quantile.js (1713B)
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 isnan = require( '@stdlib/math/base/assert/is-nan' ); 24 25 26 // MAIN // 27 28 /** 29 * Evaluates the quantile function for a Bernoulli distribution with success probability `p` at a probability `r`. 30 * 31 * @param {Probability} r - input value 32 * @param {Probability} p - success probability 33 * @returns {NonNegativeInteger} evaluated quantile function 34 * 35 * @example 36 * var y = quantile( 0.8, 0.4 ); 37 * // returns 1 38 * 39 * @example 40 * var y = quantile( 0.5, 0.4 ); 41 * // returns 0 42 * 43 * @example 44 * var y = quantile( 0.8, 0.1 ); 45 * // returns 0 46 * 47 * @example 48 * var y = quantile( -0.2, 0.1 ); 49 * // returns NaN 50 * 51 * @example 52 * var y = quantile( NaN, 0.8 ); 53 * // returns NaN 54 * 55 * @example 56 * var y = quantile( 0.4, NaN ); 57 * // returns NaN 58 * 59 * @example 60 * var y = quantile( 0.5, -1.0 ); 61 * // returns NaN 62 * 63 * @example 64 * var y = quantile( 0.5, 1.5 ); 65 * // returns NaN 66 */ 67 function quantile( r, p ) { 68 if ( 69 isnan( p ) || 70 isnan( r ) || 71 p < 0.0 || 72 p > 1.0 || 73 r < 0.0 || 74 r > 1.0 75 ) { 76 return NaN; 77 } 78 if ( r <= 1.0 - p ) { 79 return 0; 80 } 81 return 1; 82 } 83 84 85 // EXPORTS // 86 87 module.exports = quantile;