[MPI3 Fortran] Non-contiguous arrays (was Re: Argument data sizes)

[Iain Bason]

On Sep 18, 2008, at 1:13 PM, Jeff Squyres wrote:

> How else would you do it efficiently for non-contiguous datatypes  
> without a copy (which would be quite Bad for multiple reasons,  
> especially for very large datasets)?  Such issues are certainly not  
> unique to C (even in very large Fortran arrays, particularly if you  
> want to send just a plane from the middle of a 3D array, or  
> somesuch).  As another example of where datatypes are useful: with  
> the Fortran equivalent of C structs, you need to build up a composed  
> datatype to describe the message that you want to send/receive.

Didn't this come up in another thread?  In Fortran, you can use  
assumed shape arrays to pass these sorts of data without copying.  It  
would be nice if MPI could take advantage of that in order to make  
life easier for Fortran programmers.

Iain