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- ***********************************************************************
- * COORD_VH2VJ.F
- ***********************************************************************
- * PURPOSE: Converts from Heliocentric to Jacobi coords. VELOCITIES ONLY.
- * ARGUMENTS: Input is
- * nbod ==> number of objects (must be less than NBMAX)
- * (integer)
- * mass(*) ==> planetary masses (real array)
- * vxh(*),vyh(*),vzh(*) ==>barycentric particle velocities
- * (real array)
- * Returned are
- * vxj(*),vyj(*),vzj(*) ==> jacobi. particle velocities
- * (real array)
- *
- * ALGORITHM: See my notes Nov 21/92
- * REMARKS:
- *
- * AUTHOR: M. Duncan.
- * DATE WRITTEN: Jan 29, 1993.
- * REVISIONS: 2/20/2K HFL
- subroutine coord_vh2vj(nbod,mass,vxh,vyh,vzh,vxj,vyj,vzj)
- include '../swift.inc'
- c... Inputs:
- integer nbod
- real*8 mass(nbod)
- real*8 vxh(nbod),vyh(nbod),vzh(nbod)
- c... Outputs:
- real*8 vxj(nbod),vyj(nbod),vzj(nbod)
- c... Internals:
- real*8 eta(NTPMAX)
- real*8 sumvx,sumvy,sumvz
- real*8 capvx,capvy,capvz
- integer n
- c----
- c... Executable code
- c First calc. the array eta(*) then convert to jacobi velocities
- eta(1) = mass(1)
- do n = 2,nbod
- eta(n) = eta(n-1) + mass(n)
- enddo
- vxj(1) =0.d0
- vyj(1) =0.d0
- vzj(1) =0.d0
- vxj(2) = vxh(2)
- vyj(2) = vyh(2)
- vzj(2) = vzh(2)
- sumvx = mass(2)*vxh(2)
- sumvy = mass(2)*vyh(2)
- sumvz = mass(2)*vzh(2)
- capvx = sumvx/eta(2)
- capvy = sumvy/eta(2)
- capvz = sumvz/eta(2)
- do n=3,nbod
- vxj(n) = vxh(n) - capvx
- vyj(n) = vyh(n) - capvy
- vzj(n) = vzh(n) - capvz
- if(n.lt.nbod) then
- sumvx = sumvx + mass(n)*vxh(n)
- sumvy = sumvy + mass(n)*vyh(n)
- sumvz = sumvz + mass(n)*vzh(n)
- capvx =sumvx/eta(n)
- capvy =sumvy/eta(n)
- capvz =sumvz/eta(n)
- endif
- enddo
- 123 return
- end ! coord_vh2vj
- c--------------------------------------------------------------------------
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