time-to-botec

Benchmark sampling in different programming languages
Log | Files | Refs | README

dnannsumpw.js (2105B)

      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 sumpw = require( './sumpw.js' );
     24 
     25 
     26 // MAIN //
     27 
     28 /**
     29 * Computes the sum of double-precision floating-point strided array elements, ignoring `NaN` values and using pairwise summation.
     30 *
     31 * ## Method
     32 *
     33 * -   This implementation uses pairwise summation, which accrues rounding error `O(log2 N)` instead of `O(N)`. The recursion depth is also `O(log2 N)`.
     34 *
     35 * ## References
     36 *
     37 * -   Higham, Nicholas J. 1993. "The Accuracy of Floating Point Summation." _SIAM Journal on Scientific Computing_ 14 (4): 783–99. doi:[10.1137/0914050](https://doi.org/10.1137/0914050).
     38 *
     39 * @param {PositiveInteger} N - number of indexed elements
     40 * @param {Float64Array} x - input array
     41 * @param {integer} strideX - `x` stride length
     42 * @param {Float64Array} out - output array
     43 * @param {integer} strideOut - `out` stride length
     44 * @returns {Float64Array} output array
     45 *
     46 * @example
     47 * var Float64Array = require( '@stdlib/array/float64' );
     48 *
     49 * var x = new Float64Array( [ 1.0, -2.0, NaN, 2.0 ] );
     50 * var out = new Float64Array( 2 );
     51 *
     52 * var v = dnannsumpw( x.length, x, 1, out, 1 );
     53 * // returns <Float64Array>[ 1.0, 3 ]
     54 */
     55 function dnannsumpw( N, x, strideX, out, strideOut ) {
     56 	var ix;
     57 	var io;
     58 	if ( strideX < 0 ) {
     59 		ix = (1-N) * strideX;
     60 	} else {
     61 		ix = 0;
     62 	}
     63 	if ( strideOut < 0 ) {
     64 		io = -strideOut;
     65 	} else {
     66 		io = 0;
     67 	}
     68 	out[ io ] = 0.0;
     69 	out[ io+strideOut ] = 0;
     70 	sumpw( N, x, strideX, ix, out, strideOut, io );
     71 	return out;
     72 }
     73 
     74 
     75 // EXPORTS //
     76 
     77 module.exports = dnannsumpw;