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Discreteness noise versus force errors in N-body simulationsA low accuracy in the force calculation per time step of a few percent for each particle pair is sufficient for collisionless N-body simulations. Higher accuracy is made meaningless by the dominant discreteness noise in the form of two-body relaxation, which can be reduced only by increasing the number of particles. Since an N-body simulation is a Monte Carlo procedure in which each particle-particle force is essentially random, i.e., carries an error of about 1000 percent, the only requirement is a systematic averaging-out of these intrinsic errors. We illustrate these assertions with two specific examples in which individual pairwise forces are deliberately allowed to carry significant errors: tree-codes on supercomputers and algorithms on special-purpose machines with low-precision hardware.
Document ID
19930037629
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Hernquist, Lars
(Lick Observatory Santa Cruz, CA, United States)
Hut, Piet
(Inst. for Advanced Study Princeton, NJ, United States)
Makino, Jun
(Tokyo Univ. Japan)
Date Acquired
August 16, 2013
Publication Date
January 10, 1993
Publication Information
Publication: Astrophysical Journal, Part 2 - Letters
Volume: 402
Issue: 2
ISSN: 0004-637X
Subject Category
Numerical Analysis
Accession Number
93A21626
Funding Number(s)
CONTRACT_GRANT: NAGW-2422
CONTRACT_GRANT: MOESC-03044032
CONTRACT_GRANT: NSF AST-90-18526
Distribution Limits
Public
Copyright
Other

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