等額本息,是指一種貸款的還款方式。等額本息是在還款期內,每月償還同等數額的貸款(包括本金和利息)。
計算公式
每月還款額=[貸款本金×月利率×(1+月利率)^還款月數]÷[(1+月利率)^還款月數-1]
還款公式推導
設貸款總額爲M,銀行月利率爲p,總期數爲n(個月),月還款額爲x,則各個月所欠銀行貸款爲:
a[n] =(1 + p)*a[n - 1] - x ;其中a[0]=M
由於還款總期數爲n,也即第n月剛好還完銀行所有貸款,令a[n]=0,求x:
JAVA實現
import java.util.Scanner;
public class ComputeLoan {
public static void main(String[] args) {
// Create a Scanner
Scanner input = new Scanner(System.in);
// Enter yearly interest rate
System.out.print("Enter yearly interest rate, for example 8.25: ");
double annualInterestRate = input.nextDouble();
// Obtain monthly interest rate
double monthlyInterestRate = annualInterestRate / 1200;
// Enter number of years
System.out.print(
"Enter number of years as an integer, for example 5: ");
int numberOfYears = input.nextInt();
// Enter loan amount
System.out.print("Enter loan amount, for example 120000.95: ");
double loanAmount = input.nextDouble();
// Calculate payment
double monthlyPayment = loanAmount * monthlyInterestRate / (1
- 1 / Math.pow(1 + monthlyInterestRate, numberOfYears * 12));
double totalPayment = monthlyPayment * numberOfYears * 12;
// Display results
System.out.println("The monthly payment is $" +
(int)(monthlyPayment * 100) / 100.0);
System.out.println("The total payment is $" +
(int)(totalPayment * 100) / 100.0);
}
}
run:
Enter yearly interest rate, for example 8.25: 5.5
Enter number of years as an integer, for example 5: 20
Enter loan amount, for example 120000.95: 500000
The monthly payment is $3439.43
The total payment is $825464.76
成功構建 (總時間: 49 秒)