time-to-botec

Benchmark sampling in different programming languages
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ndarray.js (2098B)

      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' ).ndarray;
     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 * @param {NonNegativeInteger} offset - starting index
     44 * @returns {number} arithmetic mean
     45 *
     46 * @example
     47 * var Float32Array = require( '@stdlib/array/float32' );
     48 * var floor = require( '@stdlib/math/base/special/floor' );
     49 *
     50 * var x = new Float32Array( [ 2.0, 1.0, 2.0, -2.0, -2.0, 2.0, 3.0, 4.0 ] );
     51 * var N = floor( x.length / 2 );
     52 *
     53 * var v = smeankbn( N, x, 2, 1 );
     54 * // returns 1.25
     55 */
     56 function smeankbn( N, x, stride, offset ) {
     57 	if ( N <= 0 ) {
     58 		return NaN;
     59 	}
     60 	if ( N === 1 || stride === 0 ) {
     61 		return x[ offset ];
     62 	}
     63 	return float64ToFloat32( ssumkbn( N, x, stride, offset ) / N );
     64 }
     65 
     66 
     67 // EXPORTS //
     68 
     69 module.exports = smeankbn;