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author | Nao Pross <np@0hm.ch> | 2024-02-12 14:52:43 +0100 |
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committer | Nao Pross <np@0hm.ch> | 2024-02-12 14:52:43 +0100 |
commit | eda5bc26f44ee9a6f83dcf8c91f17296d7fc509d (patch) | |
tree | bc2efa38ff4e350f9a111ac87065cd7ae9a911c7 /src/Eigen/OrderingMethods | |
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-rw-r--r-- | src/Eigen/OrderingMethods | 70 |
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diff --git a/src/Eigen/OrderingMethods b/src/Eigen/OrderingMethods new file mode 100644 index 0000000..29691a6 --- /dev/null +++ b/src/Eigen/OrderingMethods @@ -0,0 +1,70 @@ +// This file is part of Eigen, a lightweight C++ template library +// for linear algebra. +// +// This Source Code Form is subject to the terms of the Mozilla +// Public License v. 2.0. If a copy of the MPL was not distributed +// with this file, You can obtain one at http://mozilla.org/MPL/2.0/. + +#ifndef EIGEN_ORDERINGMETHODS_MODULE_H +#define EIGEN_ORDERINGMETHODS_MODULE_H + +#include "SparseCore" + +#include "src/Core/util/DisableStupidWarnings.h" + +/** + * \defgroup OrderingMethods_Module OrderingMethods module + * + * This module is currently for internal use only + * + * It defines various built-in and external ordering methods for sparse matrices. + * They are typically used to reduce the number of elements during + * the sparse matrix decomposition (LLT, LU, QR). + * Precisely, in a preprocessing step, a permutation matrix P is computed using + * those ordering methods and applied to the columns of the matrix. + * Using for instance the sparse Cholesky decomposition, it is expected that + * the nonzeros elements in LLT(A*P) will be much smaller than that in LLT(A). + * + * + * Usage : + * \code + * #include <Eigen/OrderingMethods> + * \endcode + * + * A simple usage is as a template parameter in the sparse decomposition classes : + * + * \code + * SparseLU<MatrixType, COLAMDOrdering<int> > solver; + * \endcode + * + * \code + * SparseQR<MatrixType, COLAMDOrdering<int> > solver; + * \endcode + * + * It is possible as well to call directly a particular ordering method for your own purpose, + * \code + * AMDOrdering<int> ordering; + * PermutationMatrix<Dynamic, Dynamic, int> perm; + * SparseMatrix<double> A; + * //Fill the matrix ... + * + * ordering(A, perm); // Call AMD + * \endcode + * + * \note Some of these methods (like AMD or METIS), need the sparsity pattern + * of the input matrix to be symmetric. When the matrix is structurally unsymmetric, + * Eigen computes internally the pattern of \f$A^T*A\f$ before calling the method. + * If your matrix is already symmetric (at leat in structure), you can avoid that + * by calling the method with a SelfAdjointView type. + * + * \code + * // Call the ordering on the pattern of the lower triangular matrix A + * ordering(A.selfadjointView<Lower>(), perm); + * \endcode + */ + +#include "src/OrderingMethods/Amd.h" +#include "src/OrderingMethods/Ordering.h" +#include "src/Core/util/ReenableStupidWarnings.h" + +#endif // EIGEN_ORDERINGMETHODS_MODULE_H |