Subject: PS to Nbody simulations

From: Jim Scott <[email-masked]>
Date: Fri, 14 Apr 1995 12:53:10 -0400 (EDT)

Jimmy the Moose
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Oh.  I meant to say.  With the numbers I gave you, things 
aren't going to happen very fast.  Not at 1/10th a second
per iteration.  Or even 1 second.

The way we ran these was printing out the galaxies every 
(i think it was) 100,000 seconds for when the galaxies were
close together, 1,000,000 seconds when far apart (use
a characteristic scale length of 10 galaxy radii for
dteremining far and near).  We used 1/10th second
for stepping time.  We really wanted 1/1000th, but on the
ol' Sun 3/50 .....

Anyway, how 'bout telling people to print out every X step
instead of every.  And then use DPU_TIMER for the 100,000
seconds to compare peoples alogrithms?  This way, too, the
print out loop no longer dominates the timing...

James H. Scott                              [email-masked]  
NASA Center for Computational Sciences 
   (NCCS)
Goddard Space Flight Center
Greenbelt, Maryland