Newsgroups: comp.parallel.mpi
From: Jing Guo <guo@dao.gsfc.nasa.gov>
Subject: Reproducible MPI_reduce() algorithms?
Organization: NASA Goddard Space Flight Center -- Greenbelt, Maryland USA
Date: Mon, 23 Feb 1998 11:55:53 -0500
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Message-ID: <34F1AA19.237C@dao.gsfc.nasa.gov>

I need help on using MPI_reduce() with floating-point reduction 
arithmatics:

  1)  Is there documented knowledge about the reproducibility of, 
    e.g., MPI_reduce(...MPI_REAL,MPI_SUM,...), using the _same_ number 
    of PEs, for known MPI implementations?

  2)  How difficult is it to implement a floating-point reduction 
    algorithm to ensure reproducibility with _different_ numbers of 
    PEs?  Or where can one get those information?

Thank you for your time!

Jing
-- 
________________________________ _-__-_-_ _-___---
Jing Guo, guo@dao.gsfc.nasa.gov, (301)805-8333(o), (301)805-7960(fx)
Data Assimilation Office, Code 910.3, NASA/GSFC, Greenbelt, MD 20771