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xctheo/RATE.js

Forked from ghalimi/RATE.js
Created December 1, 2016 21:45
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  1. @ghalimi ghalimi revised this gist Jan 26, 2013. 1 changed file with 3 additions and 0 deletions.
    3 changes: 3 additions & 0 deletions RATE.js
    View file
    Original file line number Diff line number Diff line change
    @@ -12,6 +12,9 @@ function RATE(periods, payment, present, future, type, guess) {
    // Initialize type
    var type = (typeof type === 'undefined') ? 0 : type;

    // Evaluate periods (TODO: replace with secure expression evaluator)
    periods = eval(periods);

    // Set maximum epsilon for end of iteration
    var epsMax = 1e-10;

  2. @ghalimi ghalimi created this gist Jan 25, 2013.
    49 changes: 49 additions & 0 deletions RATE.js
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    Original file line number Diff line number Diff line change
    @@ -0,0 +1,49 @@
    // Copyright (c) 2012 Sutoiku, Inc. (MIT License)

    function RATE(periods, payment, present, future, type, guess) {
    // Credits: rabugento

    // Initialize guess
    var guess = (typeof guess === 'undefined') ? 0.01 : guess;

    // Initialize future
    var future = (typeof future === 'undefined') ? 0 : future;

    // Initialize type
    var type = (typeof type === 'undefined') ? 0 : type;

    // Set maximum epsilon for end of iteration
    var epsMax = 1e-10;

    // Set maximum number of iterations
    var iterMax = 50;

    // Implement Newton's method
    var y, y0, y1, x0, x1 = 0, f = 0, i = 0;
    var rate = guess;
    if (Math.abs(rate) < epsMax) {
    y = present * (1 + nper * rate) + payment * (1 + rate * type) * nper + future;
    } else {
    f = Math.exp(nper * Math.log(1 + rate));
    y = present * f + payment * (1 / rate + type) * (f - 1) + future;
    }
    y0 = present + payment * nper + future;
    y1 = present * f + payment * (1 / rate + type) * (f - 1) + future;
    i = x0 = 0;
    x1 = rate;
    while ((Math.abs(y0 - y1) > epsMax) && (i < iterMax)) {
    rate = (y1 * x0 - y0 * x1) / (y1 - y0);
    x0 = x1;
    x1 = rate;
    if (Math.abs(rate) < epsMax) {
    y = present * (1 + nper * rate) + payment * (1 + rate * type) * nper + future;
    } else {
    f = Math.exp(nper * Math.log(1 + rate));
    y = present * f + payment * (1 / rate + type) * (f - 1) + future;
    }
    y0 = y1;
    y1 = y;
    ++i;
    }
    return rate;
    }