[MPIWG Fortran] Assumed-size array in MPI3

N.M. Maclaren nmm1 at cam.ac.uk
Mon Mar 10 12:23:35 CDT 2014

On Mar 10 2014, Bill Long wrote:
> I agree with Steve. In these sorts of calls the actual size of the array 
> is available from somewhere else - either another argument or information 
> in the communicator. This is the common situation when calling C.

I don't, but only in the slant of my comment.  I would say that assumed
size arrays should be used ONLY when calling facilities that use a C-like
interface (which obviously includes MPI 2.2).  While it would be nice to
say that programs should always use the new MPI 3.0 interfaces, currently
their availability is patchy and unreliable.  So the book over-simplifies,
but I agree with its recommendation for pure Fortran code.

There are other reasons to use assumed size, but they are mostly pretty


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