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[Scalapack] determinism in pzheevd


Is PZHEEVD deterministic? By that I mean, if I fix the input matrix and run 
PZHEEVD repeatedly on a fixed number of MPI tasks on the same architecture will 
I get the same result to machine precision every time. Let's assume everything 
is single-threaded, e.g. no threaded BLAS.

After some discussion, with a vendor (IBM) and the MPICH2 developers I am told 
that collectives are deterministic. 

After taking a closer look at PZHEEVD, the only non-deterministic behavior I 
see is in the routine PZHETRD which uses BI_TreeComb which itself does not look 
deterministic from the use of MPI_ANY_SOURCE (define to the variable BANYNODE).

Is there a deterministic version of BI_TreeComb available?

Nichols A. Romero, Ph.D.
Argonne Leadership Computing Facility
Argonne National Laboratory
Building 240 Room 2-127
9700 South Cass Avenue
Argonne, IL 60490
(630) 252-3441

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