Typographic scale creator

scale.js

// 16 + 24 @ 1/2
// 15 + 20 @ 1/2
// 16 + 20 @ 1/2

scale = {
    main: 16,
    secondary: 20,
    fraction: 1/2,
    measurements: [],
    create: function(greater, lesser) {
        // default values for greater and lesser numbers amount
        greater = greater || 8;
        lesser = lesser || 2;
        // start subarrays with main and secondary numbers
        this.measurements = [[this.main], [this.secondary]];
        for (a = 0; a < 2; a++) {
            // make 8 (default) new greater numbers using inverse fraction
            for (b = 1; b < greater; b++) {
                this.measurements[a][b] = Math.round(this.measurements[a][b-1] * 1/this.fraction);
            }
            // make 2 (default) new lesser numbers using fraction
            for (c = 0; c < lesser; c++) {
                this.measurements[a].unshift(Math.round(this.measurements[a][0] * this.fraction));
            }
        }
        // merge and sort both subarrays
        this.measurements = this.measurements[0].concat(this.measurements[1]).sort(function (a,b) {return a-b;});
        return true;
    }
};
scale.create();

// result scale:
// [4, 5, 8, 10, 16, 20, 32, 40, 64, 80, 128, 160, 256, 320, 512, 640, 1024, 1280, 2048, 2560]