1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 18 package org.apache.commons.math.linear; 19 20 21 /** 22 * An interface to classes that implement an algorithm to calculate the 23 * QR-decomposition of a real matrix. 24 * <p>This interface is based on the class with similar name from the 25 * <a href="http://math.nist.gov/javanumerics/jama/">JAMA</a> library, with the 26 * following changes:</p> 27 * <ul> 28 * <li>a {@link #getQT() getQT} method has been added,</li> 29 * <li>the <code>solve</code> and <code>isFullRank</code> methods have been replaced 30 * by a {@link #getSolver() getSolver} method and the equivalent methods provided by 31 * the returned {@link DecompositionSolver}.</li> 32 * </ul> 33 * 34 * @see <a href="http://mathworld.wolfram.com/QRDecomposition.html">MathWorld</a> 35 * @see <a href="http://en.wikipedia.org/wiki/QR_decomposition">Wikipedia</a> 36 * @version $Revision: 826627 $ $Date: 2009-10-19 12:27:47 +0200 (lun. 19 oct. 2009) $ 37 * @since 1.2 38 */ 39 public interface QRDecomposition { 40 41 /** 42 * Returns the matrix R of the decomposition. 43 * <p>R is an upper-triangular matrix</p> 44 * @return the R matrix 45 */ getR()46 RealMatrix getR(); 47 48 /** 49 * Returns the matrix Q of the decomposition. 50 * <p>Q is an orthogonal matrix</p> 51 * @return the Q matrix 52 */ getQ()53 RealMatrix getQ(); 54 55 /** 56 * Returns the transpose of the matrix Q of the decomposition. 57 * <p>Q is an orthogonal matrix</p> 58 * @return the Q matrix 59 */ getQT()60 RealMatrix getQT(); 61 62 /** 63 * Returns the Householder reflector vectors. 64 * <p>H is a lower trapezoidal matrix whose columns represent 65 * each successive Householder reflector vector. This matrix is used 66 * to compute Q.</p> 67 * @return a matrix containing the Householder reflector vectors 68 */ getH()69 RealMatrix getH(); 70 71 /** 72 * Get a solver for finding the A × X = B solution in least square sense. 73 * @return a solver 74 */ getSolver()75 DecompositionSolver getSolver(); 76 77 } 78