as3/javascript贷款公式从周利率计算原理

as3/javascript loan formula to calculate principle from weekly rate

本文关键字：周利率 计算 javascript as3      更新时间：2023-09-26

我有一个AS3函数来计算每周还款值，前提是我有贷款金额、利率和；任期以年为单位。

private function calculateRepayment(_loanAmount, _years, _interest):Number
{
    var nWeek = _years * 52;
    var nInterest = _interest/(52*100);
    var nRepayment = ( _loanAmount * nInterest *Math.pow((1+nInterest),nWeek) ) / ( Math.pow((1+nInterest),nWeek)-1 );
    return Number(nRepayment);
}

现在我需要编写一个函数，根据每周还款、利率和利率的值来计算贷款金额；任期以年为单位

任何关于转换为AS3或javascript的公式的帮助都将非常感谢，我认为理论上它是loanAmount=利息/利率时间。

例如：

private function calculateLoanAmount(_repaymentAmount, _years, _interest):Number
{
    // var nLoanAmount:Number = ????
    return Number(nLoanAmount);
}

好吧，我算出了，这是函数：

private function calculateLoanAmount(_repayment, _years, _interest):Number
{
    var p:Number = _repayment; // weekly payment
    var i:Number = (_interest / 52) * 0.01; // weekly interest factor
    var n:Number = _years * 52; // number of weekly payments - (5 years) 5*52 = 260
    var principal:Number = (p * (1 - 1 / (Math.pow(1 + i, n)))) / i;
    principal = Math.round(roundDec(principal, 0)); // prepare for output
    return Number(principal);
}
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