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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';
// MODULES //
var base = require( './base.js' );
// MAIN //
/**
* Estimates the one-norm of a square matrix `A`, using alternative indexing semantics and reverse communication for evaluating matrix-vector products.
*
* ## Notes
*
* The reverse communication takes place using `KASE`. The single-element in `KASE` may have the following values:
*
* - `0`: estimation is complete
* - `1`: caller must compute `A * X` and store the result back in `X`
* - `2`: caller must compute `A^T * X` (transpose) and store the result back in `X`
*
* `V` is over written by `A * W` where `EST` contains `norm( A ) / norm( W )`. (W is not returned)
*
* `ISAVE` has the following three elements:
*
* - the first indexed element of `ISAVE` is used to determine the control flow for the algorithm.
* - the second indexed element of `ISAVE` holds the index of the largest absolute value in `X`
* - the third indexed element of `ISAVE` counts the number of refinement iterations in the algorithm.
*
* @param {PositiveInteger} N - number of rows/columns in `A`
* @param {Float64Array} V - workspace array having `N` indexed elements, used internally to store intermediate vectors
* @param {integer} strideV - stride length for `V`
* @param {NonNegativeInteger} offsetV - starting index for `V`
* @param {Float64Array} X - input/output vector having `N` indexed elements, contains the current or next matrix-vector product
* @param {integer} strideX - stride length for `X`
* @param {NonNegativeInteger} offsetX - starting index for `X`
* @param {Int32Array} ISGN - integer array having `N` indexed elements, stores the sign of each element in `X` during iterations
* @param {integer} strideISGN - stride length for `ISGN`
* @param {NonNegativeInteger} offsetISGN - starting index for `ISGN`
* @param {Float64Array} EST - single-element array, on output, contains the estimated one-norm of the matrix `A`
* @param {NonNegativeInteger} offsetEST - starting index for `EST`
* @param {Int32Array} KASE - single-element array that controls the reverse communication.
* @param {NonNegativeInteger} offsetKASE - starting index for `KASE`
* @param {Int32Array} ISAVE - integer array having 3 indexed elements, used internally to maintain state across multiple calls
* @param {integer} strideISAVE - stride length for `ISAVE`
* @param {NonNegativeInteger} offsetISAVE - starting index for `ISAVE`
* @returns {void}
*
* @example
* var Int32Array = require( '@stdlib/array/int32' );
* var Float64Array = require( '@stdlib/array/float64' );
*
* var V = new Float64Array( [ 5.0, 3.0, 1.0, 5.0 ] );
* var X = new Float64Array( [ 1.0, 2.0, 3.0, 4.0 ] );
* var ISGN = new Int32Array( [ 1, 1, 1, 1 ] );
* var EST = new Float64Array( [ 10 ] );
* var KASE = new Int32Array( [ 1 ] )
* var ISAVE = new Int32Array( [ 2, 3, 1 ] );
*
* dlacn2( 4, V, 1, 0, X, 1, 0, ISGN, 1, 0, EST, 0, KASE, 0, ISAVE, 1, 0 );
* // X => <Float64Array>[ 0.0, 0.0, 0.0, 1.0 ]
* // V => <Float64Array>[ 5.0, 3.0, 1.0, 5.0 ]
* // EST => <Float64Array>[ 10.0 ]
* // KASE => <Int32Array>[ 1 ]
*/
function dlacn2( N, V, strideV, offsetV, X, strideX, offsetX, ISGN, strideISGN, offsetISGN, EST, offsetEST, KASE, offsetKASE, ISAVE, strideISAVE, offsetISAVE ) { // eslint-disable-line max-len, max-params
return base( N, V, strideV, offsetV, X, strideX, offsetX, ISGN, strideISGN, offsetISGN, EST, offsetEST, KASE, offsetKASE, ISAVE, strideISAVE, offsetISAVE ); // eslint-disable-line max-len
}
// EXPORTS //
module.exports = dlacn2;
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