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Diffstat (limited to 'src/main/java/org/apache/commons/math/linear/FieldLUDecomposition.java')
-rw-r--r-- | src/main/java/org/apache/commons/math/linear/FieldLUDecomposition.java | 94 |
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diff --git a/src/main/java/org/apache/commons/math/linear/FieldLUDecomposition.java b/src/main/java/org/apache/commons/math/linear/FieldLUDecomposition.java new file mode 100644 index 0000000..cbdbadd --- /dev/null +++ b/src/main/java/org/apache/commons/math/linear/FieldLUDecomposition.java @@ -0,0 +1,94 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You 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.apache.commons.math.linear; + +import org.apache.commons.math.FieldElement; + +/** + * An interface to classes that implement an algorithm to calculate the + * LU-decomposition of a real matrix. + * <p>The LU-decomposition of matrix A is a set of three matrices: P, L and U + * such that P×A = L×U. P is a rows permutation matrix that is used + * to rearrange the rows of A before so that it can be decomposed. L is a lower + * triangular matrix with unit diagonal terms and U is an upper triangular matrix.</p> + * <p>This interface is based on the class with similar name from the + * <a href="http://math.nist.gov/javanumerics/jama/">JAMA</a> library.</p> + * <ul> + * <li>a {@link #getP() getP} method has been added,</li> + * <li>the <code>det</code> method has been renamed as {@link #getDeterminant() + * getDeterminant},</li> + * <li>the <code>getDoublePivot</code> method has been removed (but the int based + * {@link #getPivot() getPivot} method has been kept),</li> + * <li>the <code>solve</code> and <code>isNonSingular</code> methods have been replaced + * by a {@link #getSolver() getSolver} method and the equivalent methods provided by + * the returned {@link DecompositionSolver}.</li> + * </ul> + * + * @param <T> the type of the field elements + * @see <a href="http://mathworld.wolfram.com/LUDecomposition.html">MathWorld</a> + * @see <a href="http://en.wikipedia.org/wiki/LU_decomposition">Wikipedia</a> + * @version $Revision: 826627 $ $Date: 2009-10-19 12:27:47 +0200 (lun. 19 oct. 2009) $ + * @since 2.0 + */ +public interface FieldLUDecomposition<T extends FieldElement<T>> { + + /** + * Returns the matrix L of the decomposition. + * <p>L is an lower-triangular matrix</p> + * @return the L matrix (or null if decomposed matrix is singular) + */ + FieldMatrix<T> getL(); + + /** + * Returns the matrix U of the decomposition. + * <p>U is an upper-triangular matrix</p> + * @return the U matrix (or null if decomposed matrix is singular) + */ + FieldMatrix<T> getU(); + + /** + * Returns the P rows permutation matrix. + * <p>P is a sparse matrix with exactly one element set to 1.0 in + * each row and each column, all other elements being set to 0.0.</p> + * <p>The positions of the 1 elements are given by the {@link #getPivot() + * pivot permutation vector}.</p> + * @return the P rows permutation matrix (or null if decomposed matrix is singular) + * @see #getPivot() + */ + FieldMatrix<T> getP(); + + /** + * Returns the pivot permutation vector. + * @return the pivot permutation vector + * @see #getP() + */ + int[] getPivot(); + + /** + * Return the determinant of the matrix + * @return determinant of the matrix + */ + T getDeterminant(); + + /** + * Get a solver for finding the A × X = B solution in exact linear sense. + * @return a solver + */ + FieldDecompositionSolver<T> getSolver(); + +} |