
-Neuron *init_neuron(int n_weights);
+Neuron *init_neuron(int n_weights, char *activation_function);
 void destroy_neuron(Neuron *neuron);
 
 
diff --git a/neurons.o b/neurons.o
new file mode 100644
index 0000000..581ad50
Binary files /dev/null and b/neurons.o differ
diff --git a/randomness.o b/randomness.o
new file mode 100644
index 0000000..5de73a7
Binary files /dev/null and b/randomness.o differ
diff --git a/training.c b/training.c
index e69de29..01b0775 100644
--- a/training.c
+++ b/training.c
@@ -0,0 +1,7 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "randomness.h"
+#include "neurons.h"
+#include "activations.h"
+
diff --git a/training.h b/training.h
index e69de29..ddbb6e9 100644
--- a/training.h
+++ b/training.h
@@ -0,0 +1,6 @@
+#ifndef TRAINING_H
+#define TRAINING_H
+
+
+
+#endif
\ No newline at end of file
diff --git a/training.o b/training.o
new file mode 100644
index 0000000..7e37f31
Binary files /dev/null and b/training.o differ