time-to-botec/squiggle/node_modules/@stdlib/stats/base/smeankbn/lib/smeankbn.js

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/**
* @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 float64ToFloat32 = require( '@stdlib/number/float64/base/to-float32' );
var ssumkbn = require( '@stdlib/blas/ext/base/ssumkbn' );
// MAIN //
/**
* Computes the arithmetic mean of a single-precision floating-point strided array using an improved KahanBabuška algorithm.
*
* ## Method
*
* - This implementation uses an "improved KahanBabuška 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): 3951. doi:[10.1002/zamm.19740540106](https://doi.org/10.1002/zamm.19740540106).
*
* @param {PositiveInteger} N - number of indexed elements
* @param {Float32Array} x - input array
* @param {integer} stride - stride length
* @returns {number} arithmetic mean
*
* @example
* var Float32Array = require( '@stdlib/array/float32' );
*
* var x = new Float32Array( [ 1.0, -2.0, 2.0 ] );
* var N = x.length;
*
* var v = smeankbn( N, x, 1 );
* // returns ~0.3333
*/
function smeankbn( N, x, stride ) {
if ( N <= 0 ) {
return NaN;
}
if ( N === 1 || stride === 0 ) {
return x[ 0 ];
}
return float64ToFloat32( ssumkbn( N, x, stride ) / N );
}
// EXPORTS //
module.exports = smeankbn;