main.js (1816B)
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 sqrt = require( '@stdlib/math/base/special/sqrt' ); 24 var incrmean = require( './../../../incr/mean' ); 25 26 27 // MAIN // 28 29 /** 30 * Returns an accumulator function which incrementally computes the root mean squared error. 31 * 32 * @returns {Function} accumulator function 33 * 34 * @example 35 * var accumulator = incrrmse(); 36 * 37 * var r = accumulator(); 38 * // returns null 39 * 40 * r = accumulator( 2.0, 3.0 ); 41 * // returns 1.0 42 * 43 * r = accumulator( -5.0, 2.0 ); 44 * // returns 5.0 45 * 46 * r = accumulator(); 47 * // returns 5.0 48 */ 49 function incrrmse() { 50 var mean = incrmean(); 51 return accumulator; 52 53 /** 54 * If provided input values, the accumulator function returns an updated root mean squared error. If not provided input values, the accumulator function returns the current root mean squared error. 55 * 56 * @private 57 * @param {number} [x] - input value 58 * @param {number} [y] - input value 59 * @returns {(number|null)} root mean squared error or null 60 */ 61 function accumulator( x, y ) { 62 var r; 63 if ( arguments.length === 0 ) { 64 r = mean(); 65 if ( r === null ) { 66 return r; 67 } 68 return sqrt( r ); 69 } 70 r = y - x; 71 return sqrt( mean( r*r ) ); 72 } 73 } 74 75 76 // EXPORTS // 77 78 module.exports = incrrmse;