R help - Oct 2009 - Huge matrix: allocation works but assignment fails

Hello everyone,

I am working with one big matrix:
w=matrix(0,18000,18000)

on a Linux computer with 16Go of RAM.

I can actually create the matrix, and even access elements:
w[10,10]
0

but if I try to change one element, it fails:
w[10,10]=1
Erreur : impossible d'allouer un vecteur de taille 2531250 Ko
(Failed to allocate a vector of size...)

What can I do? And, maybe even more important, how can one explains such 
a behavior?

Thank you for any help/advice

R?mi Proville.

Remi wrote:
> Hello everyone,
> 
> I am working with one big matrix:
> w=matrix(0,18000,18000)
> 
> on a Linux computer with 16Go of RAM.
> 
> I can actually create the matrix, and even access elements:
> w[10,10]
> 0
> 
> but if I try to change one element, it fails:
> w[10,10]=1
In this case your object is copied and you need two times the space for 
your object.

Best,
Uwe Ligges

> Erreur : impossible d'allouer un vecteur de taille 2531250 Ko
> (Failed to allocate a vector of size...)
> 
> What can I do? And, maybe even more important, how can one explains such 
> a behavior?
> 
> Thank you for any help/advice
> 
> R?mi Proville.
> 
> ______________________________________________
> R-help at r-project.org mailing list
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> PLEASE do read the posting guide 
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

> Remi wrote:
> 
> > (Failed to allocate a vector of size...)
> > What can I do? And, maybe even more important, how can one explains
such
> > a behavior?
 If your matrices are not sparse, get more memory. If they are,

 help("sparseMatrix",package=Matrix) ?