67 lines
1.8 KiB
JavaScript
67 lines
1.8 KiB
JavaScript
|
/**
|
|||
|
|
* @license Apache-2.0
|
|||
|
|
*
|
|||
|
|
* Copyright (c) 2020 The Stdlib Authors.
|
|||
|
|
*
|
|||
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
|||
|
|
* you may not use this file except in compliance with the License.
|
|||
|
|
* You may obtain a copy of the License at
|
|||
|
|
*
|
|||
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|||
|
|
*
|
|||
|
|
* Unless required by applicable law or agreed to in writing, software
|
|||
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
|||
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|||
|
|
* See the License for the specific language governing permissions and
|
|||
|
|
* limitations under the License.
|
|||
|
|
*/
|
|||
|
|
|
|||
|
|
'use strict';
|
|||
|
|
|
|||
|
|
// MODULES //
|
|||
|
|
|
|||
|
|
var dsumkbn = require( '@stdlib/blas/ext/base/dsumkbn' );
|
|||
|
|
|
|||
|
|
|
|||
|
|
// MAIN //
|
|||
|
|
|
|||
|
|
/**
|
|||
|
|
* Computes the arithmetic mean of a double-precision floating-point strided array using an improved Kahan–Babuška algorithm.
|
|||
|
|
*
|
|||
|
|
* ## Method
|
|||
|
|
*
|
|||
|
|
* - This implementation uses an "improved Kahan–Babuška algorithm", as described by Neumaier (1974).
|
|||
|
|
*
|
|||
|
|
* ## References
|
|||
|
|
*
|
|||
|
|
* - 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).
|
|||
|
|
*
|
|||
|
|
* @param {PositiveInteger} N - number of indexed elements
|
|||
|
|
* @param {Float64Array} x - input array
|
|||
|
|
* @param {integer} stride - stride length
|
|||
|
|
* @returns {number} arithmetic mean
|
|||
|
|
*
|
|||
|
|
* @example
|
|||
|
|
* var Float64Array = require( '@stdlib/array/float64' );
|
|||
|
|
*
|
|||
|
|
* var x = new Float64Array( [ 1.0, -2.0, 2.0 ] );
|
|||
|
|
* var N = x.length;
|
|||
|
|
*
|
|||
|
|
* var v = dmeankbn( N, x, 1 );
|
|||
|
|
* // returns ~0.3333
|
|||
|
|
*/
|
|||
|
|
function dmeankbn( N, x, stride ) {
|
|||
|
|
if ( N <= 0 ) {
|
|||
|
|
return NaN;
|
|||
|
|
}
|
|||
|
|
if ( N === 1 || stride === 0 ) {
|
|||
|
|
return x[ 0 ];
|
|||
|
|
}
|
|||
|
|
return dsumkbn( N, x, stride ) / N;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
|
|||
|
|
// EXPORTS //
|
|||
|
|
|
|||
|
|
module.exports = dmeankbn;
|