sapxsumors.js (1729B)
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 25 26 // MAIN // 27 28 /** 29 * Adds a constant to each single-precision floating-point strided array element and computes the sum using ordinary recursive summation. 30 * 31 * @param {PositiveInteger} N - number of indexed elements 32 * @param {number} alpha - constant 33 * @param {Float32Array} x - input array 34 * @param {integer} stride - stride length 35 * @returns {number} sum 36 * 37 * @example 38 * var Float32Array = require( '@stdlib/array/float32' ); 39 * 40 * var x = new Float32Array( [ 1.0, -2.0, 2.0 ] ); 41 * var N = x.length; 42 * 43 * var v = sapxsumors( N, 5.0, x, 1 ); 44 * // returns 16.0 45 */ 46 function sapxsumors( N, alpha, x, stride ) { 47 var sum; 48 var ix; 49 var i; 50 51 if ( N <= 0 ) { 52 return 0.0; 53 } 54 if ( N === 1 || stride === 0 ) { 55 return float64ToFloat32( alpha + x[ 0 ] ); 56 } 57 if ( stride < 0 ) { 58 ix = (1-N) * stride; 59 } else { 60 ix = 0; 61 } 62 sum = 0.0; 63 for ( i = 0; i < N; i++ ) { 64 sum = float64ToFloat32( sum + float64ToFloat32( alpha+x[ ix ] ) ); 65 ix += stride; 66 } 67 return sum; 68 } 69 70 71 // EXPORTS // 72 73 module.exports = sapxsumors;