Get normally distributed random value

getNormal.js

// From <https://github.com/ondras/rot.js/blob/master/src/rng.js>
// I have no idea how this works

function getNormal (mean, stddev) {
		do {
			var u = 2*this.getUniform()-1;
			var v = 2*this.getUniform()-1;
			var r = u*u + v*v;
		} while (r > 1 || r == 0);

		var gauss = u * Math.sqrt(-2*Math.log(r)/r);
		return (mean || 0) + gauss*(stddev || 1);
}

From what I get, Box–Muller transform is utilized.