ndarray.js (1684B)
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 // MAIN // 22 23 /** 24 * Adds a constant to each double-precision floating-point strided array element and computes the sum using ordinary recursive summation. 25 * 26 * @param {PositiveInteger} N - number of indexed elements 27 * @param {number} alpha - constant 28 * @param {Float64Array} x - input array 29 * @param {integer} stride - stride length 30 * @param {NonNegativeInteger} offset - starting index 31 * @returns {number} sum 32 * 33 * @example 34 * var Float64Array = require( '@stdlib/array/float64' ); 35 * var floor = require( '@stdlib/math/base/special/floor' ); 36 * 37 * var x = new Float64Array( [ 2.0, 1.0, 2.0, -2.0, -2.0, 2.0, 3.0, 4.0 ] ); 38 * var N = floor( x.length / 2 ); 39 * 40 * var v = dapxsumors( N, 5.0, x, 2, 1 ); 41 * // returns 25.0 42 */ 43 function dapxsumors( N, alpha, x, stride, offset ) { 44 var sum; 45 var ix; 46 var i; 47 48 if ( N <= 0 ) { 49 return 0.0; 50 } 51 if ( N === 1 || stride === 0 ) { 52 return alpha + x[ 0 ]; 53 } 54 ix = offset; 55 sum = 0.0; 56 for ( i = 0; i < N; i++ ) { 57 sum += alpha + x[ ix ]; 58 ix += stride; 59 } 60 return sum; 61 } 62 63 64 // EXPORTS // 65 66 module.exports = dapxsumors;