R: help on Octave

[Pierpaolo]

Sure...

A small part of code is:

#####################################
dimxtot = 49;  #numero nodi in x*) 
dimytot = 49; #numero nodi in y*) 
dy = 1/(dimytot - 1);   #rpasso in y*)
dd = dimxtot*dimytot; #scrittura sintetica*)
r = dx/dy;  #rapporto fra i passi*)
cicli=10;
t0 = clock ();
w=zeros(3*dimxtot*dimytot,3*dimxtot*dimytot);

for j = 3:(dimytot-1 -1)
        for i = 3:(dimxtot-1 -1) 
   w((j-1)*dimxtot+(i),(j-1)*dimxtot+(i)) = 6 + 6*r^4 + 8*(r^2);
   w((j-1)*dimxtot+(i),(j-1)*dimxtot+(i-2))= 1;   
   w((j-1)*dimxtot+(i),(j-1)*dimxtot+(i-1))=-4-4*(r^2);    
   w((j-1)*dimxtot+(i),(j-1)*dimxtot+(i+1))=-4-4*(r^2);   
   w((j-1)*dimxtot+(i),(j-1)*dimxtot+(i+2))=1;   
   w((j-1)*dimxtot+(i),(j-1-1)*dimxtot+(i-1))=2*r^2;     
   w((j-1)*dimxtot+(i),(j-1-1)*dimxtot+(i))=-4*r^4 -4*r^2;     
   w((j-1)*dimxtot+(i),(j-1-1)*dimxtot+(i+1))=2*r^2;   
   w((j-1)*dimxtot+(i),(j-1+1)*dimxtot+(i-1))=2*r^2;
   w((j-1)*dimxtot+(i),(j-1+1)*dimxtot+(i))=-4*r^4-4*r^2;
   w((j-1)*dimxtot+(i),(j-1+1)*dimxtot+(i+1))=2*(r^2);
   w((j-1)*dimxtot+(i),(j-1-2)*dimxtot+(i))=1*(r^4);  
   w((j-1)*dimxtot+(i),(j-1+2)*dimxtot+(i))=1*(r^4);
        endfor
endfor
###################################

With 3*dimxtot*dimytot about 6200 I've memory error.

a=rand(6200) does not give any error
a=rand(8700) generates memory error

-----Messaggio originale-----
Da: Martin Helm [mailto:address@hidden 
Inviato: martedì 26 giugno 2012 15:56
A: Jordi Gutiérrez Hermoso
Cc: address@hidden; Pierpaolo
Oggetto: Re: help on Octave

Am 26.06.2012 15:52, schrieb Jordi Gutiérrez Hermoso:
> Oops, I made the wrong computation. I blame memroy fragmentation now.
> - Jordi G. H. 
;) happened to me often enough (wrong calculations)

I have some doubts, even if memory is fragmented it will just allocate
that memory in the windows paging file.

@Pierpaolo:
Can you show us a short code snippet which leads to that problem?
Does something as simple as

a = rand(6200)

show the same problem?