All files / base/gcusumors/lib ndarray.js

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/**
* @license Apache-2.0
*
* Copyright (c) 2020 The Stdlib Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*    http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
 
'use strict';
 
// MODULES //
 
var arraylike2object = require( '@stdlib/array/base/arraylike2object' );
var accessors = require( './accessors.js' );
 
 
// MAIN //
 
/**
* Computes the cumulative sum of strided array elements using ordinary recursive summation.
*
* @param {PositiveInteger} N - number of indexed elements
* @param {number} sum - initial sum
* @param {NumericArray} x - input array
* @param {integer} strideX - stride length for `x`
* @param {NonNegativeInteger} offsetX - starting index for `x`
* @param {NumericArray} y - output array
* @param {integer} strideY - stride length for `y`
* @param {NonNegativeInteger} offsetY - starting index for `y`
* @returns {NumericArray} output array
*
* @example
* var x = [ 2.0, 1.0, 2.0, -2.0, -2.0, 2.0, 3.0, 4.0 ];
* var y = [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ];
*
* gcusumors( 4, 0.0, x, 2, 1, y, 1, 0 );
* // y => [ 1.0, -1.0, 1.0, 5.0, 0.0, 0.0, 0.0, 0.0 ]
*/
function gcusumors( N, sum, x, strideX, offsetX, y, strideY, offsetY ) {
	var ix;
	var iy;
	var ox;
	var oy;
	var i;

	if ( N <= 0 ) {
		return y;
	}
	ox = arraylike2object( x );
	oy = arraylike2object( y );
	if ( ox.accessorProtocol || oy.accessorProtocol ) {
		accessors( N, sum, ox, strideX, offsetX, oy, strideY, offsetY );
		return y;
	}
	ix = offsetX;
	iy = offsetY;
	for ( i = 0; i < N; i++ ) {
		sum += x[ ix ];
		y[ iy ] = sum;
		ix += strideX;
		iy += strideY;
	}
	return y;
}
 
 
// EXPORTS //
 
module.exports = gcusumors;