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 * Copyright 1997-2025 Optimatika
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 * of this software and associated documentation files (the "Software"), to deal
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 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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package org.ojalgo.matrix.decomposition;

import org.ojalgo.array.ArrayR064;
import org.ojalgo.array.BasicArray;
import org.ojalgo.matrix.store.MatrixStore;
import org.ojalgo.matrix.store.R064Store;
import org.ojalgo.matrix.store.TransformableRegion;
import org.ojalgo.structure.Access2D;

/**
 * Computes Q while decomposing.
 *
 * @author apete
 */
class SimultaneousTridiagonal extends DenseTridiagonal<Double> {

    private BasicArray<Double> myDiagD;
    private BasicArray<Double> myDiagE;

    SimultaneousTridiagonal() {
        super(R064Store.FACTORY);
    }

    public boolean decompose(final Access2D.Collectable<Double, ? super TransformableRegion<Double>> matrix) {

        this.setInPlace(matrix);

        final int size = this.getMinDim();

        if ((myDiagD == null) || (myDiagD.count() == size)) {
            myDiagD = ArrayR064.make(size);
            myDiagE = ArrayR064.make(size);
        }

        this.getInPlace().tred2(myDiagD, myDiagE, true);

        return this.computed(true);
    }

    @Override
    protected void supplyDiagonalTo(final double[] d, final double[] e) {
        myDiagD.supplyTo(d);
        myDiagE.supplyTo(e);
    }

    @Override
    MatrixStore<Double> makeD() {
        return this.makeDiagonal(myDiagD).superdiagonal(myDiagE).subdiagonal(myDiagE).get();
    }

    @Override
    DecompositionStore<Double> makeQ() {
        return this.getInPlace();
    }

}
