Re: Building octave with large matrices support

[Jaroslav Hajek]

On Mon, Aug 24, 2009 at 10:12 PM, Rishi Amrit<address@hidden> wrote:
> Hi,
>
>    I'm trying to build octave to use large matices (>2GB). I read the note
> on http://wiki.octave.org/wiki.pl?EnableLargeArrays
>
> I'm running 64 bit Ubuntu, with BLAS, LAPACK, ARSUITE, SUITESPARSE etc
> installed from repositories. Just wondering do I need to build all these
> again from scratch before building octave with the instructions given on the
> above link ? Or by just enabling 64 bit flag in configuration of octave
> would work ?
>
> Thanks,
>

Yes, that is essential. Octave's index type (octave_idx_type) must
match the Fortran default integer, otherwise you'll see failures (even
segfaults). Also, there's currently no way to use a mixture (say,
32-bit BLAS with 64-bit SuiteSparse and 64-bit Octave) - that would be
straightforward but big and tedious change (you'd need to specify a
separate index type for each library and let configure sort it all
out).
This also is why 64-bit builds get little testing - nobody actually
uses them, so expect problems if you go that way.

You should also note that the limit is 2e9 elements, not 2GB - e.g.
for doubles it's 16GB, actually.

hth

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