# File ms8body.rb, line 133
  def ms6(dt)
    if @nsteps == 0
      @a5 = acc
      yo6(dt)
    elsif @nsteps == 1
      @a4 = acc
      yo6(dt)
    elsif @nsteps == 2
      @a3 = acc
      yo6(dt)
    elsif @nsteps == 3
      @a2 = acc
      yo6(dt)
    elsif @nsteps == 4
      @a1 = acc
      yo6(dt)
    else
      a0 = acc
      j = (a0*137 - @a1*300 + @a2*300 - @a3*200 + @a4*75 - @a5*12)/60
      s = (a0*45 - @a1*154 + @a2*214 - @a3*156 + @a4*61 - @a5*10)/12
      c = (a0*17 - @a1*71 + @a2*118 - @a3*98 + @a4*41 - @a5*7)/4
      p = a0*3 - @a1*14 + @a2*26 - @a3*24 + @a4*11 - @a5*2
      x = a0 - @a1*5 + @a2*10 - @a3*10 + @a4*5 - @a5
      @pos += (vel+(a0+(j+(s+(c+p/6)/5)/4)/3)*dt/2)*dt
      @vel += (a0 +(j +(s+(c+(p+x/6)/5)/4)/3)/2)*dt
      @a5 = @a4
      @a4 = @a3
      @a3 = @a2
      @a2 = @a1
      @a1 = a0
    end
  end