Scripted HTML version of Foils prepared 12 November 1996

Foil 13 Grav Pipeline Algorithm, concluded

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 123.8
if (( N mod 2) = 0 ) then ! final one way acceleration if N even
  • Xc = cshift (Xc, dim=2, shift = -1)
  • Mc = cshift (Mc, dim=2, shift = -1)
  • Ac = cshift (Ac, dim=2, shift = -1)
  • D = Xc-X
  • R = sqrt (spread (sum (D*D, dim=1), dim=1, ncopies=3)))
  • D = D/R**3
  • A = A + Mc*D
end if
! combine accelerations for final result - circulating particle in i'th
! position corresponds to fixed particle (i-(N-1)/2)
Grav = A + cshift (Ac, dim=2, shift = (N-1)/2)
end function Grav

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