Basic HTML version of Foils prepared 14 October 1997

Foil 33 The Grav Function in Data Parallel Algorithm - II

From Fox Presentation Fall 1995 CPS615 Basic Simulation Track for Computational Science -- Fall Semester 95/96/97. by Nancy McCracken and Geoffrey C. Fox
! set up arrays of particles Xi and particles Xj
  • Xi = spread (X, dim =3, ncopies = N )
  • Xj = spread (X, dim = 2, ncopies = N )
  • Ms = spread (M, dim=2, ncopies = N )
! displacements and Euclidean distance
  • D = Xj - Xi
  • R = sqrt (spread ( sum ( D*D, dim=1), dim =1, ncopies=3)))
! calculate accelerations for all pairs except on main diagonal
  • where (diag)
    • A=0.0
  • elsewhere
    • A=G*Ms*D / R**3
  • end where
  • Grav = sum (A, dim=3)
end function Grav

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