```On 26 Jun., 07:36, "Ron N." <rhnlo...@yahoo.com> wrote:
> On Jun 24, 10:52 pm, Rune Allnor <all...@tele.ntnu.no> wrote:
>
>
>
> > On 25 Jun, 07:19, maverickm...@gmail.com wrote:
>
> > > hi all,
> > >                             i am faced with a simple yet intriguing
> > > problem. i am running octave 2.1.73.
> > >  i am trying to multiply two matrices  (29004 x 120)   (120 x 29004)
> > > inside a program. octave simply quits when it executes the command. is
> > > there anything that i can do.
>
> > An NxM by MxN matrix multiplication produces a NxN matrix, or
> > 29004 x 29004 elements in your case. Assume each element to
> > take 8 bytes (16 if you are working with complex matrices) and
> > find that this simple expression requires a mere
>
> > 29004^2*8 = 6.7e9 bytes
>
> > or 6.7 GBytes of memory.
>
> That's assuming his matrices aren't extremely sparse.  There
> are algorithms that should use a lot less memory if there are
> only a small number of non-zero matrix elements in either matrix.
> Don't know if octave uses these algorithms.

Perhaps it went searching for them.

:-)

Regards,
Andor

```
```On Jun 24, 10:52 pm, Rune Allnor <all...@tele.ntnu.no> wrote:
> On 25 Jun, 07:19, maverickm...@gmail.com wrote:
>
> > hi all,
> >                             i am faced with a simple yet intriguing
> > problem. i am running octave 2.1.73.
> >  i am trying to multiply two matrices  (29004 x 120)   (120 x 29004)
> > inside a program. octave simply quits when it executes the command. is
> > there anything that i can do.
>
> An NxM by MxN matrix multiplication produces a NxN matrix, or
> 29004 x 29004 elements in your case. Assume each element to
> take 8 bytes (16 if you are working with complex matrices) and
> find that this simple expression requires a mere
>
> 29004^2*8 = 6.7e9 bytes
>
> or 6.7 GBytes of memory.

That's assuming his matrices aren't extremely sparse.  There
are algorithms that should use a lot less memory if there are
only a small number of non-zero matrix elements in either matrix.
Don't know if octave uses these algorithms.

IMHO. YMMV.
--
rhn A.T nicholson d.0.t C-o-M

```
```maverickmint@gmail.com writes:

> hi all,
>                             i am faced with a simple yet intriguing
> problem. i am running octave 2.1.73.
>  i am trying to multiply two matrices  (29004 x 120)   (120 x 29004)
> inside a program. octave simply quits when it executes the command. is
> there anything that i can do.

Upgrade to a version that's been released within the last three years.
I believe the current stable version is 2.9.9.

What platform are you running on?
--
%  Randy Yates                  % "Bird, on the wing,
%% Fuquay-Varina, NC            %   goes floating by
%%% 919-577-9882                %   but there's a teardrop in his eye..."
%%%% <yates@ieee.org>           % 'One Summer Dream', *Face The Music*, ELO
```
```On 25 Jun, 07:19, maverickm...@gmail.com wrote:
> hi all,
>                             i am faced with a simple yet intriguing
> problem. i am running octave 2.1.73.
>  i am trying to multiply two matrices  (29004 x 120)   (120 x 29004)
> inside a program. octave simply quits when it executes the command. is
> there anything that i can do.

An NxM by MxN matrix multiplication produces a NxN matrix, or
29004 x 29004 elements in your case. Assume each element to
take 8 bytes (16 if you are working with complex matrices) and
find that this simple expression requires a mere

29004^2*8 = 6.7e9 bytes

or 6.7 GBytes of memory.

What to do? Re-structure the algorithm so you avoid the whole
thing. Bumping into that sort of matrix expression is an almost
certain indicator that you did something wrong up-stream from
where the problem occurs.

Rune

```
```hi all,