[OctDev] Re: sparse: size and indexing

[Andy A. <ad...@si...>]

On Sat, 27 Mar 2004, Schloegl Alois wrote:

> I'm using the latest CVS-versions of Octave and Octave-forge and observed
> two problems using SPARSE matrices.
>
> (1) size of a sparse matrix can not be obtained, [-1,-1] is returned.

I can't repeat this (with 2.1.57 and yesterday's octave-forge)
octave:1> which sparse
sparse is the dynamically-linked function from the file
/usr/lib/octave/2.1.57/site/oct/i386-pc-linux-gnu/octave-forge/sparse.oct
octave:2> x=sparse(2:31,1:30,1,31,30);
octave:3> size(x)
ans =
  31  30
octave:4> H.x=sparse(2:31,1:30,1,31,30);
octave:5> size(H.x)
ans =
  31  30

> (2) indexing of a sparse field within a struct stops with an error.

I don't believe that this has ever worked.

octave:6> H.x(2:4,:)
error: can't perform indexing operations for sparse type
octave:6> x(2:4,:)
ans = ...


I would like to try to fix (2) if possible. Could someone
explain to me if dynamically loaded types need to do anything
special to allow indexing in a struct?

andy