def monthlyPayment(principal, year_rate, year_duration):monthly_rate = year_rate / (12 * 100)   # convert 4.9 to 0.049 and  monthly interest ratemonth_amounts =  year_duration * 12# 每月月供monthly_payment = (principal * monthly_rate * (1 + monthly_rate) ** month_amounts) / ((1 + monthly_rate) ** month_amounts - 1)#总利息total_interest_payable = monthly_payment * month_amounts - principalprint('-----------------------------------')print ('Total interest payable is %.2f ' % total_interest_payable)for i in range (1, month_amounts + 1):#每月应还利息monthly_interest_payable = principal * monthly_rate * ((1 + monthly_rate) ** month_amounts - (1 + monthly_rate) ** (i - 1 ))/ ((1 + monthly_rate) ** month_amounts -1)#每月应还本金monthly_principal_payable = principal * monthly_rate * (1 + monthly_rate) ** (i - 1)/ ((1 + monthly_rate) ** month_amounts -1)#每月利息占比monthly_interest_percentage = monthly_interest_payable * 100 / monthly_paymentprint('-----------------------------------')print ('%dth monthly payment is : %.2f (Interest: %.2f and Principal: %.2f)' % (i, monthly_payment,monthly_interest_payable,monthly_principal_payable))print('%dth month interest percentage is %.2f %%' % (i,monthly_interest_percentage))returnif __name__ == '__main__':principal = int(input('Please input your loan amounts:'))year_rate = float(input('Please input Year Debt Interest Rate:(such as 4.9,it means 4.9%)'))year_duration = int(input('Please input Debt Year Duration:'))monthlyPayment(principal, year_rate, year_duration)