File size: 716 Bytes
bc20498 |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 |
import defaultSource from "./defaultSource.js";
export default (function sourceRandomNormal(source) {
function randomNormal(mu, sigma) {
var x, r;
mu = mu == null ? 0 : +mu;
sigma = sigma == null ? 1 : +sigma;
return function() {
var y;
// If available, use the second previously-generated uniform random.
if (x != null) y = x, x = null;
// Otherwise, generate a new x and y.
else do {
x = source() * 2 - 1;
y = source() * 2 - 1;
r = x * x + y * y;
} while (!r || r > 1);
return mu + sigma * y * Math.sqrt(-2 * Math.log(r) / r);
};
}
randomNormal.source = sourceRandomNormal;
return randomNormal;
})(defaultSource);
|