Function _rndExp

pattern/canvas.js:2501–2510

(bias)

var _RANDOM_MAP = [90.0, 9.00, 4.00, 2.33, 1.50, 1.00, 0.66, 0.43, 0.25, 0.11, 0.01];

function _rndExp(bias) { 
    if (bias === undefined) bias = 0.5;
    bias = Math.max(0, Math.min(bias, 1)) * 10;
    var i = parseInt(Math.floor(bias)); // bias*10 => index in the _map curve.
    var n = _RANDOM_MAP[i];             // If bias is 0.3, rnd()**2.33 will average 0.3.
    if (bias < 10) {
        n += (_RANDOM_MAP[i+1]-n) * (bias-i);
    }
    return n;
}

function random(v1, v2, bias) {
    /* Returns a number between v1 and v2, including v1 but not v2.