code: def fast_logdet(A):
      """Compute log(det(A)) for A symmetric
  
      Equivalent to : np.log(nl.det(A)) but more robust.
      It returns -Inf if det(A) is non positive or is not defined.
      """
      sign, ld = np.linalg.slogdet(A)
      if not sign > 0:
          return -np.inf
      return ld
  
imports: from __future__ import division
  from functools import partial
  import warnings
  import numpy
  from scipy import linalg
  from scipy.sparse import issparse, csr_matrix
  from .None import check_random_state
  from .fixes import np_version
  from ._logistic_sigmoid import _log_logistic_sigmoid
  from ..externals.six.moves import xrange
  from .sparsefuncs_fast import csr_row_norms
  from .validation import check_array
  from ..exceptions import NonBLASDotWarning
label_desc: Use image node_id 4 for calling a global function with example usage: fast_logdet(A) and returns: ld, unknown