factory.js (1723B)
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 of a degenerate distribution centered at a provided mean value. 31 * 32 * @param {number} mu - value at which to center the distribution 33 * @returns {Function} function to evaluate the quantile function 34 * 35 * @example 36 * var quantile = factory( 5.0 ); 37 * 38 * var y = quantile( 0.3 ); 39 * // returns 5.0 40 * 41 * y = quantile( 0.1 ); 42 * // returns 5.0 43 * 44 * y = quantile( 1.1 ); 45 * // returns NaN 46 */ 47 function factory( mu ) { 48 if ( isnan( mu ) ) { 49 return constantFunction( NaN ); 50 } 51 return quantile; 52 53 /** 54 * Evaluates the quantile function of a degenerate distribution. 55 * 56 * @private 57 * @param {Probability} p - input value 58 * @returns {number} evaluated quantile function 59 * 60 * @example 61 * var y = quantile( 0.5 ); 62 * // returns <number> 63 */ 64 function quantile( p ) { 65 if ( isnan( p ) || p < 0.0 || p > 1.0 ) { 66 return NaN; 67 } 68 return mu; 69 } 70 } 71 72 73 // EXPORTS // 74 75 module.exports = factory;