ndarray.js (2202B)
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 * Computes the dot product of `x` and `y`. 30 * 31 * @param {integer} N - number of values over which to compute the dot product 32 * @param {NumericArray} x - first input array 33 * @param {integer} strideX - `x` stride length 34 * @param {NonNegativeInteger} offsetX - starting index for `x` 35 * @param {NumericArray} y - second input array 36 * @param {integer} strideY - `y` stride length 37 * @param {NonNegativeInteger} offsetY - starting index for `y` 38 * @returns {number} dot product of `x` and `y` 39 * 40 * @example 41 * var x = [ 4.0, 2.0, -3.0, 5.0, -1.0 ]; 42 * var y = [ 2.0, 6.0, -1.0, -4.0, 8.0 ]; 43 44 * var z = gdot( x.length, x, 1, 0, y, 1, 0 ); 45 * // returns -5.0 46 */ 47 function gdot( N, x, strideX, offsetX, y, strideY, offsetY ) { 48 var dot; 49 var ix; 50 var iy; 51 var m; 52 var i; 53 54 dot = 0.0; 55 if ( N <= 0 ) { 56 return dot; 57 } 58 ix = offsetX; 59 iy = offsetY; 60 61 // Use unrolled loops if both strides are equal to `1`... 62 if ( strideX === 1 && strideY === 1 ) { 63 m = N % M; 64 65 // If we have a remainder, run a clean-up loop... 66 if ( m > 0 ) { 67 for ( i = 0; i < m; i++ ) { 68 dot += ( x[ ix ] * y[ iy ] ); 69 ix += 1; 70 iy += 1; 71 } 72 } 73 if ( N < M ) { 74 return dot; 75 } 76 for ( i = m; i < N; i += M ) { 77 dot += ( x[ix]*y[iy] ) + ( x[ix+1]*y[iy+1] ) + ( x[ix+2]*y[iy+2] ) + ( x[ix+3]*y[iy+3] ) + ( x[ix+4]*y[iy+4] ); // eslint-disable-line max-len 78 ix += M; 79 iy += M; 80 } 81 return dot; 82 } 83 for ( i = 0; i < N; i++ ) { 84 dot += x[ ix ] * y[ iy ]; 85 ix += strideX; 86 iy += strideY; 87 } 88 return dot; 89 } 90 91 92 // EXPORTS // 93 94 module.exports = gdot;