IRR

calculate = (valid = true) ->

  # процент первого взноса от стоимости
  calc_out.paid_pct = Math.round(100 * calc_in.paid / calc_in.total) + '%'

  # подключаем библиотеку
  calFinance = new Finance()

  if calc_in.increase != null

    # стоимость юнита минус предоплата
    principal = calc_in.total - calc_in.paid

    per_month = - Math.round( pmt(0.01 * calc_in.rate, calc_in.time, principal) / 12 )
    per_month_profit = calc_in.rent - per_month
    calc_out.price = Math.round( calc_in.total * Math.pow((1 + calc_in.increase * 0.01), 10) )

    # calc_out.profit = Math.round( rate(calc_in.time * 12, per_month_profit, - calc_in.paid, calc_out.price) * 1200 )
    # calc_out.profit = Math.round( rate(calc_in.time, per_month_profit * 12, - calc_in.paid, calc_out.price) * 100 )

    if valid == true

      # Получаем ежегодный платеж.
      need_pay_per_year =  calFinance.AM(principal, calc_in.rate, calc_in.time, 0) * 12;

      # Теперь делаем введенную сумму аренды минус ежегодный платеж = чистый ежегодный платеж (ЧЕП).
      clear_plus_per_year = ( calc_in.rent * 12 ) - need_pay_per_year;

      profit = calFinance.IRR(-calc_in.paid, clear_plus_per_year, clear_plus_per_year, clear_plus_per_year, clear_plus_per_year, clear_plus_per_year, clear_plus_per_year, clear_plus_per_year, clear_plus_per_year, clear_plus_per_year, clear_plus_per_year +  calc_out.price)