Re: [ublas] Matrix Size/ Memory

From: Sebastian Gesemann (s.gesemann_at_[hidden])
Date: 2008-01-26 05:58:05

On Jan 26, 2008 11:46 AM, nisha kannookadan <nishak44_at_[hidden]> wrote:
>
> Hi Peter
>
> > Have you checked, that you are not using 4byte integer?,
>
> I acctually use double.
> > as 2^(7*5) needs 35 bits, so you long ints.
>
> I didnt get this calculation. How can I check, how many entires fit in 32 GB RAM maximally.

2^7 is roughly 128
2^(7*5) is roughly 127^5

Actualy you need about 2^(7*5+2) doubles for a 127^5 x 5 matrix. So
you need to use 64 bit integers for addressing the matrix' entries.
Also 2^(7*5+2) doubles make 2^(7*5+2+3) bytes which is about 128 Gigs.
Am I wrong?

Cheers!
SG