HTML version of Scripted Foils prepared 12 November 1996

Foil 6 Some Inefficiencies of the N2 Algorithm - II

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 115.2
1 Also, all particle information is sent to all processors, taking O(N2) space whereas natural algorithms use O(N) space and this is how special purpose machines like GRAPE get their cost effectiveness
  • If N is one million as for globular cluster problem, there is a big difference between DRAM cost of 106 and 1012 units of memory
2 Space is further wasted as everything is spread to 3 dimensional arrays even when arrays like mass are naturally one dimensional!
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