time-to-botec

Benchmark sampling in different programming languages
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smeankbn.js (1916B)

      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 float64ToFloat32 = require( '@stdlib/number/float64/base/to-float32' );
     24 var ssumkbn = require( '@stdlib/blas/ext/base/ssumkbn' );
     25 
     26 
     27 // MAIN //
     28 
     29 /**
     30 * Computes the arithmetic mean of a single-precision floating-point strided array using an improved Kahan–Babuška algorithm.
     31 *
     32 * ## Method
     33 *
     34 * -   This implementation uses an "improved Kahan–Babuška algorithm", as described by Neumaier (1974).
     35 *
     36 * ## References
     37 *
     38 * -   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).
     39 *
     40 * @param {PositiveInteger} N - number of indexed elements
     41 * @param {Float32Array} x - input array
     42 * @param {integer} stride - stride length
     43 * @returns {number} arithmetic mean
     44 *
     45 * @example
     46 * var Float32Array = require( '@stdlib/array/float32' );
     47 *
     48 * var x = new Float32Array( [ 1.0, -2.0, 2.0 ] );
     49 * var N = x.length;
     50 *
     51 * var v = smeankbn( N, x, 1 );
     52 * // returns ~0.3333
     53 */
     54 function smeankbn( N, x, stride ) {
     55 	if ( N <= 0 ) {
     56 		return NaN;
     57 	}
     58 	if ( N === 1 || stride === 0 ) {
     59 		return x[ 0 ];
     60 	}
     61 	return float64ToFloat32( ssumkbn( N, x, stride ) / N );
     62 }
     63 
     64 
     65 // EXPORTS //
     66 
     67 module.exports = smeankbn;