d3-random/src/weibull.js

Generate random numbers from various distributions.

import defaultSource from "./defaultSource.js";

export default (function sourceRandomWeibull(source) {
  function randomWeibull(k, a, b) {
    var outerFunc;
    if ((k = +k) === 0) {
      outerFunc = x => -Math.log(x);
    } else {
      k = 1 / k;
      outerFunc = x => Math.pow(x, k);
    }
    a = a == null ? 0 : +a;
    b = b == null ? 1 : +b;
    return function() {
      return a + b * outerFunc(-Math.log1p(-source()));
    };
  }

  randomWeibull.source = sourceRandomWeibull;

  return randomWeibull;
})(defaultSource);