On 08/10/2018 01:27 PM, Jeff Squyres (jsquyres) via users wrote:
It is unlikely that MPI_MINLOC and MPI_MAXLOC will go away any time soon.

As far as I know, Nathan hasn't advanced a proposal to kill them in MPI-4, 
meaning that they'll likely continue to be in MPI for at least another 10 
years.  :-)

(And even if they did get killed in MPI-4, implementations like Open MPI would 
continue to keep them in our implementations for quite a while -- i.e., years)


Yeah!
Two thumbs up!


On Aug 10, 2018, at 1:13 PM, Diego Avesani <diego.aves...@gmail.com> wrote:

I agree about the names, it is very similar to MIN_LOC and MAX_LOC in fortran 
90.
However, I find difficult to define some algorithm able to do the same things.



Diego


On 10 August 2018 at 19:03, Nathan Hjelm via users <users@lists.open-mpi.org> 
wrote:
They do not fit with the rest of the predefined operations (which operate on a 
single basic type) and can easily be implemented as user defined operations and 
get the same performance. Add to that the fixed number of tuple types and the 
fact that some of them are non-contiguous (MPI_SHORT_INT) plus the terrible 
names. If I could kill them in MPI-4 I would.

On Aug 10, 2018, at 9:47 AM, Diego Avesani <diego.aves...@gmail.com> wrote:

Dear all,
I have just implemented MAXLOC, why should they  go away?
it seems working pretty well.

thanks

Diego


On 10 August 2018 at 17:39, Nathan Hjelm via users <users@lists.open-mpi.org> 
wrote:
The problem is minloc and maxloc need to go away. better to use a custom op.

On Aug 10, 2018, at 9:36 AM, George Bosilca <bosi...@icl.utk.edu> wrote:

You will need to create a special variable that holds 2 entries, one for the 
max operation (with whatever type you need) and an int for the rank of the 
process. The MAXLOC is described on the OMPI man page [1] and you can find an 
example on how to use it on the MPI Forum [2].

George.


[1] https://www.open-mpi.org/doc/v2.0/man3/MPI_Reduce.3.php
[2] https://www.mpi-forum.org/docs/mpi-1.1/mpi-11-html/node79.html

On Fri, Aug 10, 2018 at 11:25 AM Diego Avesani <diego.aves...@gmail.com> wrote:
  Dear all,
I have probably understood.
The trick is to use a real vector and to memorize also the rank.

Have I understood correctly?
thanks

Diego


On 10 August 2018 at 17:19, Diego Avesani <diego.aves...@gmail.com> wrote:
Deal all,
I do not understand how MPI_MINLOC works. it seem locate the maximum in a 
vector and not the CPU to which the valur belongs to.

@ray: and if two has the same value?

thanks


Diego


On 10 August 2018 at 17:03, Ray Sheppard <rshep...@iu.edu> wrote:
As a dumb scientist, I would just bcast the value I get back to the group and 
ask whoever owns it to kindly reply back with its rank.
      Ray


On 8/10/2018 10:49 AM, Reuti wrote:
Hi,

Am 10.08.2018 um 16:39 schrieb Diego Avesani <diego.aves...@gmail.com>:

Dear all,

I have a problem:
In my parallel program each CPU compute a value, let's say eff.

First of all, I would like to know the maximum value. This for me is quite 
simple,
I apply the following:

CALL MPI_ALLREDUCE(eff, effmaxWorld, 1, MPI_DOUBLE_PRECISION, MPI_MAX, 
MPI_MASTER_COMM, MPIworld%iErr)
Would MPI_MAXLOC be sufficient?

-- Reuti


However, I would like also to know to which CPU that value belongs. Is it 
possible?

I have set-up a strange procedure but it works only when all the CPUs has 
different values but fails when two of then has the same eff value.

Is there any intrinsic MPI procedure?
in anternative,
do you have some idea?

really, really thanks.
Diego


Diego

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