69 lines
1.5 KiB
JavaScript
69 lines
1.5 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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// MAIN //
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/**
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* Returns an accumulator function which incrementally computes a sum of squared absolute values.
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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 = incrsumabs2();
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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 );
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* // returns 4.0
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*
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* sum = accumulator( -5.0 );
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* // returns 29.0
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*
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* sum = accumulator();
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* // returns 29.0
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*/
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function incrsumabs2() {
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var sum = 0.0;
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var FLG;
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return accumulator;
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/**
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* If provided a value, the accumulator function returns an updated sum. If not provided a value, the accumulator function returns the current sum.
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*
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* @private
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* @param {number} [x] - new value
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* @returns {(number|null)} sum or null
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*/
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function accumulator( x ) {
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if ( arguments.length === 0 ) {
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return ( FLG ) ? sum : null;
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}
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FLG = true;
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sum += x * x;
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return sum;
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}
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}
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// EXPORTS //
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module.exports = incrsumabs2;
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