main.js (1604B)
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 abs = require( '@stdlib/math/base/special/abs' ); 24 25 26 // MAIN // 27 28 /** 29 * Returns an accumulator function which incrementally computes a sum of absolute values. 30 * 31 * @returns {Function} accumulator function 32 * 33 * @example 34 * var accumulator = incrsumabs(); 35 * 36 * var sum = accumulator(); 37 * // returns null 38 * 39 * sum = accumulator( 2.0 ); 40 * // returns 2.0 41 * 42 * sum = accumulator( -5.0 ); 43 * // returns 7.0 44 * 45 * sum = accumulator(); 46 * // returns 7.0 47 */ 48 function incrsumabs() { 49 var sum = 0.0; 50 var FLG; 51 return accumulator; 52 53 /** 54 * If provided a value, the accumulator function returns an updated sum. If not provided a value, the accumulator function returns the current sum. 55 * 56 * @private 57 * @param {number} [x] - new value 58 * @returns {(number|null)} sum or null 59 */ 60 function accumulator( x ) { 61 if ( arguments.length === 0 ) { 62 return ( FLG ) ? sum : null; 63 } 64 FLG = true; 65 sum += abs( x ); 66 return sum; 67 } 68 } 69 70 71 // EXPORTS // 72 73 module.exports = incrsumabs;