kumaraswamy.js (1195B)
1 /** 2 * @license Apache-2.0 3 * 4 * Copyright (c) 2018 The Stdlib Authors. 5 * 6 * Licensed under the Apache License, Version 2.0 (the "License"); 7 * you may not use this file except in compliance with the License. 8 * You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, software 13 * distributed under the License is distributed on an "AS IS" BASIS, 14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 * See the License for the specific language governing permissions and 16 * limitations under the License. 17 */ 18 19 'use strict'; 20 21 // MODULES // 22 23 var pow = require( '@stdlib/math/base/special/pow' ); 24 25 26 // MAIN // 27 28 /** 29 * Returns a random number drawn from Kumaraswamy's double bounded distribution. 30 * 31 * @private 32 * @param {PRNG} rand - pseudorandom number generator for uniformly distributed numbers 33 * @param {PositiveNumber} a - first shape parameter 34 * @param {PositiveNumber} b - second shape parameter 35 * @returns {Probability} pseudorandom number 36 */ 37 function sample( rand, a, b ) { 38 var u = rand(); 39 return pow( 1.0 - pow( 1.0-u, 1.0/b ), 1.0/a ); 40 } 41 42 43 // EXPORTS // 44 45 module.exports = sample;