72 lines
1.6 KiB
JavaScript
72 lines
1.6 KiB
JavaScript
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/**
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* @license Apache-2.0
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*
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* Copyright (c) 2018 The Stdlib Authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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'use strict';
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// MODULES //
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var incrsum = require( './../../../incr/sum' );
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// MAIN //
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/**
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* Returns an accumulator function which incrementally computes a sum of products.
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*
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* @returns {Function} accumulator function
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*
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* @example
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* var accumulator = incrsumprod();
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*
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* var sum = accumulator();
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* // returns null
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*
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* sum = accumulator( 2.0, 3.0 );
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* // returns 6.0
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*
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* sum = accumulator( -5.0, 2.0 );
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* // returns -4.0
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*
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* sum = accumulator();
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* // returns -4.0
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*/
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function incrsumprod() {
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var sum = incrsum();
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return accumulator;
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/**
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* If provided input values, the accumulator function returns an updated sum. If not provided input values, the accumulator function returns the current sum.
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*
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* @private
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* @param {number} [x] - first value
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* @param {number} [y] - second value
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* @returns {(number|null)} sum-product or null
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*/
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function accumulator( x, y ) {
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if ( arguments.length === 0 ) {
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return sum();
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}
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return sum( x*y );
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}
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}
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// EXPORTS //
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module.exports = incrsumprod;
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