111 lines
2.4 KiB
JavaScript
111 lines
2.4 KiB
JavaScript
/**
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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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// VARIABLES //
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var M = 3;
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// MAIN //
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/**
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* Interchanges two double-precision floating-point vectors.
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*
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* @param {PositiveInteger} N - number of values to swap
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* @param {Float64Array} x - first input array
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* @param {integer} strideX - `x` stride length
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* @param {NonNegativeInteger} offsetX - starting `x` index
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* @param {Float64Array} y - second input array
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* @param {integer} strideY - `y` stride length
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* @param {NonNegativeInteger} offsetY - starting `y` index
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* @returns {Float64Array} `y`
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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 ] );
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* var y = new Float64Array( [ 6.0, 7.0, 8.0, 9.0, 10.0 ] );
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*
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* dswap( x.length, x, 1, 0, y, 1, 0 );
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* // x => <Float64Array>[ 6.0, 7.0, 8.0, 9.0, 10.0 ]
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* // y => <Float64Array>[ 1.0, 2.0, 3.0, 4.0, 5.0 ]
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*/
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function dswap( N, x, strideX, offsetX, y, strideY, offsetY ) {
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var tmp;
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var ix;
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var iy;
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var m;
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var i;
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if ( N <= 0 ) {
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return y;
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}
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ix = offsetX;
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iy = offsetY;
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// Use unrolled loops if both strides are equal to `1`...
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if ( strideX === 1 && strideY === 1 ) {
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m = N % M;
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// If we have a remainder, run a clean-up loop...
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if ( m > 0 ) {
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for ( i = 0; i < m; i++ ) {
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tmp = x[ ix ];
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x[ ix ] = y[ iy ];
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y[ iy ] = tmp;
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ix += strideX;
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iy += strideY;
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}
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}
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if ( N < M ) {
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return y;
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}
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for ( i = m; i < N; i += M ) {
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tmp = x[ ix ];
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x[ ix ] = y[ iy ];
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y[ iy ] = tmp;
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tmp = x[ ix+1 ];
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x[ ix+1 ] = y[ iy+1 ];
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y[ iy+1 ] = tmp;
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tmp = x[ ix+2 ];
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x[ ix+2 ] = y[ iy+2 ];
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y[ iy+2 ] = tmp;
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ix += M;
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iy += M;
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}
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return y;
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}
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for ( i = 0; i < N; i++ ) {
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tmp = x[ ix ];
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x[ ix ] = y[ iy ];
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y[ iy ] = tmp;
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ix += strideX;
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iy += strideY;
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}
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return y;
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}
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// EXPORTS //
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module.exports = dswap;
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