我試圖運行一些計算以表示特定的價格(即20.30)。如何在浮點計算中控制小數位數?
我已經嘗試了Float#round方法,但是包含這些值的實例變量最終會在幾次計算後開始表示看起來像24.43418的數字。
這僅僅是我創建把一個用戶輸入一個百分比
class Fixnum
def percentage
self.to_f/100
end
end
的@bankroll_amount和@risk_amount值應計算到兩位小數點
class Client
def initialize(bankroll, unit)
@bankroll_amount = bankroll.to_i.round(2)
@unit_percentage = unit.to_i.percentage
default_risk_amount.round(2)
evaluate_default_unit!.round(2)
end
def default_risk_amount
@risk_amount = @unit_percentage * @bankroll_amount
@risk_amount.round(2)
end
# simulates what an updated bankroll looks like after a win based on clients "unit" amount
def risk_win
@bankroll_amount = @bankroll_amount + @risk_amount
@bankroll_amount.round(2)
evaluate_default_unit!.round(2)
end
# simulates what a clients updated bankroll looks like after a loss based on clients "unit" amount
def risk_loss
@bankroll_amount = @bankroll_amount - @risk_amount
evaluate_default_unit!
end
def evaluate_default_unit!
@risk_amount = @unit_percentage * @bankroll_amount.round(2)
end
end
林不知道的方法如果這與我初始化這些實例變量有什麼關係,但是@risk_amount返回正確的兩個十進制值,但是當我返回對象時,裏面的實例變量已經運行了小數。
c = Client.new 2000, 1
<Client:0x000001018956a0 @bankroll_amount=2000.0, @unit_percentage=0.01, @risk_amount=20.0>
c.risk_win
=> 20.2
當我運行c.risk_win的是,它最終會返回
c
<Client:0x000001018956a0 @bankroll_amount=2440.3802, @unit_percentage=0.01, @risk_amount=24.4038>