dasum.js (1846B)
1 /** 2 * @license Apache-2.0 3 * 4 * Copyright (c) 2018 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 abs = require( '@stdlib/math/base/special/abs' ); 24 25 26 // VARIABLES // 27 28 var M = 6; 29 30 31 // MAIN // 32 33 /** 34 * Computes the sum of absolute values. 35 * 36 * @param {PositiveInteger} N - number of values to sum 37 * @param {Float64Array} x - input array 38 * @param {PositiveInteger} stride - `x` stride length 39 * @returns {number} sum 40 * 41 * @example 42 * var Float64Array = require( '@stdlib/array/float64' ); 43 * 44 * var x = new Float64Array( [ 1.0, -2.0, 3.0, -4.0, 5.0 ] ); 45 * 46 * var s = dasum( x.length, x, 1 ); 47 * // returns 15.0 48 */ 49 function dasum( N, x, stride ) { 50 var sum; 51 var m; 52 var i; 53 54 sum = 0.0; 55 if ( N <= 0 || stride <= 0 ) { 56 return sum; 57 } 58 // Use unrolled loops if the stride is equal to `1`... 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 += abs( x[i] ); 66 } 67 } 68 if ( N < M ) { 69 return sum; 70 } 71 for ( i = m; i < N; i += M ) { 72 sum += abs(x[i]) + abs(x[i+1]) + abs(x[i+2]) + abs(x[i+3]) + abs(x[i+4]) + abs(x[i+5]); // eslint-disable-line max-len 73 } 74 return sum; 75 } 76 N *= stride; 77 for ( i = 0; i < N; i += stride ) { 78 sum += abs( x[i] ); 79 } 80 return sum; 81 } 82 83 84 // EXPORTS // 85 86 module.exports = dasum;