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Re: tril/triu not preserving sparseness
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From: |
Martijn van Oosterhout |
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Subject: |
Re: tril/triu not preserving sparseness |
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Date: |
Fri, 25 Jan 2008 13:11:13 +0100 |
On Jan 25, 2008 12:28 PM, David Bateman <address@hidden> wrote:
> Fixed in a later version of Octave... The relevant changelog entry is
>
> 2006-04-02 David Bateman <address@hidden>
>
> * general/tril.m, general.triu.m:
> Use resize (resize (x, 0), nr, nc) rather than zeros (nr, nc)
> to allow user types to work correctly.
That commit added the resize, which is the cause of my problems. It
only goes wrong for complex matrices. You're saying that something
else changed in octave so that the above works? Because on my machine
I get this:
octave:1> S=speye(1000); issparse(S)
ans = 1
octave:2> issparse( resize( resize(S,0),1000, 1000 ))
ans = 1
octave:3> S=speye(1000)*I; issparse(S)
ans = 1
octave:4> issparse( resize( resize(S,0),1000, 1000 ))
ans = 0
Anyway, I found another way of solving the problem. If I get around to
upgrading I'll try it out there... Thanks anyway.
Have a nice day,
--
Martijn van Oosterhout <address@hidden> http://svana.org/kleptog/