Re: new filter proposal
Rajeev Thakur (thakur@mcs.anl.gov)
Thu, 17 Apr 1997 11:48:48 -0500
> Date: Thu, 17 Apr 1997 09:42:01 -0700
> From: johnmay@llnl.gov (John May)
>
> Rajeev Thakur writes:
> > This raises another question.
> > Sec. 10.5.1 on pg 240 says that to ensure file interoperability, the
> > etype must be a "portable" datatype constructed out of contig, vector,
> > indexed, indexed_block, subarray, and darray type constructors.
> > Shouldn't that restriction also apply to filetypes?
>
> I think you're right. If etypes can stretch and shrink, then
> filetypes have to also. Thanks for pointing out Sec 10.5.1;
> I didn't realize that someone else had already worried about
> this problem.
>
> John
Well that leads to the real question I had.
If MPI_Type_struct cannot be used to create a filetype in
heterogeneous env., how does one specify holes in the file with lb and
ub? One may be able to specify lb with MPI_Type_resize (even that's
not clear), but what about ub?
Secondly, if my data structure in memory is an array of structures (in
C), how do I write it to the file?
Rajeev