Question

我正在尝试编写一个程序，该程序接受三个输入并通过以下等式表示：

futureInvestmentValue = investmentAmount * (1 + monthlyInterestRate)^(numberOfYears*12)

我正在使用的正确示例结果表明，对于investment amount = 1000.56，annual interest rate = 3.25（因此monthlyInterestRate = annual / 12）和numberOfYears = 1，我应该futureInvestmentValue = 1032.98

但是，我的程序声明了“$38045.96184617848”的最终结果（注意：我不需要回合）。

为什么会发生这种情况？

代码：

import java.util.Scanner;

public class num2_21 {

public static void main(String[] args) {

    System.out.println("This program was designed to calculate the future investment value of an investment. \n\n"
            + "When prompted, please enter the initial investment amount, interest APR (%), and length of investment (yrs). \n"
            + "Investment amount: ");
    Scanner in1 = new Scanner(System.in);
    double investAmount = in1.nextDouble();

    System.out.println("\n" + "Annual interest rate in percentage: ");
    Scanner in2 = new Scanner(System.in);
    double APR = in2.nextDouble();
    double monthlyInterest = APR / 12;

    System.out.println("\n" + "Length of investment: ");
    Scanner in3 = new Scanner(System.in);
    double investLength = in3.nextDouble();

    double futureInvestmentValue = investAmount * Math.pow((1 + monthlyInterest),(investLength*12));
    System.out.println("\n" + "Accumulated value: $" + futureInvestmentValue);


}

}

控制台：

This program was designed to calculate the future investment value of an investment. 

When prompted, please enter the initial investment amount, interest APR (%), and length of investment (yrs). 
Investment amount: 
1000.56

Annual interest rate in percentage: 
4.25

Length of investment: 
1

Accumulated value: $38045.96184617848

编辑：我忘记将APR除以100.我没有意识到我需要将其转换为小数。为疏忽道歉。我很欣赏额外的双眼。谢谢你的时间。

Answer 1

那么，这可能是因为425.0％的年利率不是太差，或者可能是因为你忘了除以100：

    double APR = in2.nextDouble() / 100.0;

包含Math.pow（）的公式产生意外结果

1 个答案: