模拟Excel的Javascript Yield Calculator

Question

我正在构建一个债券计算器，我需要以我使用Excel作为指南和=YIELD()函数的百分比来输出收益率。

在这些给定值的excel中，我返回5.181800

=YIELD(19-02-2015, 21-02-2019, 5.75/100, 102.031, 100, 2, 1)*100
=YIELD(SettlementDate, MaturityDate, CouponsRate, BondPrice, 100, Coupons PA, Basis) * 100

在Javascript中我写过

function dayDiff(date1, date2) {

    var timeDiff = Math.abs(date2.getTime() - date1.getTime());
    var diffDays = Math.ceil(timeDiff / (1000 * 3600 * 24)); 

    return diffDays;
}

var settlement = '2015-02-19',
maturity = '2019-02-21',

settlement = new Date(settlement);
maturity = new Date(maturity);

var timeToMaturity = dayDiff(settlement, maturity);
var coupon = 5.75 / 100;
var yield = 102.031;
var redemption = 100;
var frequency = 2;

var price = 0.0;
if(timeToMaturity > 0) {
    price += redemption;
}
var paymentTime = timeToMaturity;
while(paymentTime > 0) {
    price += coupon/frequency;

    // Discount back
    price = price / (1.0 + yield / frequency);
    paymentTime -= 1.0 / frequency;
}
var accrualPeriod = 0.0-paymentTime;
price *= Math.pow(1.0 + yield / frequency, accrualPeriod*frequency);
price -= coupon/frequency * accrualPeriod*frequency;

console.log(price * 100 * 100);

这会返回5.635542139153786任何人都可以告诉我哪里出错了吗？