main.js (1622B)
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 incrsum = require( './../../../incr/sum' ); 24 25 26 // MAIN // 27 28 /** 29 * Returns an accumulator function which incrementally computes a sum of products. 30 * 31 * @returns {Function} accumulator function 32 * 33 * @example 34 * var accumulator = incrsumprod(); 35 * 36 * var sum = accumulator(); 37 * // returns null 38 * 39 * sum = accumulator( 2.0, 3.0 ); 40 * // returns 6.0 41 * 42 * sum = accumulator( -5.0, 2.0 ); 43 * // returns -4.0 44 * 45 * sum = accumulator(); 46 * // returns -4.0 47 */ 48 function incrsumprod() { 49 var sum = incrsum(); 50 return accumulator; 51 52 /** 53 * If provided input values, the accumulator function returns an updated sum. If not provided input values, the accumulator function returns the current sum. 54 * 55 * @private 56 * @param {number} [x] - first value 57 * @param {number} [y] - second value 58 * @returns {(number|null)} sum-product or null 59 */ 60 function accumulator( x, y ) { 61 if ( arguments.length === 0 ) { 62 return sum(); 63 } 64 return sum( x*y ); 65 } 66 } 67 68 69 // EXPORTS // 70 71 module.exports = incrsumprod;