On Fri, Nov 20, 2009 at 1:57 PM, Jaroslav Hajek <high...@gmail.com> wrote:
>
>
> On Fri, Nov 20, 2009 at 1:44 PM, Michael Creel <michael.cr...@uab.es>
wrote:
>>
>> Hi all,
>>
>> In another message, Jaroslav made the comment
>>
>>> 1. info is the first output argument in all functions. I think it should
>>> be the second one, so that it can be easily ignored if wanted.
>>> In particular, the check in examples
>>>
>>> if not(MPI_Initialized)
>>> info = MPI_Init();
>>> end
>>>
>>> makes no sense (unless I'm missing something) because it's the info
>>> output from MPI_Initialized that is tested and that is always zero.
>>
>> This follows the MPI standard, which says:
>>>
>>> All MPI routines (except MPI_Wtime and MPI_Wtick) return an error value;
>>> C routines as the value of the function and Fortran routines in the last
>>> argument. Before the value is returned, the current MPI error handler is
>>> called. By default, this error handler aborts the MPI job. The error
handler
>>> may be changed with MPI_Errhandler_set; the predefined error handler
>>> MPI_ERRORS_RETURN may be used to cause error values to be returned. Note
>>> that MPI does not guarentee that an MPI program can continue past an
error.
>>>
>>> MPI_SUCCESS No error; MPI routine completed successfully.
>>
>> Following the standard is a big plus, in my opinion. That way, knowledge
>> about MPI previously gained from C or Fortran will be useful when using
MPI
>> with Octave.
>
> Yes, my approach still follows the standard, it's just more convenient to
> use. The standard says nothing about how external bindings should behave.
>
Right, but MPI functions for C or Fortran don't return anything but things
like info, flag, status. The contents of messages passed back and forth are
not obtained from return values of functions. It's certainly possible to
place a received message into the output of a MPI_Recv binding, and there
may be a some logic to the idea, but it is a step away from the C and
Fortran way of doing things. Most people will learn about MPI though C and
Fortan tutorials, so following that syntax is not a bad idea. What would you
propose to use as outputs of functions?
M.
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