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Jeometry, a Mathematic and Geometry library for Java

There is a newer version: 1.0.5

package org.jeometry.math.decomposition;

import org.jeometry.Jeometry;
import org.jeometry.math.Matrix;
import org.jeometry.math.solver.Resolvable;

/**
 * This interface describes a Lower Upper (LU) decomposition.

 * 

 * Let A be a square matrix, the LU decomposition compute a lower triangular matrix L and an upper triangular matrix U such that: 

 * 

 * L×U = A

 * 

 * where × is the standard matrix product.
 * @author Julien Seinturier - COMEX S.A. - [email protected] - https://github.com/jorigin/jeometry
 * @version {@value Jeometry#version} b{@value Jeometry#BUILD}
 * @since 1.0.0
 */
public interface LUDecomposition extends Decomposition, Resolvable {

	/**
	 * The index of the triangular lower L matrix within the {@link Decomposition#getComponents() decomposition components}. 
	 */
	public static final int COMPONENT_L_INDEX = 0;
	
	/**
	 * The index of the triangular upper U matrix within the {@link Decomposition#getComponents() decomposition components}. 
	 */
	public static final int COMPONENT_U_INDEX = 1;
	
	/**
	 * Get the lower (L) triangular matrix from the decomposition.
	 * @return the lower triangular matrix from the decomposition.
	 * @see #getUpper()
	 */
	public Matrix getLower();
	
	/**
	 * Get the upper (U) triangular matrix from the decomposition.
	 * @return the upper (U) triangular matrix from the decomposition.
	 * @see #getLower()
	 */
	public Matrix getUpper();
	
	/**
	 * Get the permutation matrix (pivot) that has been used if the decomposition is formally:

	 * 

	 * A = PLU
	 * 

	 * @return the pivot that has been used.
	 */
	public Matrix getPivot();
}