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- c*************************************************************************
- c GETACCH_A3.F
- c*************************************************************************
- c This subroutine calculates the 3rd term acceleration on the massive particles
- c in the HELIOCENTRIC frame. This term is the direct cross terms
- c Input:
- c nbod ==> number of massive bodies (int scalor)
- c mass ==> mass of bodies (real array)
- c xh,yh,zh ==> position in heliocentric coord
- c (real arrays)
- c Output:
- c axh3,ayh3,azh3 ==> 3rd term of acceleration in helio coord
- c (real arrays)
- c
- c Author: Hal Levison
- c Date: 2/2/93
- c Last revision: 11/21/96
- subroutine getacch_ah3(nbod,mass,xh,yh,zh,axh3,ayh3,azh3)
- include '../../swift.inc'
- c... Inputs:
- integer nbod
- real*8 mass(nbod),xh(nbod),yh(nbod),zh(nbod)
- c... Outputs:
- real*8 axh3(nbod),ayh3(nbod),azh3(nbod)
- c... Internals:
- integer i,j
- real*8 dx,dy,dz,rji2,faci,facj,irij3
- c------
- c... Executable code
- do i=1,nbod
- axh3(i) = 0.0
- ayh3(i) = 0.0
- azh3(i) = 0.0
- enddo
- do i=2,nbod-1
- do j=i+1,nbod
- dx = xh(j) - xh(i)
- dy = yh(j) - yh(i)
- dz = zh(j) - zh(i)
- rji2 = dx*dx + dy*dy + dz*dz
- irij3 = 1.0d0/(rji2*sqrt(rji2))
- faci = mass(i)*irij3
- facj = mass(j)*irij3
- axh3(j) = axh3(j) - faci*dx
- ayh3(j) = ayh3(j) - faci*dy
- azh3(j) = azh3(j) - faci*dz
- axh3(i) = axh3(i) + facj*dx
- ayh3(i) = ayh3(i) + facj*dy
- azh3(i) = azh3(i) + facj*dz
- enddo
- enddo
- return
- end ! getacch_ah3
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