72 lines
1.6 KiB
JavaScript
72 lines
1.6 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 incrsum = require( './../../../incr/sum' );
|
|
|
|
|
|
// MAIN //
|
|
|
|
/**
|
|
* Returns an accumulator function which incrementally computes a sum of products.
|
|
*
|
|
* @returns {Function} accumulator function
|
|
*
|
|
* @example
|
|
* var accumulator = incrsumprod();
|
|
*
|
|
* 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();
|
|
* // returns -4.0
|
|
*/
|
|
function incrsumprod() {
|
|
var sum = incrsum();
|
|
return accumulator;
|
|
|
|
/**
|
|
* If provided input values, the accumulator function returns an updated sum. If not provided input values, the accumulator function returns the current sum.
|
|
*
|
|
* @private
|
|
* @param {number} [x] - first value
|
|
* @param {number} [y] - second value
|
|
* @returns {(number|null)} sum-product or null
|
|
*/
|
|
function accumulator( x, y ) {
|
|
if ( arguments.length === 0 ) {
|
|
return sum();
|
|
}
|
|
return sum( x*y );
|
|
}
|
|
}
|
|
|
|
|
|
// EXPORTS //
|
|
|
|
module.exports = incrsumprod;
|