rpmax2.f

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      REAL*8 FUNCTION rpmax2(R1,R2,M1,M2,KS1,KS2,VINF)
*
*
*       Maximum periastron factor for capture.
*       --------------------------------------
*
*       Developed by Rosemary Mardling (March 1996).
*       @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
*
      REAL*8  r1,r2,m1,m2,vinf,m21,a(8),b(2),p(2)
      INTEGER ks1,ks2,ks(2)
      DATA  a /-600.2227,3538.748,1703.075,77.31540,
     &         191.8260,-2.203482,1202.116,70.80281/
      DATA b /0.54,1.08/
*
*
*       Define mass and radius ratios and swap stellar type if necessary.
      IF (r1.GE.r2) THEN
          m21 = m2/m1
          r21 = r2/r1
          ks(1) = ks1
      ks(2) = ks2
      ELSE
      m21 = m1/m2
      r21 = r1/r2
      ks(1) = ks2
      ks(2) = ks1
      END IF
*
*       Choose polytropic index for each star (adopt n=1.5 for giants).
      DO 1 i = 1,2
          IF(ks(i).EQ.0.OR.ks(i).EQ.3.OR.ks(i).EQ.5.OR.
     &       ks(i).EQ.6.OR.ks(i).EQ.9)THEN
              ip = 1
              pp = b(1)
          ELSE
              ip = 5
              pp = b(2)
          ENDIF
          p(i) = (((a(ip+3)*m21 + a(ip+2))*m21 + a(ip+1))*m21 
     &                                         + a(ip))/vinf**pp
    1 CONTINUE
*
*       Calculate maximum periastron separation for capture (note arg < 0).
      z = p(1) + (r21**5/m21**2)*p(2)
      IF (z.LE.0.0) THEN
*       Adopt factor 2 for collision test in case of small mass ratio.
          rpmax2 = 2.0
      ELSE
          rpmax2 = z**(1.0/6.0)
*         RPMAX2 = (P(1) + (R21**5/M21**2)*P(2))**(1.0/6.0)
      END IF
*
      RETURN
*
      END