dmeankbn.js (1820B)
1 /** 2 * @license Apache-2.0 3 * 4 * Copyright (c) 2020 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 dsumkbn = require( '@stdlib/blas/ext/base/dsumkbn' ); 24 25 26 // MAIN // 27 28 /** 29 * Computes the arithmetic mean of a double-precision floating-point strided array using an improved Kahan–Babuška algorithm. 30 * 31 * ## Method 32 * 33 * - This implementation uses an "improved Kahan–Babuška algorithm", as described by Neumaier (1974). 34 * 35 * ## References 36 * 37 * - Neumaier, Arnold. 1974. "Rounding Error Analysis of Some Methods for Summing Finite Sums." _Zeitschrift Für Angewandte Mathematik Und Mechanik_ 54 (1): 39–51. doi:[10.1002/zamm.19740540106](https://doi.org/10.1002/zamm.19740540106). 38 * 39 * @param {PositiveInteger} N - number of indexed elements 40 * @param {Float64Array} x - input array 41 * @param {integer} stride - stride length 42 * @returns {number} arithmetic mean 43 * 44 * @example 45 * var Float64Array = require( '@stdlib/array/float64' ); 46 * 47 * var x = new Float64Array( [ 1.0, -2.0, 2.0 ] ); 48 * var N = x.length; 49 * 50 * var v = dmeankbn( N, x, 1 ); 51 * // returns ~0.3333 52 */ 53 function dmeankbn( N, x, stride ) { 54 if ( N <= 0 ) { 55 return NaN; 56 } 57 if ( N === 1 || stride === 0 ) { 58 return x[ 0 ]; 59 } 60 return dsumkbn( N, x, stride ) / N; 61 } 62 63 64 // EXPORTS // 65 66 module.exports = dmeankbn;