text: // Copyright (c) 2019 Uber Technologies, Inc.
  //
  // Permission is hereby granted, free of charge, to any person obtaining a copy
  // of this software and associated documentation files (the "Software"), to deal
  // in the Software without restriction, including without limitation the rights
  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  // copies of the Software, and to permit persons to whom the Software is
  // furnished to do so, subject to the following conditions:
  //
  // The above copyright notice and this permission notice shall be included in
  // all copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  // THE SOFTWARE.
  
  'use strict';
  
  // Random sampling functions borrowed from python standard library
  
  var RandomSample = module.exports;
  RandomSample.variate = {};
  
  RandomSample.variate.norm = function normalvariate(mu, sigma, random) {
      var nvMagicConst = 4 * Math.exp(-0.5) / Math.sqrt(2.0);
      return function sampleNormalRandom() {
          for (;;) {
              var u1 = random();
              var u2 = 1.0 - random();
              var z = nvMagicConst * (u1 - 0.5) / u2;
              var zz = z * z / 4.0;
              if (zz <= -Math.log(u2)) {
                  return mu + z * sigma;
              }
          }
      };
  };
  
  RandomSample.variate.expo = function expovariate(mu, random) {
      return function sampleExponentialRandom() {
          return -Math.log(1 - random()) * mu;
      };
  };
  
  RandomSample.fromString = function fromString(str, random) {
      if (!random) {
          random = Math.random;
      }
  
      // norm:mu,sigma
      // expo:mu
      var match = /^(\w+):(.+)$/.exec(str);
      if (!match) {
          throw new Error('invalid random sample spec, expected "kind:arg[,arg[,...]]"');
      }
      var kind = match[1];
      str = match[2];
  
      var variate = RandomSample.variate[kind];
      if (!variate) {
          throw new Error('invalid random sample kind ' + kind);
      }
  
      var args = str.split(',');
      if (args.length !== variate.length - 1) {
          throw new Error('wrong number of args for random sample kind ' + kind);
      }
  
      for (var i = 0; i < args.length; i++) {
          var n = parseFloat(args[i]);
          if (isNaN(n)) {
              throw new Error('invalid argument, not a number: ' + args[i]);
          }
          args[i] = n;
      }
  
      args.push(random);
      return variate.apply(null, args);
  };
  