javascript - 将数学公式转换为 JavaScript

Question

我需要帮助将贷款余额公式转换为 JavaScript 我已添加了公式图像

这就是我目前的情况，但我一直得到错误的答案。

 var loanBalance = a * Math.pow((1 + r), n) - p * ((Math.pow((1 + r), n) - 1) / r); 

我的计算器有四个函数，但只有这个给了我错误的答案，正如你所看到的，我对这一切都是新手，提前致谢。

这是我遇到问题的函数:

      function doBalance() {
        var principal = parseFloat(document.getElementById("borrowedBox").value);
        var annualRate = parseFloat(document.getElementById("rateBox").value);
        var years = parseFloat(document.getElementById("yearsBox").value);
        var periodsPerYear = parseFloat(document.getElementById("paymentBox").value);
        var numberOfPaymentsPaidToDate = parseFloat(document.getElementById("toDatePymtsBox").value);
        var result = 0;
        result = computeBalance(principal, annualRate, years, periodsPerYear, numberOfPaymentsPaidToDate);
        document.getElementById("outputDiv2").innerHTML = "$" + result;
    }

    function computeBalance(principal, annualRate, years, periodsPerYear, numberOfPaymentsPaidToDate) {
        var a = principal;
        var r = annualRate/periodsPerYear;
        var p = periodsPerYear*years;
        var n = numberOfPaymentsPaidToDate;
        var loanBalance = (a * (Math.pow((1 + r), n))) -( (p * (Math.pow((1 + r), n) - 1)) / r);
        return loanBalance.toFixed(2);
    }

答案应该是54306.40这些是我正在使用的值: Loan Calculator

Answer 1

拆分公式，

function loanBalancer(r,n,p,a){
  var powerfn = Math.pow((1+r), n);
  var firstprt = a * powerfn;
  var num = p(powerfn - 1);
  var den = r;
  return firstprt - (num/den) 
}