sasum.js (1471B)
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 var float64ToFloat32 = require( '@stdlib/number/float64/base/to-float32' ); 25 26 27 // MAIN // 28 29 /** 30 * Computes the sum of absolute values. 31 * 32 * @param {PositiveInteger} N - number of values to sum 33 * @param {Float32Array} x - input array 34 * @param {PositiveInteger} stride - `x` 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, 3.0, -4.0, 5.0 ] ); 41 * 42 * var s = sasum( x.length, x, 1 ); 43 * // returns 15.0 44 */ 45 function sasum( N, x, stride ) { 46 var sum; 47 var i; 48 49 sum = 0.0; 50 if ( N <= 0 || stride <= 0 ) { 51 return sum; 52 } 53 N *= stride; 54 for ( i = 0; i < N; i += stride ) { 55 sum = float64ToFloat32( sum + abs( x[i] ) ); 56 } 57 return sum; 58 } 59 60 61 // EXPORTS // 62 63 module.exports = sasum;