Re: BLCR - changing code results ??

From: Paul H. Hargrove (PHHargrove_at_lbl_dot_gov)
Date: Tue Nov 01 2005 - 11:48:05 PST

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      I have no idea why your results would change, other than your theory
    on random numbers.  The cr_run script will LD_PRELOAD two libraries, the
    blcr library and the pthreads library.  I don't know of any reason why
    either one would have any direct effect on your simulation.  It is
    remotely possible that a different random number generator is being
    linked from the pthread library.  You could test this by modifying
    cr_run to LD_PRELOAD only the pthreads lib (and not to see if
    you still see modified results.
    Adolfo J. Banchio wrote:
    >Before I try to isolate the problem.
    >I'd like to ask you if it is possible to understand why
    >a code (a simulation) lunched using cr_run could
    >give differen results than when lunched directly.
    >If I run
    >I get different results than if I run
    >cr_run ./simul.x
    >Actually I noticed this since the difference seems to
    >be quite dramatic (I get particle overlap when using cr_run).
    >I'm trying to identify where the difference arise and isolate
    >the problem.
    >But I'm totally surprised that something like this could 
    >happen. May random numbers generation be affected?
    >(the simulation are compiled with Intel F90).
    >thanks for any comment,
    Paul H. Hargrove                          PHHargrove_at_lbl_dot_gov
    Future Technologies Group                 
    HPC Research Department                   Tel: +1-510-495-2352
    Lawrence Berkeley National Laboratory     Fax: +1-510-486-6900

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