docs: def plogdet(K):
      r"""Log of the pseudo-determinant.
  
      It assumes that ``K`` is a positive semi-definite matrix.
  
      Args:
          K (array_like): matrix.
  
      Returns:
          float: log of the pseudo-determinant.
      """
      egvals = eigvalsh(K)
      return npsum(log(egvals[egvals > epsilon]))