factory.js (1739B)
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 constantFunction = require( '@stdlib/utils/constant-function' ); 24 var isnan = require( '@stdlib/math/base/assert/is-nan' ); 25 26 27 // MAIN // 28 29 /** 30 * Returns a function for evaluating the quantile function for a Bernoulli distribution with success probability `p`. 31 * 32 * @param {Probability} p - success probability 33 * @returns {Function} quantile function 34 * 35 * @example 36 * var quantile = factory( 0.4 ); 37 * var y = quantile( 0.4 ); 38 * // returns 0 39 * 40 * y = quantile( 0.8 ); 41 * // returns 1 42 * 43 * y = quantile( 1.0 ); 44 * // returns 1 45 */ 46 function factory( p ) { 47 if ( isnan( p ) || p < 0.0 || p > 1.0 ) { 48 return constantFunction( NaN ); 49 } 50 return quantile; 51 52 /** 53 * Evaluates the quantile function for a Bernoulli distribution. 54 * 55 * @private 56 * @param {Probability} r - input value 57 * @returns {NonNegativeInteger} evaluated quantile function 58 * 59 * @example 60 * var y = quantile( 0.3 ); 61 * // returns <number> 62 */ 63 function quantile( r ) { 64 if ( isnan( r ) || r < 0.0 || r > 1.0 ) { 65 return NaN; 66 } 67 if ( r <= 1.0 - p ) { 68 return 0; 69 } 70 return 1; 71 } 72 } 73 74 75 // EXPORTS // 76 77 module.exports = factory;