median.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 isNonNegativeInteger = require( '@stdlib/math/base/assert/is-nonnegative-integer' ); 24 var isnan = require( '@stdlib/math/base/assert/is-nan' ); 25 var round = require( '@stdlib/math/base/special/round' ); 26 var mean = require( './../../../../../base/dists/binomial/mean' ); 27 var PINF = require( '@stdlib/constants/float64/pinf' ); 28 29 30 // MAIN // 31 32 /** 33 * Returns the median of a binomial distribution. 34 * 35 * @param {NonNegativeInteger} n - number of trials 36 * @param {Probability} p - success probability 37 * @returns {NonNegativeInteger} median 38 * 39 * @example 40 * var v = median( 100, 0.1 ); 41 * // returns 10 42 * 43 * @example 44 * var v = median( 20, 0.5 ); 45 * // returns 10 46 * 47 * @example 48 * var v = median( 10.3, 0.5 ); 49 * // returns NaN 50 * 51 * @example 52 * var v = median( 20, 1.1 ); 53 * // returns NaN 54 * 55 * @example 56 * var v = median( 20, NaN ); 57 * // returns NaN 58 */ 59 function median( n, p ) { 60 if ( 61 isnan( n ) || 62 isnan( p ) || 63 p < 0.0 || 64 p > 1.0 || 65 !isNonNegativeInteger( n ) || 66 n === PINF 67 ) { 68 return NaN; 69 } 70 return round( mean( n, p ) ); 71 } 72 73 74 // EXPORTS // 75 76 module.exports = median;