(j3.2006) (SC22WG5.4105) [ukfortran] Standard intrinsics and coarrays

Malcolm Cohen malcolm
Thu Oct 22 01:16:31 EDT 2009

Aleksandar Donev wrote:
> In the case of a "shared" generator, I am not sure I understand exactly what 
> is meant, guaranteed, or processor dependent. Is it obvious to others and I am 
> just being dense?

Yes it is obvious.

In a "shared" generator there is a single seed and a single sequence.  Images 
take values from that single sequence.

In a "separate" generator, each image has a seed and a sequence.  Each image 
takes values from its own sequence.

It is trivial to discover this by careful syncing between two images and a 
sequence of random_seed and random_number calls.

>    It is processor dependent whether all images use a common
>    generator or whether each image uses a separate one.

Perhaps we should require that it should be one or the other.

................................Malcolm Cohen, Nihon NAG, Tokyo.

More information about the J3 mailing list