Javascript中的PMT功能

Question

我想在Javascript中使用Excel PMT功能。参数是

Pmt（interest_rate，number_payments，PV，FV，Type）

interest_rate : the interest rate for the loan.
number_payments : the number of payments for the loan.
PV : the present value or principal of the loan.
FV : It is the future value or the loan amount outstanding after all payments have been made. 

Type is : It indicates when the payments are due. Type can be one of the following values:
 0, 1

你可以参考：http://www.techonthenet.com/excel/formulas/pmt.php

这是我使用的代码，我被困在最后一个参数中。这是“类型是”0或1.请如何影响计算。

function PMT (ir, np, pv, fv ) {
 /*
 ir - interest rate per month
 np - number of periods (months)
 pv - present value
 fv - future value (residual value)
 */
 pmt = ( ir * ( pv * Math.pow ( (ir+1), np ) + fv ) ) / ( ( ir + 1 ) * ( Math.pow ( (ir+1), np) -1 ) );
 return pmt;
}

我需要它在普通的js而不是jquery pls。提前致谢

Answer 1

理解Type参数影响的最简单方法是尝试以下值：年利率= 12％，月数= 1，当前值= 100

当Type = 0（默认值）时，PMT（）函数将产生101

当Type = 1时，PMT（）函数将产生100

当Type = 0时，利息计算为1个月，因为假定付款是在月末。对于Type = 1，利息计算为0个月，因为付款是在月初。

Answer 2

一些谷歌搜索后，这是我的PMT功能版本：

function PMT(ir, np, pv, fv, type) {
    /*
     * ir   - interest rate per month
     * np   - number of periods (months)
     * pv   - present value
     * fv   - future value
     * type - when the payments are due:
     *        0: end of the period, e.g. end of month (default)
     *        1: beginning of period
     */
    var pmt, pvif;

    fv || (fv = 0);
    type || (type = 0);

    if (ir === 0)
        return -(pv + fv)/np;

    pvif = Math.pow(1 + ir, np);
    pmt = - ir * pv * (pvif + fv) / (pvif - 1);

    if (type === 1)
        pmt /= (1 + ir);

    return pmt;
}

示例15年内以每年7.5％的利率偿还20万美元贷款所需的每月付款是多少？

ir = 0.075 / 12
np = 15 * 12
pv = 200000
pmt = PMT(ir, np, pv).toFixed(2) = -1854.02
payoff = pmt * np = -333723.6

Answer 3

这是我的PMT版本

PMT: function(rate, nperiod, pv, fv, type) {
    if (!fv) fv = 0;
    if (!type) type = 0;

    if (rate == 0) return -(pv + fv)/nperiod;

    var pvif = Math.pow(1 + rate, nperiod);
    var pmt = rate / (pvif - 1) * -(pv * pvif + fv);

    if (type == 1) {
        pmt /= (1 + rate);
    };

    return pmt;
},

////打电话给PMT

 var result = PMT(6.5/1200 , 30*12 , 65000 , 0 , 0);
 console.log(result);
 //// result : -410.8442152704279

///其他以及IPMT和PPMT

 IPMT: function(pv, pmt, rate, per) {
    var tmp = Math.pow(1 + rate, per);
    return 0 - (pv * tmp * rate + pmt * (tmp - 1));
},

PPMT: function(rate, per, nper, pv, fv, type) {
    if (per < 1 || (per >= nper + 1)) return null;
    var pmt = this.PMT(rate, nper, pv, fv, type);
    var ipmt = this.IPMT(pv, pmt, rate, per - 1);
    return pmt - ipmt;
},

Answer 4

我使用以下功能解决了这个问题，感谢网站tvmcalcs.com，预付款示例。

function pmt(monthlyRate, monthlyPayments, presentValue, residualValue, advancedPayments) {
        t1 = 1+monthlyRate
        t2 = Math.pow(t1,monthlyPayments)
        t3 = Math.pow(t1,(monthlyPayments-advancedPayments))
        return (presentValue-(residualValue/t2))/(((1-(1/(t3)))/monthlyRate)+advancedPayments);
    }

或者如果你有，就像我们的情况一样，是年度报价

function pmtWithAnnualRate(annualRate, monthlyPayments, presentValue, residualValue, advancedPayments) {
    monthlyRate = annualRate / 1200
    t1 = 1 + monthlyRate
    t2 = Math.pow(t1,monthlyPayments)
    t3 = Math.pow(t1,(monthlyPayments-advancedPayments))
    return (presentValue-(residualValue/t2))/(((1-(1/(t3)))/monthlyRate)+advancedPayments);
}