我目前正在通过YouTube上的视频教程学习Python,并遇到一个公式似乎无法理解,因为对我来说看起来都不对。练习的基本概念是创建一个抵押贷款计算器,要求用户输入三个信息:贷款金额、利率和贷款期限(年)。
然后它会为用户计算每月付款额。下面是我的代码:
__author__ = 'Rick'
# This program calculates monthly repayments on an interest rate loan/mortgage.
loanAmount = input("How much do you want to borrow? \n")
interestRate = input("What is the interest rate on your loan? \n")
repaymentLength = input("How many years to repay your loan? \n")
#converting the string input variables to float
loanAmount = float(loanAmount)
interestRate = float(interestRate)
repaymentLength = float(repaymentLength)
#working out the interest rate to a decimal number
interestCalculation = interestRate / 100
print(interestRate)
print(interestCalculation)
#working out the number of payments over the course of the loan period.
numberOfPayments = repaymentLength*12
#Formula
#M = L[i(1+i)n] / [(1+i)n-1]
# * M = Monthly Payment (what were trying to find out)
# * L = Loan Amount (loanAmount)
# * I = Interest Rate (for an interest rate of 5%, i = 0.05 (interestCalculation)
# * N = Number of Payments (repaymentLength)
monthlyRepaymentCost = loanAmount * interestCalculation * (1+interestCalculation) * numberOfPayments / ((1+interestCalculation) * numberOfPayments - 1)
#THIS IS FROM ANOTHER BIT OF CODE THAT IS SUPPOSE TO BE RIGHT BUT ISNT---
# repaymentCost = loanAmount * interestRate * (1+ interestRate) * numberOfPayments / ((1 + interestRate) * numberOfPayments -1)
#working out the total cost of the repayment over the full term of the loan
totalCharge = (monthlyRepaymentCost * numberOfPayments) - loanAmount
print("You want to borrow £" + str(loanAmount) + " over " + str(repaymentLength) + " years, with an interest rate of " + str(interestRate) + "%!")
print("Your monthly repayment will be £" + str(monthlyRepaymentCost))
print("Your monthly repayment will be £%.2f " % monthlyRepaymentCost)
print("The total charge on this loan will be £%.2f !" % totalCharge)
所有东西都工作正常,但最后抛出的价值完全错误...一笔年利率为10%,金额为£100的贷款在1年内不应该让我每月支付£0.83。如果有帮助理解这个方程式的任何帮助,将不胜感激。
monthly_rate = (1 + annual_rate)**(1/12.) - 1
的东西。 - Mark Dickinson