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Re: About diagonal matrices


From: Jaroslav Hajek
Subject: Re: About diagonal matrices
Date: Tue, 24 Feb 2009 14:52:23 +0100

On Tue, Feb 24, 2009 at 2:44 PM, dbateman <address@hidden> wrote:
>
> It's difficult to respond as I'm on a 3G phone. Octave never had this
> Behavior with sparse matrices until your recent changes.

What, my changes? I don't think I touched sparse matrices in this
regard. Or are you referring
to diagonal matrices? Then I'm confused with the rest...

> Try with 3.0.4 and see.

I see in 3.0.4:

NaN * speye (3)
ans =

Compressed Column Sparse (rows = 3, cols = 3, nnz = 3)

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

speye (3) * [NaN; 1; 1]

ans =

   NaN
     1
     1

i.e., exactly what we have now


> Even matlab now produces NaN values in recent versions. I still
> strongly consider the new behavior is wrong

Yes, that's a bug in Matlab, IMHO. Dunno why they did it. Note that
they didn't do it in the other cases.


-- 
RNDr. Jaroslav Hajek
computing expert
Aeronautical Research and Test Institute (VZLU)
Prague, Czech Republic
url: www.highegg.matfyz.cz


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