def initialize_weights(self):
        """Randomly initializes the visible-to-hidden connections."""
        n = self._outputSize
        m = self._inputSize
        self._Q = self._random.sample((n,m))

        # Normalize the weights of each units
        for i in range(n):
            self._Q[i] /=  np.sqrt( np.dot(self._Q[i], self._Q[i]) )
Randomly initializes the visible-to-hidden connections.