main.js (1543B)
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 // MAIN // 22 23 /** 24 * Returns an accumulator function which incrementally computes a sum of squared absolute values. 25 * 26 * @returns {Function} accumulator function 27 * 28 * @example 29 * var accumulator = incrsumabs2(); 30 * 31 * var sum = accumulator(); 32 * // returns null 33 * 34 * sum = accumulator( 2.0 ); 35 * // returns 4.0 36 * 37 * sum = accumulator( -5.0 ); 38 * // returns 29.0 39 * 40 * sum = accumulator(); 41 * // returns 29.0 42 */ 43 function incrsumabs2() { 44 var sum = 0.0; 45 var FLG; 46 return accumulator; 47 48 /** 49 * If provided a value, the accumulator function returns an updated sum. If not provided a value, the accumulator function returns the current sum. 50 * 51 * @private 52 * @param {number} [x] - new value 53 * @returns {(number|null)} sum or null 54 */ 55 function accumulator( x ) { 56 if ( arguments.length === 0 ) { 57 return ( FLG ) ? sum : null; 58 } 59 FLG = true; 60 sum += x * x; 61 return sum; 62 } 63 } 64 65 66 // EXPORTS // 67 68 module.exports = incrsumabs2;