dssumors.js (1960B)
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 // VARIABLES // 22 23 var M = 6; 24 25 26 // MAIN // 27 28 /** 29 * Computes the sum of single-precision floating-point strided array elements using ordinary recursive summation with extended accumulation and returning an extended precision result. 30 * 31 * @param {PositiveInteger} N - number of indexed elements 32 * @param {Float32Array} x - input array 33 * @param {integer} stride - stride length 34 * @returns {number} sum 35 * 36 * @example 37 * var Float32Array = require( '@stdlib/array/float32' ); 38 * 39 * var x = new Float32Array( [ 1.0, -2.0, 2.0 ] ); 40 * var N = x.length; 41 * 42 * var v = dssumors( N, x, 1 ); 43 * // returns 1.0 44 */ 45 function dssumors( N, x, stride ) { 46 var sum; 47 var ix; 48 var m; 49 var i; 50 51 sum = 0.0; 52 if ( N <= 0 ) { 53 return sum; 54 } 55 if ( N === 1 || stride === 0 ) { 56 return x[ 0 ]; 57 } 58 // If the stride is equal to `1`, use unrolled loops... 59 if ( stride === 1 ) { 60 m = N % M; 61 62 // If we have a remainder, run a clean-up loop... 63 if ( m > 0 ) { 64 for ( i = 0; i < m; i++ ) { 65 sum += x[ i ]; 66 } 67 } 68 if ( N < M ) { 69 return sum; 70 } 71 for ( i = m; i < N; i += M ) { 72 sum += x[i] + x[i+1] + x[i+2] + x[i+3] + x[i+4] + x[i+5]; 73 } 74 return sum; 75 } 76 if ( stride < 0 ) { 77 ix = (1-N) * stride; 78 } else { 79 ix = 0; 80 } 81 for ( i = 0; i < N; i++ ) { 82 sum += x[ ix ]; 83 ix += stride; 84 } 85 return sum; 86 } 87 88 89 // EXPORTS // 90 91 module.exports = dssumors;