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Foil 17 N-body Problem is a one dimensional Algorithm

From CPS615-End of N-Body Discussion and Beginning of Numerical Integration Delivered Lectures of CPS615 Basic Simulation Track for Computational Science -- 15 October 96. by Geoffrey C. Fox *
Secs 313.9
Also we used a one-dimension parallel decomposition
Note these one dimensional characteristics are independent of dimension of space that particles move in.
Normally d is thought of as dimension of physical space in which problem posed.
But the geometrical interpretation of d is only valid where interaction between particles is itself geometrical i.e. short range
Rather N body algorithm has no geometric structure and you see d=1 characteristic of algorithm
See Chapter 3 of Parallel Computing Works for a longer discussion of this from a "Complex Systems" point of view
Note the simple N-body problem has some interesting features
  • Very low communication/compute ratios
  • Best parallel methods violate owner computes rule -- also true in recent molecular dynamics problems with shorter range force
  • Unexpected dimension



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