expand2.f

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      SUBROUTINE expand2(IPAIR,SEMI0)
*
*
*       Expansion (contraction) of KS orbit.
*       ------------------------------------
*
      include 'common6.h'
*
*
*       Evaluate square regularized velocity.
      v20 = 0.0
      DO 10 k = 1,4
          v20 = v20 + udot(k,ipair)**2
   10 CONTINUE
*
*       Form KS coordinate & velocity scaling factors (general point is OK).
      i = n + ipair
      semi = -0.5d0*body(i)/h(ipair)
      c2 = sqrt(semi/semi0)
      v2 = 0.5*(body(i) + h(ipair)*r(ipair)*(semi/semi0))
      c1 = sqrt(v2/v20)
*
*       Re-scale KS variables to new energy (H < 0: constant eccentricity).
      r(ipair) = 0.0d0
      DO 20 k = 1,4
          u(k,ipair) = c2*u(k,ipair)
          udot(k,ipair) = c1*udot(k,ipair)
          u0(k,ipair) = u(k,ipair)
          r(ipair) = r(ipair) + u(k,ipair)**2
   20 CONTINUE
*
      RETURN
*
      END