1 // This file is part of Eigen, a lightweight C++ template library 2 // for linear algebra. 3 // 4 // This Source Code Form is subject to the terms of the Mozilla 5 // Public License v. 2.0. If a copy of the MPL was not distributed 6 // with this file, You can obtain one at http://mozilla.org/MPL/2.0/. 7 8 #ifndef EIGEN_ORDERINGMETHODS_MODULE_H 9 #define EIGEN_ORDERINGMETHODS_MODULE_H 10 11 #include "SparseCore" 12 13 #include "src/Core/util/DisableStupidWarnings.h" 14 15 /** 16 * \defgroup OrderingMethods_Module OrderingMethods module 17 * 18 * This module is currently for internal use only 19 * 20 * It defines various built-in and external ordering methods for sparse matrices. 21 * They are typically used to reduce the number of elements during 22 * the sparse matrix decomposition (LLT, LU, QR). 23 * Precisely, in a preprocessing step, a permutation matrix P is computed using 24 * those ordering methods and applied to the columns of the matrix. 25 * Using for instance the sparse Cholesky decomposition, it is expected that 26 * the nonzeros elements in LLT(A*P) will be much smaller than that in LLT(A). 27 * 28 * 29 * Usage : 30 * \code 31 * #include <Eigen/OrderingMethods> 32 * \endcode 33 * 34 * A simple usage is as a template parameter in the sparse decomposition classes : 35 * 36 * \code 37 * SparseLU<MatrixType, COLAMDOrdering<int> > solver; 38 * \endcode 39 * 40 * \code 41 * SparseQR<MatrixType, COLAMDOrdering<int> > solver; 42 * \endcode 43 * 44 * It is possible as well to call directly a particular ordering method for your own purpose, 45 * \code 46 * AMDOrdering<int> ordering; 47 * PermutationMatrix<Dynamic, Dynamic, int> perm; 48 * SparseMatrix<double> A; 49 * //Fill the matrix ... 50 * 51 * ordering(A, perm); // Call AMD 52 * \endcode 53 * 54 * \note Some of these methods (like AMD or METIS), need the sparsity pattern 55 * of the input matrix to be symmetric. When the matrix is structurally unsymmetric, 56 * Eigen computes internally the pattern of \f$A^T*A\f$ before calling the method. 57 * If your matrix is already symmetric (at leat in structure), you can avoid that 58 * by calling the method with a SelfAdjointView type. 59 * 60 * \code 61 * // Call the ordering on the pattern of the lower triangular matrix A 62 * ordering(A.selfadjointView<Lower>(), perm); 63 * \endcode 64 */ 65 66 #ifndef EIGEN_MPL2_ONLY 67 #include "src/OrderingMethods/Amd.h" 68 #endif 69 70 #include "src/OrderingMethods/Ordering.h" 71 #include "src/Core/util/ReenableStupidWarnings.h" 72 73 #endif // EIGEN_ORDERINGMETHODS_MODULE_H 74
