ndarray.js (1960B)
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 {integer} stride - `x` stride length 39 * @param {NonNegativeInteger} offset - starting `x` index 40 * @returns {number} sum 41 * 42 * @example 43 * var Float64Array = require( '@stdlib/array/float64' ); 44 * 45 * var x = new Float64Array( [ 1.0, -2.0, 3.0, -4.0, 5.0 ] ); 46 * 47 * var s = dasum( x.length, x, 1, 0 ); 48 * // returns 15.0 49 */ 50 function dasum( N, x, stride, offset ) { 51 var sum; 52 var ix; 53 var m; 54 var i; 55 56 sum = 0.0; 57 if ( N <= 0 ) { 58 return sum; 59 } 60 ix = offset; 61 62 // Use unrolled loops if the stride is equal to `1`... 63 if ( stride === 1 ) { 64 m = N % M; 65 66 // If we have a remainder, run a clean-up loop... 67 if ( m > 0 ) { 68 for ( i = 0; i < m; i++ ) { 69 sum += abs( x[ix] ); 70 ix += stride; 71 } 72 } 73 if ( N < M ) { 74 return sum; 75 } 76 for ( i = m; i < N; i += M ) { 77 sum += abs( x[ix] ) + abs( x[ix+1] ) + abs( x[ix+2] ) + abs( x[ix+3] ) + abs( x[ix+4] ) + abs( x[ix+5] ); // eslint-disable-line max-len 78 ix += M; 79 } 80 return sum; 81 } 82 for ( i = 0; i < N; i++ ) { 83 sum += abs( x[ix] ); 84 ix += stride; 85 } 86 return sum; 87 } 88 89 90 // EXPORTS // 91 92 module.exports = dasum;