[MPIWG Fortran] Question about an argument of MPI_Testall

Jeff Squyres (jsquyres) jsquyres at cisco.com
Wed Mar 12 10:30:43 CDT 2014


Rolf R. just reminded me off-list what the real reason is: MPI_STATUSES_IGNORE.

We can't know what the (count) will be, but you still must be able to pass MPI_STATUSES_IGNORE through that dummy argument.  Hence, it must be (*), not (count).

Keep in mind that the spec prohibits you from having a special type for MPI_STATUSES_IGNORE.  I.e., it must be Type(MPI_Status) so that tools can know how to intercept it properly.

Make sense?


On Mar 12, 2014, at 5:25 AM, N.M. Maclaren <nmm1 at cam.ac.uk> wrote:

> On Mar 12 2014, Malcolm Cohen wrote:
>> 
>> That reason is bogus, if the dummy argument is declared to have "count" elements the actual argument is required to have at least "count" elements, but this need not be exact. The Fortran standard states
>> 
>> "The rank and shape of the actual argument need not agree with the rank and shape of the dummy argument, but the number of elements in the dummy argument shall not exceed the number of elements in the element sequence of the actual argument."
>> 
>> (F2008 12.5.1.11)
> 
> And that has been true since Fortran II - I have just checked that it
> was explicitly stated there, too.
> 
> 
> Regards,
> Nick Maclaren.
> 
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-- 
Jeff Squyres
jsquyres at cisco.com
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