def construct_kernel(self, metric):
    'Construct a Matern kernel covariance matrix, for \nu=3/2.\n        '
    (a, l) = (self.params['amplitude'], self.params['length'])
    Sigma = ((np.sqrt(3) * np.abs((metric[:, None] - metric[None, :]))) / l)
    Sigma = (((a ** 2) * (1 + Sigma)) * np.exp((- Sigma)))
    return Sigma
Construct a Matern kernel covariance matrix, for 
u=3/2.
def construct_kernel(self, metric):
    'Construct a Matern kernel covariance matrix, for \nu=3/2.\n        '
    (a, l) = (self.params['amplitude'], self.params['length'])
    Sigma = ((np.sqrt(3) * np.abs((metric[:, None] - metric[None, :]))) / l)
    Sigma = (((a ** 2) * (1 + Sigma)) * np.exp((- Sigma)))
    return Sigma