[Octave-bug-tracker] [bug #41065] Single precision matrix inverse gives bogus singular matrix warning

[John W. Eaton]

Follow-up Comment #5, bug #41065 (project octave):

Thinking about this a little more, I'm not sure the fix is the right thing to
do.  We want to test rcond+1 == 1 but in float precision for floats and double
precision for doubles.  What we are doing instead is always doing the test as
a double.  I think that's wrong.  For example:


octave:2> x = eps ('single')
x =  1.1921e-07
octave:3> x = eps ('single') / 2
x =  5.9605e-08
octave:4> x + 1 == 1
ans =  1
octave:5> double (x) + 1 == 1
ans = 0


I also think this is worth applying to stable.  It seems bad if Octave can't
even invert a simple float matrix without issuing a warning.  I checked in the
following change on stable and merged it with gui-release and default:

  http://hg.savannah.gnu.org/hgweb/octave/rev/36057e2411f8


    _______________________________________________________

Reply to this item at:

  <http://savannah.gnu.org/bugs/?41065>

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