Re: Co-Array Fortran

On Oct 30, 6:41 pm, Dan Nagle <danna...@xxxxxxxxxxx> wrote:
Hello,

gary.l.sc...@xxxxxxxx wrote:
I think I understand basically, but not sure why it isn't often
important to know with certainty whether a coarray is local or not.
(performance?) If a coarray COULD be local (more or less), i might
structure the problem differently than if it might be indeterminately
local or remote.

A co-array element is local if and only if either:

There is no [] on the reference
-or-
The value of the index(es) indicates the this image

from walter spector

"a(i) = b(i) + c(i)[np]


The A and B references are local. But C is a coarray, and so would
load values from coarray process 'np'. (Which may or may not be local
-
depending on the value of np.) "

the last sentence seems to imply that with a [np] reference present,
it could denote either a local or remote reference depending on the
value. that superficially seem to conflict.





There are no other cases.

Note that co-arrays are defined in terms of images,
a similar question could be asked in terms of arrays
and cache lines. Both are beyond the standard.

--

Dan Nagle
Purple Sage Computing Solutions, Inc.


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