Basic HTML version of Foils prepared 22 February 1998

Foil 50 N-body Problem is a one dimensional Algorithm

From Fox Presentation Fall 1995 CPS615 Basic Simulation Track for Computational Science -- 1998 Enhancements. by Geoffrey C. Fox


1 Not only is performance model characteristic of one dimensional problem but we also we used a one-dimension parallel decomposition
2 Note these one dimensional characteristics are independent of dimension of space that particles move in.
3 Normally d is thought of as dimension of physical space in which problem posed.
4 But the geometrical interpretation of d is only valid where interaction between particles is itself geometrical i.e. short range
5 Rather N body algorithm has no geometric structure and you see d=1 characteristic of algorithm
6 See Chapter 3 of Parallel Computing Works for a longer discussion of this from a "Complex Systems" point of view
7 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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