ndarray.js (2006B)
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 = 5; 24 25 26 // MAIN // 27 28 /** 29 * Adds a constant to each element in a double-precision floating-point strided array. 30 * 31 * @param {PositiveInteger} N - number of indexed elements 32 * @param {number} alpha - scalar 33 * @param {Float64Array} x - input array 34 * @param {integer} stride - index increment 35 * @param {NonNegativeInteger} offset - starting index 36 * @returns {Float64Array} input array 37 * 38 * @example 39 * var Float64Array = require( '@stdlib/array/float64' ); 40 * 41 * var x = new Float64Array( [ 1.0, -2.0, 3.0, -4.0, 5.0, -6.0 ] ); 42 * var alpha = 5.0; 43 * 44 * dapx( 3, alpha, x, 1, x.length-3 ); 45 * // x => <Float64Array>[ 1.0, -2.0, 3.0, 1.0, 10.0, -1.0 ] 46 */ 47 function dapx( N, alpha, x, stride, offset ) { 48 var ix; 49 var m; 50 var i; 51 52 if ( N <= 0 || alpha === 0.0 ) { 53 return x; 54 } 55 ix = offset; 56 57 // Use loop unrolling if the stride is equal to `1`... 58 if ( stride === 1 ) { 59 m = N % M; 60 61 // If we have a remainder, run a clean-up loop... 62 if ( m > 0 ) { 63 for ( i = 0; i < m; i++ ) { 64 x[ ix ] += alpha; 65 ix += stride; 66 } 67 } 68 if ( N < M ) { 69 return x; 70 } 71 for ( i = m; i < N; i += M ) { 72 x[ ix ] += alpha; 73 x[ ix+1 ] += alpha; 74 x[ ix+2 ] += alpha; 75 x[ ix+3 ] += alpha; 76 x[ ix+4 ] += alpha; 77 ix += M; 78 } 79 return x; 80 } 81 for ( i = 0; i < N; i++ ) { 82 x[ ix ] += alpha; 83 ix += stride; 84 } 85 return x; 86 } 87 88 89 // EXPORTS // 90 91 module.exports = dapx;