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* @license Apache-2.0
*
* Copyright (c) 2025 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';
/**
* Compute the scalar multiple of the first column of `K` where `K = (H - Z1)*(H - Z2)` for a 2-by-2 or a 3-by-3 matrix `H` and where `Z1 = z1*I`, `Z2 = z2*I`, `z1 = a + bi`, `z2 = c + di`, and `I` is the identity matrix.
*
* ## Notes
*
* - It is expected that either `sr1 = sr2` and `si1 + si2 = 0` or `si1 = si2 = 0` (i.e., they represent complex conjugate values).
* - This is useful for starting double implicit shift bulges in the QR algorithm.
* - `V` should have at least `N` indexed elements.
*
* @module @stdlib/lapack/base/dlaqr1
*
* @example
* var Float64Array = require( '@stdlib/array/float64' );
* var dlaqr1 = require( '@stdlib/lapack/base/dlaqr1' );
*
* var H = new Float64Array( [ 1.0, 3.0, 2.0, 2.0, 4.0, 6.0, 0.0, 5.0, 7.0 ] ); // => [ [ 1.0, 3.0, 2.0 ], [ 2.0, 4.0, 6.0 ], [ 0.0, 5.0, 7.0 ] ]
* var V = new Float64Array( 3 );
*
* var out = dlaqr1( 'row-major', 3, H, 3, 1.5, 0.0, 2.5, 0.0, V );
* // returns <Float64Array>[ ~1.93, ~0.57, ~2.86 ]
*/
// MODULES //
var join = require( 'path' ).join;
var tryRequire = require( '@stdlib/utils/try-require' );
var isError = require( '@stdlib/assert/is-error' );
var main = require( './main.js' );
// MAIN //
var dlaqr1;
var tmp = tryRequire( join( __dirname, './native.js' ) );
if ( isError( tmp ) ) {
dlaqr1 = main;
} else {
dlaqr1 = tmp;
}
// EXPORTS //
module.exports = dlaqr1;
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