help-octave
[Top][All Lists]

## Re: manipulating sparse matrices

 From: Andy Adler Subject: Re: manipulating sparse matrices Date: Sat, 15 Oct 2005 14:11:15 -0400 (EDT)

```On Sat, 15 Oct 2005, Mike Miller wrote:

> On Sat, 15 Oct 2005, David Bateman wrote:
>
> > nzmax is in 2.9, as the source-forge index was I believe based on a
> > 2.9.2 release, it should probably be updated soon as many things have
> > changed (eg statistics functions, etc). The 0bytes is a missing feature
> > in the octave-forge sparse functions as the bytes size in the whos
> > function I believe was added at 2.1.58, after the octave-forge sparse
> > stuff was written. Basically, it needs to implement a byte_size()
> > function to return the value that will be printed.. This also works in
> > 2.9.3
>
> For the meantime, stuck as I am in the 2.1.71 world (because I'm
> developing code for users who can install 2.1.71), can I estimate nzmax by
> taking 8*nnz()?  It seems that full matrices use 8 bytes per element.  Or
> maybe it should be 3*8*nnz() because every sparse element requires three
> terms: row, column and value.

A conservative estimate of memory would be 2*8*nnz(). Each sparse element
requires 2 ints and 1 double (+ a small amount of overhead - some
efficiencies of the compressed column format.

--

>
>
> > As you were asking about cholesky factorizations previously, I've just
> > gotten sparse cholesky factorizations working with cholmod and will
> > commit this soon, I want to try to address the chol2inv, cholinv and inv
> > functions, and update the docs first though...
>
> Excellent!
>
> You guys are great.  Thanks.
>
> I suppose that Octave 2.9.x will be released someday as Octave 3.0.
> Is that the plan?
>
> Mike
>
>
>
> -------------------------------------------------------------
> Octave is freely available under the terms of the GNU GPL.
>
> Octave's home on the web:  http://www.octave.org
> How to fund new projects:  http://www.octave.org/funding.html
> Subscription information:  http://www.octave.org/archive.html
> -------------------------------------------------------------
>
>

-------------------------------------------------------------
Octave is freely available under the terms of the GNU GPL.

Octave's home on the web:  http://www.octave.org
How to fund new projects:  http://www.octave.org/funding.html
Subscription information:  http://www.octave.org/archive.html
-------------------------------------------------------------

```