[Octave-bug-tracker] [bug #36562] Sparse matrix operations with NaN do not follow IEEE standard

[Rik]

Update of bug #36562 (project octave):

                  Status:                    None => Confirmed              
                 Summary: NaN/Inf behaviour unexpected in sparse rdivide =>
Sparse matrix operations with NaN do not follow IEEE standard

    _______________________________________________________

Follow-up Comment #1:

Confirmed on a recent (5/31/12) development tip.

The issue is more general than just divide so I have changed the bug Summary.

At present, I can verify that multiply and divide are affected while addition
and subtraction behaves correctly.

The issue appears to be a side effect of the way that sparse matrices improve
calculation performance.  In general, math operations like multiply and divide
only need to be performed on the non-zero elements of a sparse matrix. 
However, a NaN is different and should affect all elements of the matrix.

Below is some simple code to illustrate the problem.


Mfull = [1 0; 0 3];
Msparse = sparse (Mfull);

NaN .* Mfull
ans =

   NaN   NaN
   NaN   NaN

NaN .* Msparse
ans =

Compressed Column Sparse (rows = 2, cols = 2, nnz = 2 [50%])

  (1, 1) -> NaN
  (2, 2) -> NaN

NaN ./ Mfull
ans =

   NaN   NaN
   NaN   NaN

NaN ./ Msparse

ans =

   NaN  -Inf
  -Inf   NaN





    _______________________________________________________

Reply to this item at:

  <http://savannah.gnu.org/bugs/?36562>

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