def feature_normalization(X):
    """
    Mean/standard deviation normalization.
    
    :param np.ndarray X: Feature matrix to be normalized.
    :return: np.ndarray of normalized feature matrix, np.ndarray of means and np.ndarray of standard deviation.
    """
    mu = X.mean(axis=0)
    sigma = X.std(axis=0, ddof=1)
    return (X - mu) / sigma, mu, sigma