[Octave-bug-tracker] [bug #53869] Residue returning an inaccurate result

[Rik]

Update of bug #53869 (project octave):

                  Status:               Need Info => Confirmed              

    _______________________________________________________

Follow-up Comment #4:

Confirmed.  Calling residue_bug with n = 1,2 works fine.  However, with n = 3
there is already a warning printed and the condition number of the matrix is
scarily high.


octave:6> debug_on_warning (1)
octave:7> residue_bug (3)
warning: matrix singular to machine precision, rcond = 5.73398e-20
warning: called from
    residue at line 265 column 5
    residue_bug at line 6 column 11
stopped in /home/rik/wip/Projects_Mine/octave-dev/scripts/polynomial/residue.m
at line 265
265:   r = A \ B;


The residue algorithm is coded as an m-file so it should be easy to see why A
is nearly singlular.  However, I don't understand the algorithm well enough to
say how it should be modified or replaced.


    _______________________________________________________

Reply to this item at:

  <http://savannah.gnu.org/bugs/?53869>

_______________________________________________
  Message sent via Savannah
  https://savannah.gnu.org/