A linear congruential generator (LCG) is an algorithm that yields a sequence of pseudo-randomized numbers calculated with a discontinuous piecewise linear equation.

linear-congruential-generator.js

/**
 * Linear Congruential Generator
 * http://en.wikipedia.org/wiki/Linear_congruential_generator
 */


function RandomNumberGeneratorFn($log) {
    'use strict';
    
    $log = $log || console;
    function RandomNumberGenerator() {

    }

    RandomNumberGenerator.A = 0x5DEECE66D;
    RandomNumberGenerator.C = 0xB;
    /*jshint bitwise:false */
    RandomNumberGenerator.RANGE = 1 << 49;
    RandomNumberGenerator.r = 1;

    RandomNumberGenerator.setSeed = function (seed) {
        if (isNaN(seed)) {
            throw new Error('seed [' + seed + '] not valid');
            //return false; // unreachable
        }
        var num = parseInt(seed);
        RandomNumberGenerator.r = num;
        $log.debug('seed: ' + seed);
        return true;
    };

    RandomNumberGenerator.random = function () {
        RandomNumberGenerator.r =
            (((RandomNumberGenerator.A * RandomNumberGenerator.r) +
            RandomNumberGenerator.C) % RandomNumberGenerator.RANGE);
        /*jshint bitwise:false */
        return RandomNumberGenerator.r >> 3;
    };

    RandomNumberGenerator.integer = function (min, max) {
        var returnValue = parseInt(min) + parseInt(RandomNumberGenerator.random() % (max - min + 1));
        //$log.debug('min: ' + min   + ':: max: ' + max+ ':: return: ' + returnValue);
        return returnValue;
    };

    RandomNumberGenerator.float = function (min, max, decimal) {
        if (!decimal) {
            decimal = 2;
        }
        var multiplier = (10 * decimal);
        var integerValue = RandomNumberGenerator.integer(min * multiplier, max * multiplier);
        var returnValue = integerValue / multiplier;
        $log.debug('min: ' + min + ':: max: ' + max + ':: return: ' + returnValue);
        return returnValue;
    };


    RandomNumberGenerator.randomNumber = function () {
        /*jshint bitwise:false */
        return RandomNumberGenerator.random() / (RandomNumberGenerator.RANGE >> 3);
    };

    return RandomNumberGenerator;
}