fclose.f

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      SUBROUTINE fclose(I,NNB)
*
*
*       Force & first derivative from close bodies.
*       -------------------------------------------
*
      include 'common6.h'
      REAL*8  a(9)
*
*
*       Initialize F & FDOT for body #I.
      DO 10 k = 1,3
          f(k,i) = 0.0d0
          fdot(k,i) = 0.0d0
   10 CONTINUE
*
*       Obtain F & FDOT due to NNB members of JLIST.
      DO 50 l = 1,nnb
          j = jlist(l)
          IF (j.EQ.i) go to 50
*
          rij2 = 0.0d0
          rijdot = 0.0d0
          DO 20 k = 1,3
              a(k) = x(k,j) - x(k,i)
              a(k+3) = xdot(k,j) - xdot(k,i)
              rij2 = rij2 + a(k)**2
              rijdot = rijdot + a(k)*a(k+3)
   20     CONTINUE
          a(8) = body(j)/(rij2*sqrt(rij2))
          a(9) = 3.0*rijdot/rij2
*
*       Set approximate F & FDOT to be used by body #I in FPOLY2.
          DO 30 k = 1,3
              f(k,i) = f(k,i) + a(k)*a(8)
              fdot(k,i) = fdot(k,i) + (a(k+3) - a(k)*a(9))*a(8)
   30     CONTINUE
   50 CONTINUE
*
*       Initialize time of last force (prevents prediction in FPOLY2).
      t0(i) = time
*
      RETURN
*
      END