[Beowulf] Win64 Clusters!!!!!!!!!!!!
toon at moene.indiv.nluug.nl
Sun Apr 8 13:30:41 EDT 2007
Jon Forrest wrote:
> One thing I've noticed about 64-bit computing in general
> is that it's being oversold. The **only** reason
> for running in 64-bit mode is if you need the additional
> address space.
I wouldn't be to sure of that. Recently I became interested in the
divisors of a given natural number.
The obvious Fortran program is:
integer*8 n, i, j, k
read(arg, '(i20)') n
i = n
j = 1
k = i / j
do while (k .ge. j)
if (i .eq. k * j) print*, k, j
j = j + 1
k = i / j
[ OK, this isn't purely Fortran 77, but close enough that
most compilers will do the *right thing* ]
I tried it on 32 bit Linux (at work) and my laptop (AMD64 Linux), using
The execution time difference was about 2 orders of magnitude.
Toon Moene - e-mail: toon at moene.indiv.nluug.nl - phone: +31 346 214290
Saturnushof 14, 3738 XG Maartensdijk, The Netherlands
At home: http://moene.indiv.nluug.nl/~toon/
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