| // This file is part of Eigen, a lightweight C++ template library | |
| // for linear algebra. | |
| // | |
| // Copyright (C) 2012 Désiré Nuentsa-Wakam <desire.nuentsa_wakam@inria.fr> | |
| // | |
| // 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/. | |
| /* This file is a modified version of heap_relax_snode.c file in SuperLU | |
| * -- SuperLU routine (version 3.0) -- | |
| * Univ. of California Berkeley, Xerox Palo Alto Research Center, | |
| * and Lawrence Berkeley National Lab. | |
| * October 15, 2003 | |
| * | |
| * Copyright (c) 1994 by Xerox Corporation. All rights reserved. | |
| * | |
| * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY | |
| * EXPRESSED OR IMPLIED. ANY USE IS AT YOUR OWN RISK. | |
| * | |
| * Permission is hereby granted to use or copy this program for any | |
| * purpose, provided the above notices are retained on all copies. | |
| * Permission to modify the code and to distribute modified code is | |
| * granted, provided the above notices are retained, and a notice that | |
| * the code was modified is included with the above copyright notice. | |
| */ | |
| namespace Eigen { | |
| namespace internal { | |
| /** | |
| * \brief Identify the initial relaxed supernodes | |
| * | |
| * This routine is applied to a column elimination tree. | |
| * It assumes that the matrix has been reordered according to the postorder of the etree | |
| * \param n the number of columns | |
| * \param et elimination tree | |
| * \param relax_columns Maximum number of columns allowed in a relaxed snode | |
| * \param descendants Number of descendants of each node in the etree | |
| * \param relax_end last column in a supernode | |
| */ | |
| template <typename Scalar, typename StorageIndex> | |
| void SparseLUImpl<Scalar,StorageIndex>::relax_snode (const Index n, IndexVector& et, const Index relax_columns, IndexVector& descendants, IndexVector& relax_end) | |
| { | |
| // compute the number of descendants of each node in the etree | |
| Index parent; | |
| relax_end.setConstant(emptyIdxLU); | |
| descendants.setZero(); | |
| for (Index j = 0; j < n; j++) | |
| { | |
| parent = et(j); | |
| if (parent != n) // not the dummy root | |
| descendants(parent) += descendants(j) + 1; | |
| } | |
| // Identify the relaxed supernodes by postorder traversal of the etree | |
| Index snode_start; // beginning of a snode | |
| for (Index j = 0; j < n; ) | |
| { | |
| parent = et(j); | |
| snode_start = j; | |
| while ( parent != n && descendants(parent) < relax_columns ) | |
| { | |
| j = parent; | |
| parent = et(j); | |
| } | |
| // Found a supernode in postordered etree, j is the last column | |
| relax_end(snode_start) = StorageIndex(j); // Record last column | |
| j++; | |
| // Search for a new leaf | |
| while (descendants(j) != 0 && j < n) j++; | |
| } // End postorder traversal of the etree | |
| } | |
| } // end namespace internal | |
| } // end namespace Eigen | |