From help-octave-request at bevo dot che dot wisc dot edu  Tue Feb  8 21:58:19 2000
Subject: Re: memory problem
From: "John W. Eaton" <jwe at bevo dot che dot wisc dot edu>
To: Daniel Heiserer <Daniel dot Heiserer at bmw dot de>
cc: help-octave at bevo dot che dot wisc dot edu
Date: Tue, 8 Feb 2000 21:55:44 -0600 (CST)

On  2-Feb-2000, Daniel Heiserer <Daniel dot Heiserer at bmw dot de> wrote:

| jwe at bevo dot che dot wisc dot edu wrote:
|
| > On  1-Feb-2000, Daniel Heiserer <Daniel dot Heiserer at bmw dot de> wrote:
| > 
| > | octave:2> tic;eval(sprintf("L_%08d=eye(1000);",[1:1000]));toc
| > | error: memory exhausted -- trying to return to prompt
| > |
| > | .........
| > |  wd   matrix             1000   1000  L_00000232
| > |  wd   matrix             1000   1000  L_00000233
| > |
| > | ==> octave could create only 233 matrizes.
| >
| > That's about 233 * 1000 * 1000 * 8 ==> 1.8GB of data (unfortunately,
| > even though eye produces a diagonal matrix, Octave currently uses a
| > full matrix to store it).
| 
| I know. I have 16Gb of memory. :-)

OK, I tried your example on my system using the latest development
sources and also with a copy of 2.0.15, and both behaved the same, and
neither seemed to have the bug that you report.

My system only has 128MB of real memory and 128MB of swap allocated.
So, I would expect to be able to create about 25 1000x1000 matrices.
Thats 25 * 8 * 1000 * 1000 bytes, or about 190MB (there are a few
other things running on the system, so I can't expect to use all 256MB
of virtual memory).  When I tried it, I had no trouble creating 25
matrices, and the resulting size of Octave seemed reasonable, with a
total of 202560kB of virtual memory used.  When I tried to generate a
few more 1000x1000 matrices, I ran out of memory.  But Octave was not
using anything like 10 times the amount of memory that I would expect
it to.

If you or anyone else can reproduce the problem you are having, can
you please try to debug it and find out what is going on?

Thanks,

jwe



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