無法得到此while while循環權（python）

Question

我正在創建一個程序，它將計算出信用卡支付的最低月度支付，並給定一定的信用卡餘額和利率。回報的時間框架是12個月，每月付款必須精確到最近的一分錢，使用二分搜索。

我能夠得到答案，問題是我無法讓我的while循環退出，一旦每月支付計算到最接近的分，所以我不得不做一個無限的while循環，有一個elif聲明在while循環的底部，爲我退出。我想知道是否有人可以找出給while循環的條件，所以它會自行退出。此外，我剛剛開始學習Python一週前，並希望得到一些關於我的代碼是好還是壞的建議。有任何想法嗎？

# random balance 
balance = 999999 
# random interest rate 
annualInterestRate = 0.18 
# assign balance to another variable that will undergo the testing 
balance_tested = balance 
# bounds of bisection search 
low = (balance/12.0) 
high = ((balance * (1 + (annualInterestRate/12.0))**12)/12.0) 
# start month 
month = 1 
monthlyPayment = (low + high)/2.0 #Averages out the bounds to meet in the middle 
while abs(balance_tested != 0): #While loop that I can't get right, just made it to run infinitely 
    balance_tested = balance #Resets balance being tested back to original balance 
    monthlyPayment = (low + high)/2.0 #Bisection search recalculates 
    month = 1 #Month reset back to 1 
    while month <= 12: #Loops through all 12 months with the payments being made and interested getting added 
     balance_tested = (balance_tested - monthlyPayment) 
     balance_tested += (balance_tested * (annualInterestRate/12)) 
     month += 1 
     print "Balance Remaining: %.20f" % balance_tested 
    if balance_tested < 0: #If the bisection search guesses to high, decreases the high bound 
     high = monthlyPayment 
    elif balance_tested <= 0.01: #Conditional statement that stops the testing if the balance gets paid off to the cent 
     break 
    else: #If bisection search guesses to low, increases low bound 
     low = monthlyPayment 
    print "Monthly Payment: %.2f" % monthlyPayment 

print "Lowest Payment: %.2f" % monthlyPayment 

Answer 1

是否有任何理由使用break語句而不是僅僅將它作爲while循環的條件？

balance = 999999 
annualInterestRate = 0.18 
balance_tested = balance 
low = (balance/12.0) #Lower bound of bisection search 
high = ((balance * (1 + (annualInterestRate/12.0))**12)/12.0) 
month = 1 
monthlyPayment = (low + high)/2.0 
while not (balance_tested <= 0.01): 
    balance_tested = balance 
    monthlyPayment = (low + high)/2.0 
    month = 1 
    while month <= 12: 
     balance_tested = (balance_tested - monthlyPayment) 
     balance_tested += (balance_tested * (annualInterestRate/12)) 
     month += 1 
     print "Balance Remaining: %.20f" % balance_tested 
    if balance_tested < 0: 
     high = monthlyPayment 
    else: 
     low = monthlyPayment 
    print "Monthly Payment: %.2f" % monthlyPayment 

print "Lowest Payment: %.2f" % monthlyPayment 

Answer 2

你已經有了條件，爲什麼不把是對於while語句呢？

while not balance_tested <= 0.01: 
    # etc. 

Answer 3

while abs(balance_tested != 0): 

會留在循環，如果balance_tested變爲負值。做這個

while balance_tested >= 0.1: 

這將自動處理舍入時，它跌到一分錢以下。