Re: [igraph] memory igraph

[Gábor Csárdi]

On Thu, Feb 4, 2010 at 1:26 PM, Raghavendra Singh
<address@hidden> wrote:
> Hi,
> I am using the C package for igraph-0.5.3
> I want to create a large random graph, using erdos_renyi_game GNP:
>
> N ~ 262144
> P ~ 0.5

The expected value of the number of edges is 17,179,803,648 in your
graph, that is, more than 17 billion edges. For this you need at least
17179803648 * 4 * 8 / 1000 / 1000 / 1000  = 549.7537 Gbytes of memory
(plus some extra for the vertices).

If you store them in a logical adjacency matrix, one bit for each
possible edge, then it fits into 17179803648 / 8 / 1000 / 1000 / 1000
= 2.1 Gbytes.

This is a (very) dense graph, igraph works well with sparse graphs.

Gabor

[...]

-- 
Gabor Csardi <address@hidden>     UNIL DGM