gcusumors.js (1621B)
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 // MAIN // 22 23 /** 24 * Computes the cumulative sum of strided array elements using ordinary recursive summation. 25 * 26 * @param {PositiveInteger} N - number of indexed elements 27 * @param {number} sum - initial sum 28 * @param {NumericArray} x - input array 29 * @param {integer} strideX - `x` stride length 30 * @param {NumericArray} y - output array 31 * @param {integer} strideY - `y` stride length 32 * @returns {NumericArray} output array 33 * 34 * @example 35 * var x = [ 1.0, -2.0, 2.0 ]; 36 * var y = [ 0.0, 0.0, 0.0 ]; 37 * 38 * var v = gcusumors( x.length, 0.0, x, 1, y, 1 ); 39 * // returns [ 1.0, -1.0, 1.0 ] 40 */ 41 function gcusumors( N, sum, x, strideX, y, strideY ) { 42 var ix; 43 var iy; 44 var i; 45 46 if ( N <= 0 ) { 47 return y; 48 } 49 if ( strideX < 0 ) { 50 ix = (1-N) * strideX; 51 } else { 52 ix = 0; 53 } 54 if ( strideY < 0 ) { 55 iy = (1-N) * strideY; 56 } else { 57 iy = 0; 58 } 59 for ( i = 0; i < N; i++ ) { 60 sum += x[ ix ]; 61 y[ iy ] = sum; 62 ix += strideX; 63 iy += strideY; 64 } 65 return y; 66 } 67 68 69 // EXPORTS // 70 71 module.exports = gcusumors;