From help-octave-request at bevo dot che dot wisc dot edu  Thu Oct 23 10:51:27 1997
Subject: Memory limits
From: John Logsdon <j dot logsdon at lancaster dot ac dot uk>
To: help-octave at bevo dot che dot wisc dot edu
Date: Thu, 23 Oct 1997 00:54:12 +0100 (BST)

Dear octave-ists

Probably because I am greedy (!), and octave is so robust and excellent, I
push it at the edges.  Don't we all.

Recently, I have occasionally run out of memory with 2.0.9 linux version
(rh4.1) on a 64Mb m/c with 70Mb swap space.  I am using a lot of space -
top indicates generally 37M and up to about 45M.  When I load the data up,
it takes about 10-12M, which is about right.  I have a number of vectors
about 250000 long! 

I realise of course that calcs generally take up temporary storage but
even so I have worked out that when nothing is being done, there is
sometimes more space allocated than necessary, particularly in the memory
and swap allocation reported by top.

i  Is this a known feature?

ii Can I garbage collect from within octave (rather than saving, quitting
and restarting)?  Once the program dumped itself in octave-core only I
found that the data local to the function being run was dumped and none of
the main data.  I have trawled the info files and can find nothing
documented.

iii Could it be a feature of linux RH4.1 rather than octave?  If it is a
feature of RH4.1, can I garbage collect from root in another shell? 

My interim solution is to up my swap space to 250Mb or 500Mb which I will
do shortly by putting a 2.5Gb drive in but I think this is not the right
thing to do.  There are no other processes going (well, if you discount
the usual stuff, X and a few remote logins to track my email).  I can't at
the moment increase the physical memory.

BTW are there any plans to implement either sparse matrices or
byte/word/integer (1,2,4 byte) storage for data which are indices or take
restricted values in octave? 8 bytes to store small numbers is rather
wasteful - and yes I have thought about using sets.  

John

John Logsdon                               "Try to make things as simple
J dot Logsdon at lancaster dot ac dot uk                   as possible, but not simpler" 
Centre for Applied Statistics               a dot einstein at relativity dot org