抵押贷款计算器数学错误

Question

此程序运行正常，但每月付款 returns 完全关闭。对于 400,000 美元的本金、11% 的利率和 10 年的付款期，它 returns 每月支付 44000.16 美元。我用谷歌搜索了抵押贷款支付的等式（算法？）并将其输入，但不确定我哪里出错了。

import locale
locale.setlocale(locale.LC_ALL, '')

def mortgage(principal, interest, n):
    payment = principal*((interest*(1+interest)**n) / ((1+interest)**n-1))
    return payment

principal = float(input("What is the amount of the loan you are taking out? $"))
interest = float(input("What is the interest rate? (%) ")) / 100
n = float(input("How many years? ")) * 12
print
print "Your monthly payment would be", locale.currency(mortgage(principal, interest, n))

Answer 1

问题出在您使用的利率上。您要求的是年利率，从不转换为月利率。

来自https://en.wikipedia.org/wiki/Mortgage_calculator#Monthly_payment_formula：

r - the monthly interest rate, expressed as a decimal, not a percentage. Since the quoted yearly percentage rate is not a compounded rate, the monthly percentage rate is simply the yearly percentage rate divided by 12; dividing the monthly percentage rate by 100 gives r, the monthly rate expressed as a decimal.

我刚刚在我的电脑上试了一下，用利率除以 12 计算得出每月 5510 美元，这与其他抵押贷款计算器一致。

抵押贷款计算器数学错误

Mortgage calculator math error

python

math

calculator