def METHOD_NAME(mu_a, sigma_a, mu_b, sigma_b):
  """Non-batch KL for N(mu_a, sigma_a), N(mu_b, sigma_b)."""
  # Check using numpy operations
  # This mostly repeats the tensorflow code _kl_mvn_mvn(), but in numpy.
  # So it is important to also check that KL(mvn, mvn) = 0.
  sigma_b_inv = np.linalg.inv(sigma_b)
  t = np.trace(sigma_b_inv.dot(sigma_a))
  q = (mu_b - mu_a).dot(sigma_b_inv).dot(mu_b - mu_a)
  k = mu_a.shape[0]
  l = np.log(np.linalg.det(sigma_b) / np.linalg.det(sigma_a))
  return 0.5 * (t + q - k + l)