Re: tril/triu not preserving sparseness

[David Bateman]

Martijn van Oosterhout wrote:
> 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,
>   
This works correctly in Octave 3.0

D.


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David Bateman                                address@hidden
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