计算Java（TVM）的利率 [英] Calculate interest rate in Java (TVM)

问题描述

我一直在研究一个Java项目，它是计算器，可用于计算复合兴趣的不同场景（非常类似于图形计算器上的TVM函数，如这一个）

I've been working on a Java project which is calculator which can be used for calculating different scenarios of compound interest (very similar to the TVM Function found on a graphics calculator like this one)

计算器的主要功能是使用公式中的已知值计算缺失值。除了计算利率（ I ）

The main function of the calculator is to calculate missing values using the known values in a formula. I have gotten all of the formulas working except for the one which calculates Interest rate (I)

我已经做了一些研究，显然有没有直接的公式来计算利率。本网站： http://www.getobjects.com/Components/Finance/TVM/ formulas.html 显示了我需要使用的方法，但需要一些迭代才能使用反复试验找到 I 。 （查看链接，向下滚动到标题每年的利率）

I have done some research and apparently there is no straight formula to calculate the interest rate. This website: http://www.getobjects.com/Components/Finance/TVM/formulas.html shows the method i need to use, but it requires some iteration to find I using trial and error. (Check the link, Scroll down to the heading "Interest Rate Per Year")

这是我为它设置的结构：

Here is the structure I have set up for it:

public static double calculateI(double N, double PV, double PMT, double FV, double PY){
    //method for calculating I goes here

    return I;
}

我不知道如何实现这一点，有人可以建议一下这是怎么回事完成或指向正确的方向？

I am not sure how to implement this, could someone please suggest how this can be done or point me in the right direction?

提前致谢。

以下是@rocketboy建议后的代码

Here is my code after the suggestion made by @rocketboy

public static double formulaI(double ip, double N, double PV, double PMT, double FV, double PY){
    double I1=(PV*Math.pow((1+ip),N))+((PMT*1)*(Math.pow((1+ip),N))-1)+FV;
    return I1;
}
public static double calculateI(double N, double PV, double PMT, double FV, double PY){
    double ip=0;
    double res;
    do{
        res = formulaI(ip,N,PV,PMT,FV,PY);
        ip=ip+0.01;
        System.out.println(res);
    }while(res!=0);
    double I=ip*PY;
return I;
}

推荐答案

尝试类似：

double calculateI(/*all values for varialbles*/){
//definition;
}

Double.valueOf（d）.equals（0.0）;

Double.valueOf(d).equals(0.0);

long ip =0;
double res;

do{
   res = calculateI(ip, /*other constant values*/);
   ip++; /*Or you can increase ip according to your logic*/    
}while ( Double.valueOf(res).equals(0.0/*Expected result*/));

编辑：您必须处理边缘情况。等式可能永远不会收敛到0。

You have to handle the edge cases. The equation may not ever converge to 0.

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