Class: Bankroll::InterestRate

Inherits:
Object
  • Object
show all
Extended by:
Callable, Dry::Initializer
Defined in:
lib/bankroll/interest_rate.rb

Instance Method Summary collapse

Instance Method Details

#call(guess = 0.1) ⇒ Object 



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# File 'lib/bankroll/interest_rate.rb', line 16

def call(guess = 0.1)
  significance_required = 1e-6
  stop = false

  next_guess = 0

  loop do
    temp = newton_iteration(
      guess,
      @periods,
      @payment,
      @present_value,
      @future_value,
      0
    )
    next_guess = (guess - temp).round(20)
    difference = (next_guess - guess).abs
    stop = difference < significance_required
    guess = next_guess
    break if stop
  end

  next_guess
end