85 lines
2.0 KiB
JavaScript
85 lines
2.0 KiB
JavaScript
/**
|
|
* @license Apache-2.0
|
|
*
|
|
* Copyright (c) 2018 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 isPositiveInteger = require( '@stdlib/assert/is-positive-integer' ).isPrimitive;
|
|
var incrmsum = require( './../../../incr/msum' );
|
|
|
|
|
|
// MAIN //
|
|
|
|
/**
|
|
* Returns an accumulator function which incrementally computes a moving sum of products.
|
|
*
|
|
* @param {PositiveInteger} W - window size
|
|
* @throws {TypeError} must provide a positive integer
|
|
* @returns {Function} accumulator function
|
|
*
|
|
* @example
|
|
* var accumulator = incrmsumprod( 3 );
|
|
*
|
|
* var sum = accumulator();
|
|
* // returns null
|
|
*
|
|
* sum = accumulator( 2.0, 3.0 );
|
|
* // returns 6.0
|
|
*
|
|
* sum = accumulator( -5.0, 2.0 );
|
|
* // returns -4.0
|
|
*
|
|
* sum = accumulator( 3.0, -2.0 );
|
|
* // returns -10.0
|
|
*
|
|
* sum = accumulator( 5.0, 3.0 );
|
|
* // returns -1.0
|
|
*
|
|
* sum = accumulator();
|
|
* // returns -1.0
|
|
*/
|
|
function incrmsumprod( W ) {
|
|
var sum;
|
|
if ( !isPositiveInteger( W ) ) {
|
|
throw new TypeError( 'invalid argument. Must provide a positive integer. Value: `' + W + '`.' );
|
|
}
|
|
sum = incrmsum( W );
|
|
return accumulator;
|
|
|
|
/**
|
|
* If provided a value, the accumulator function returns an updated sum. If not provided a value, the accumulator function returns the current sum.
|
|
*
|
|
* @private
|
|
* @param {number} [x] - input value
|
|
* @param {number} [y] - input value
|
|
* @returns {(number|null)} sum or null
|
|
*/
|
|
function accumulator( x, y ) {
|
|
if ( arguments.length === 0 ) {
|
|
return sum();
|
|
}
|
|
return sum( x*y );
|
|
}
|
|
}
|
|
|
|
|
|
// EXPORTS //
|
|
|
|
module.exports = incrmsumprod;
|