code: def logdet(self):
          
          self._init_svd()
          return -log(self._De).sum() + self.G.shape[0] * self.C1.logdet()
docs: Implements log|K| = - log|D| + n⋅log|C₁|.
  
          Returns
          -------
          logdet : float
              Log-determinant of K.