# File ms6body.rb, line 133
  def ms6(dt)
    if @nsteps == 0
      @ap5 = acc
      yo6(dt)
    elsif @nsteps == 1
      @ap4 = acc
      yo6(dt)
    elsif @nsteps == 2
      @ap3 = acc
      yo6(dt)
    elsif @nsteps == 3
      @ap2 = acc
      yo6(dt)
    elsif @nsteps == 4
      @ap1 = acc
      yo6(dt)
    else
      ap0 = acc
      jdt = (ap0*137 - @ap1*300 + @ap2*300 - @ap3*200 + @ap4*75 - @ap5*12)/60
      sdt2 = (ap0*45 - @ap1*154 + @ap2*214 - @ap3*156 + @ap4*61 - @ap5*10)/12
      cdt3 = (ap0*17 - @ap1*71 + @ap2*118 - @ap3*98 + @ap4*41 - @ap5*7)/4
      pdt4 = ap0*3 - @ap1*14 + @ap2*26 - @ap3*24 + @ap4*11 - @ap5*2
      xdt5 = ap0 - @ap1*5 + @ap2*10 - @ap3*10 + @ap4*5 - @ap5
      @pos += (vel+(ap0+ (jdt+(sdt2+(cdt3+pdt4/6)/5)/4)/3)*dt/2)*dt
      @vel += (ap0+(jdt+(sdt2+(cdt3+(pdt4+xdt5/6)/5)/4)/3)/2)*dt
      @ap5 = @ap4
      @ap4 = @ap3
      @ap3 = @ap2
      @ap2 = @ap1
      @ap1 = ap0
    end
  end