(j3.2006) (SC22WG5.4106) [ukfortran] Standard intrinsics and coarrays

[Van Snyder]

Malcolm Cohen wrote:
> Aleksandar Donev wrote:
>   
>>    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.
>   

If we require a single generator, it's difficult to get the same 
sequence on a particular image on consecutive runs, which is useful 
(some would say indispensible) for debogging, without specifying 
rigorous synchronization, which might be more rigorous than the problem 
needs.

If we require separate generators, one can get the effect of a single 
generator by having one image do the generation.  This might entail an 
inolerable performance penalty.

It looks like Hobson's choice, but we ought either to choose, to provide 
a mechanism for a program to choose, or require the processor to provide 
a mechanism, outside the language, to choose.

--
Van