def dist_vect(data, num_datapoint1, num_datapoint2):
    """
    Returns the euclidean distance between the datapoints data[num_datapoint1,:] and
    data[num_datapoint2,:].
    """
    diff_vect = data[:,num_datapoint1] - data[:,num_datapoint2]
    #dist = np.linalg.norm(diff_vect)
    dist = diff_vect.T * diff_vect
    return dist