mean.js (1640B)
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 * Returns the expected value of a triangular distribution. 30 * 31 * @param {number} a - minimum support 32 * @param {number} b - maximum support 33 * @param {number} c - mode 34 * @returns {number} expected value 35 * 36 * @example 37 * var v = mean( 0.0, 1.0, 0.5 ); 38 * // returns ~0.5 39 * 40 * @example 41 * var v = mean( 4.0, 12.0, 9.0 ); 42 * // returns ~8.333 43 * 44 * @example 45 * var v = mean( -4.0, 4.0, -1.0 ); 46 * // returns ~-0.333 47 * 48 * @example 49 * var v = mean( 1.0, -0.1, 0.5 ); 50 * // returns NaN 51 * 52 * @example 53 * var v = mean( 0.0, 1.0, 2.0 ); 54 * // returns NaN 55 * 56 * @example 57 * var v = mean( NaN, 4.0, 2.0 ); 58 * // returns NaN 59 * 60 * @example 61 * var v = mean( 0.0, NaN, 2.0 ); 62 * // returns NaN 63 * 64 * @example 65 * var v = mean( 0.0, 4.0, NaN ); 66 * // returns NaN 67 */ 68 function mean( a, b, c ) { 69 if ( 70 isnan( a ) || 71 isnan( b ) || 72 isnan( c ) || 73 !( a <= c && c <= b ) 74 ) { 75 return NaN; 76 } 77 return ( a + b + c ) / 3.0; 78 } 79 80 81 // EXPORTS // 82 83 module.exports = mean;