hotsys.f

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      SUBROUTINE hotsys
*
*
*       Hot initial system.
*       -------------------
*
      include 'common6.h'
*
*
*       Determine the rms velocity from current kinetic energy.
      vrms = 0.0
      DO 10 i = 1,n
          DO 5 k = 1,3
              vrms = vrms + body(i)*xdot(k,i)**2
    5     CONTINUE
   10 CONTINUE
      vrms = sqrt(vrms/zmass)
*
*       Define GM & PC in cgs units and form velocity scale in km/sec.
      gm = 6.67e-08*1.989e+33
      pc = 3.0857e+18
      vstar = 1.0e-05*sqrt(gm/pc)
*
*       Ensure ZMBAR & RBAR > 0 (=0: assume <M>/Sun = 1, RBAR = 1 pc).
      IF (zmbar.LE.0.0d0) zmbar = float(n)/zmass
      IF (rbar.LE.0.0d0) rbar = 1.0
*
*       Scale to working units of RBAR in pc & ZMBAR in solar masses.
      vstar = vstar*sqrt(zmass*zmbar/rbar)
*
*       Read central velocity dispersion and form scaling factor.
      READ (5,*)  sigma0
      vscale = sigma0/(vstar*vrms)
*
*       Scale the velocities to central velocity dispersion of SIGMA0 km/sec.
      DO 20 i = 1,n
          DO 15 k = 1,3
              xdot(k,i) = vscale*xdot(k,i)
              x0dot(k,i) = xdot(k,i)
   15     CONTINUE
   20 CONTINUE
*
*       Rescale crossing time, output times & termination time.
      ratio = sigma0/vstar
      tcr = tcr/ratio
      tcr0 = tcr
      dtadj = dtadj/ratio
      deltat = deltat/ratio
      tcrit = tcrit/ratio
      vc = vscale*vc
*
      WRITE (6,30)  sigma0, vrms, vscale
   30 FORMAT (/,12x,'HOT SYSTEM:   SIGMA0 =',f5.1,'  <V> =',f6.3,
     &                                              '  VSCALE =',f6.3,/)
*
      RETURN
*
      END