dcusumors.js (1770B)
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 double-precision floating-point strided array elements using ordinary recursive summation. 25 * 26 * @param {PositiveInteger} N - number of indexed elements 27 * @param {number} sum - initial sum 28 * @param {Float64Array} x - input array 29 * @param {integer} strideX - `x` stride length 30 * @param {Float64Array} y - output array 31 * @param {integer} strideY - `y` stride length 32 * @returns {Float64Array} output array 33 * 34 * @example 35 * var Float64Array = require( '@stdlib/array/float64' ); 36 * 37 * var x = new Float64Array( [ 1.0, -2.0, 2.0 ] ); 38 * var y = new Float64Array( x.length ); 39 * var N = x.length; 40 * 41 * var v = dcusumors( N, 0.0, x, 1, y, 1 ); 42 * // returns <Float64Array>[ 1.0, -1.0, 1.0 ] 43 */ 44 function dcusumors( N, sum, x, strideX, y, strideY ) { 45 var ix; 46 var iy; 47 var i; 48 49 if ( N <= 0 ) { 50 return y; 51 } 52 if ( strideX < 0 ) { 53 ix = (1-N) * strideX; 54 } else { 55 ix = 0; 56 } 57 if ( strideY < 0 ) { 58 iy = (1-N) * strideY; 59 } else { 60 iy = 0; 61 } 62 for ( i = 0; i < N; i++ ) { 63 sum += x[ ix ]; 64 y[ iy ] = sum; 65 ix += strideX; 66 iy += strideY; 67 } 68 return y; 69 } 70 71 72 // EXPORTS // 73 74 module.exports = dcusumors;