Yup, that cleared it. Thanks.
-gideon
> On Feb 8, 2015, at 12:51 PM, Matthew Knepley <[email protected]> wrote:
>
> On Sun, Feb 8, 2015 at 11:43 AM, Gideon Simpson <[email protected]
> <mailto:[email protected]>> wrote:
> What should I make of the following warning, where I have used an
> MPI_Allreduce on a quantity computed on each processor.
>
> include -I/opt/local/include -I/opt/local/include/mpich-gcc48
> -I/opt/local/include `pwd`/petsc_trapz1.c
> In file included from /opt/local/lib/petsc/include/petscsys.h:1794:0,
> from /opt/local/lib/petsc/include/petscis.h:7,
> from /opt/local/lib/petsc/include/petscvec.h:9,
> from /Users/gideon/code/trapz/petsc_trapz1.c:3:
> /Users/gideon/code/trapz/petsc_trapz1.c: In function 'main':
> /opt/local/lib/petsc/include/petsclog.h:370:57: warning: value computed is
> not used [-Wunused-value]
> ((petsc_allreduce_ct += PetscMPIParallelComm(comm),0) ||
> MPI_Allreduce(sendbuf,recvbuf,count,datatype,op,comm))
> ^
> /Users/gideon/code/trapz/petsc_trapz1.c:110:3: note: in expansion of macro
> 'MPI_Allreduce'
> MPI_Allreduce(&local_trapz, &global_trapz, 1, MPI_DOUBLE, MPI_SUM,
> PETSC_COMM_WORLD);
>
> It looks like you are not checking the return code:
>
> ierr = MPI_Allreduce(&local_trapz, &global_trapz, 1, MPI_DOUBLE, MPI_SUM,
> PETSC_COMM_WORLD);CHKERRQ(ierr);
>
> Matt
>
>
> -gideon
>
>
>
>
> --
> What most experimenters take for granted before they begin their experiments
> is infinitely more interesting than any results to which their experiments
> lead.
> -- Norbert Wiener
