org.ejml.interfaces.decomposition.TridiagonalSimilarDecomposition Maven / Gradle / Ivy
/*
* Copyright (c) 2009-2014, Peter Abeles. All Rights Reserved.
*
* This file is part of Efficient Java Matrix Library (EJML).
*
* 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.
*/
package org.ejml.interfaces.decomposition;
import org.ejml.data.ReshapeMatrix64F;
/**
*
* Finds the decomposition of a matrix in the form of:
*
* A = O*T*OT
*
* where A is a symmetric m by m matrix, O is an orthogonal matrix, and T is a tridiagonal matrix.
*
*
* @author Peter Abeles
*/
public interface TridiagonalSimilarDecomposition
extends DecompositionInterface {
/**
* Extracts the tridiagonal matrix found in the decomposition.
*
* @param T If not null then the results will be stored here. Otherwise a new matrix will be created.
* @return The extracted T matrix.
*/
public MatrixType getT( MatrixType T );
/**
* An orthogonal matrix that has the following property: T = QTAQ
*
* @param Q If not null then the results will be stored here. Otherwise a new matrix will be created.
* @return The extracted Q matrix.
*/
public MatrixType getQ( MatrixType Q , boolean transposed );
/**
* Extracts the diagonal and off diagonal elements of the decomposed tridiagonal matrix.
* Since it is symmetric only one off diagonal array is returned.
*
* @param diag Diagonal elements. Modified.
* @param off off diagonal elements. Modified.
*/
public void getDiagonal( double []diag, double []off );
}