63 lines
1.7 KiB
JavaScript
63 lines
1.7 KiB
JavaScript
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/**
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* @license Apache-2.0
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*
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* Copyright (c) 2020 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 Float64Array = require( '@stdlib/array/float64' );
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var addon = require( './dscal.native.js' );
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// MAIN //
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/**
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* Multiplies a vector `x` by a scalar `alpha`.
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*
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* @param {PositiveInteger} N - number of indexed elements
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* @param {number} alpha - scalar
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* @param {Float64Array} x - input array
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* @param {integer} stride - index increment
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* @param {NonNegativeInteger} offset - starting index
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* @returns {Float64Array} input array
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*
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* @example
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* var Float64Array = require( '@stdlib/array/float64' );
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*
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* var x = new Float64Array( [ 1.0, -2.0, 3.0, -4.0, 5.0, -6.0 ] );
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* var alpha = 5.0;
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*
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* dscal( 3, alpha, x, 1, x.length-3 );
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* // x => <Float64Array>[ 1.0, -2.0, 3.0, -20.0, 25.0, -30.0 ]
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*/
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function dscal( N, alpha, x, stride, offset ) {
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var view;
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if ( stride < 0 ) {
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stride *= -1;
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offset -= (N-1) * stride;
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}
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view = new Float64Array( x.buffer, x.byteOffset+(x.BYTES_PER_ELEMENT*offset), x.length-offset ); // eslint-disable-line max-len
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addon( N, alpha, view, stride );
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return x;
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}
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// EXPORTS //
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module.exports = dscal;
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