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Diffstat (limited to 'extern/Eigen3/Eigen/OrderingMethods')
-rw-r--r-- | extern/Eigen3/Eigen/OrderingMethods | 51 |
1 files changed, 47 insertions, 4 deletions
diff --git a/extern/Eigen3/Eigen/OrderingMethods b/extern/Eigen3/Eigen/OrderingMethods index 1e2d87452e5..7c0f1fffff6 100644 --- a/extern/Eigen3/Eigen/OrderingMethods +++ b/extern/Eigen3/Eigen/OrderingMethods @@ -5,19 +5,62 @@ #include "src/Core/util/DisableStupidWarnings.h" -/** \ingroup Sparse_modules +/** * \defgroup OrderingMethods_Module OrderingMethods module * - * This module is currently for internal use only. - * - * + * 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 */ +#ifndef EIGEN_MPL2_ONLY #include "src/OrderingMethods/Amd.h" +#endif +#include "src/OrderingMethods/Ordering.h" #include "src/Core/util/ReenableStupidWarnings.h" #endif // EIGEN_ORDERINGMETHODS_MODULE_H |