PMT_js_func.js

function pmt(start, rate_as_percentage, num_periods, lifetime) {
    var rate_per_period = ((rate_as_percentage/100) / num_periods);
    // e.g. num_periods == 12 months, lifetimes = 4 years for 4 years, 12 months per year
    var total_periods = num_periods * lifetime;
    var p = (start * rate_per_period * Math.pow((1 + rate_per_period), total_periods)) / (Math.pow((1+rate_per_period), total_periods)-1);
    console.log(Math.pow((1 + rate_per_period), total_periods));
    return p;
}