[Octave-bug-tracker] [bug #53390] lu factorization of large sparse matrices often fails

[Marco Caliari]

URL:
  <http://savannah.gnu.org/bugs/?53390>

                 Summary: lu factorization of large sparse matrices often
fails
                 Project: GNU Octave
            Submitted by: caliari
            Submitted on: Tue 20 Mar 2018 03:27:30 PM UTC
                Category: Octave Function
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Unexpected Error
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: dev
        Operating System: GNU/Linux

    _______________________________________________________

Details:

If you try


S = sprand  (1000, 1000, 1 / 1000);
[L, U] = lu (S);


quite often you get


error: lu: sparse_lu: numeric factorization failed


If you check the value of status around line 730 of sparse-lu.cc, you find it
is -11 which means (umfpack_numeric.h, umfpack.h)


The pattern (Ap and/or Ai) has changed since the call to
umfpack_*_*symbolic which produced the Symbolic object.


I don't see why it should have changed.




    _______________________________________________________

Reply to this item at:

  <http://savannah.gnu.org/bugs/?53390>

_______________________________________________
  Message sent via/by Savannah
  http://savannah.gnu.org/