(j3.2006) (SC22WG5.5931) Comments on some of the comments

John Reid John.Reid
Fri Aug 11 05:42:23 EDT 2017

Malcolm Cohen wrote:
> John Reid writes:
>> An underlying assumption of HPC has always been that the team values on
>> the images of a team would differ from image to image.
> Sorry, but I cannot agree with this.  Where has coarray TS said anything
> that might imply this?  I see nowhere, and the technical effect of what it
> does state implies the opposite!

See the last sentence of 5.1, para 1: "Information about the team to 
which the current image belongs can be determined by the processor from 
the collective value of the team variables on the images of the team."

According to the TS, this should have been copied to 2.3.4, now 5.2.4, 
but it seems to have disappeared.

Yes, we have goofed in not making the intention clearer.

Best wishes,


> It might have been in some people's minds, but it is counter to various
> things I have heard other people involved in HPC say.  Perhaps they were all
> mistaken, but...
> Moreover, it would have been very easy (trivial in fact) to make a team
> variable "differ from image to image", BUT THIS WAS NEVER DONE.  According
> to the coarray TS and the draft standard you can assign team variables from
> one image to another AND THIS DOES NOT CHANGE THE VALUE, so it still
> identifies the same team.
> Such a fundamental upheaval in the model is simply unacceptable.  Those who
> have already started to implement teams according to the coarray TS, as
> modified by the tweaks we have made later, are going to be very annoyed they
> have to restart their design.
> If you are serious, in my opinion this mean you should be voting NO on the
> CD and going back to the beginning.  Oh, and stop calling it Fortran 2015 as
> this is a fundamental change.  Fortran 2017 (assuming we can actually reach
> agreement this year!) is what it should be.
> I cannot believe that we are revisiting fundamental design issues years
> after publication of the TS and when we are supposedly so far advanced in
> standardising F2015.
> Finally,
>> This what the changes aim to ensure.
> Right, that you can no longer use GET_TEAM fully is merely collateral
> damage.  Words like "you can not be serious" spring ineluctably to mind.
> Yours in despair,

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