| Carlos Hernandez | 7faaa9f | 2014-08-05 17:53:32 -0700 | [diff] [blame] | 1 | // This file is part of Eigen, a lightweight C++ template library |
| 2 | // for linear algebra. |
| 3 | // |
| 4 | // Copyright (C) 2012 Désiré Nuentsa-Wakam <desire.nuentsa_wakam@inria.fr> |
| 5 | // |
| 6 | // This Source Code Form is subject to the terms of the Mozilla |
| 7 | // Public License v. 2.0. If a copy of the MPL was not distributed |
| 8 | // with this file, You can obtain one at http://mozilla.org/MPL/2.0/. |
| 9 | |
| 10 | /* This file is a modified version of heap_relax_snode.c file in SuperLU |
| 11 | * -- SuperLU routine (version 3.0) -- |
| 12 | * Univ. of California Berkeley, Xerox Palo Alto Research Center, |
| 13 | * and Lawrence Berkeley National Lab. |
| 14 | * October 15, 2003 |
| 15 | * |
| 16 | * Copyright (c) 1994 by Xerox Corporation. All rights reserved. |
| 17 | * |
| 18 | * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY |
| 19 | * EXPRESSED OR IMPLIED. ANY USE IS AT YOUR OWN RISK. |
| 20 | * |
| 21 | * Permission is hereby granted to use or copy this program for any |
| 22 | * purpose, provided the above notices are retained on all copies. |
| 23 | * Permission to modify the code and to distribute modified code is |
| 24 | * granted, provided the above notices are retained, and a notice that |
| 25 | * the code was modified is included with the above copyright notice. |
| 26 | */ |
| 27 | |
| 28 | #ifndef SPARSELU_RELAX_SNODE_H |
| 29 | #define SPARSELU_RELAX_SNODE_H |
| 30 | |
| 31 | namespace Eigen { |
| 32 | |
| 33 | namespace internal { |
| 34 | |
| 35 | /** |
| 36 | * \brief Identify the initial relaxed supernodes |
| 37 | * |
| 38 | * This routine is applied to a column elimination tree. |
| 39 | * It assumes that the matrix has been reordered according to the postorder of the etree |
| 40 | * \param n the number of columns |
| 41 | * \param et elimination tree |
| 42 | * \param relax_columns Maximum number of columns allowed in a relaxed snode |
| 43 | * \param descendants Number of descendants of each node in the etree |
| 44 | * \param relax_end last column in a supernode |
| 45 | */ |
| 46 | template <typename Scalar, typename Index> |
| 47 | void SparseLUImpl<Scalar,Index>::relax_snode (const Index n, IndexVector& et, const Index relax_columns, IndexVector& descendants, IndexVector& relax_end) |
| 48 | { |
| 49 | |
| 50 | // compute the number of descendants of each node in the etree |
| 51 | Index j, parent; |
| 52 | relax_end.setConstant(emptyIdxLU); |
| 53 | descendants.setZero(); |
| 54 | for (j = 0; j < n; j++) |
| 55 | { |
| 56 | parent = et(j); |
| 57 | if (parent != n) // not the dummy root |
| 58 | descendants(parent) += descendants(j) + 1; |
| 59 | } |
| 60 | // Identify the relaxed supernodes by postorder traversal of the etree |
| 61 | Index snode_start; // beginning of a snode |
| 62 | for (j = 0; j < n; ) |
| 63 | { |
| 64 | parent = et(j); |
| 65 | snode_start = j; |
| 66 | while ( parent != n && descendants(parent) < relax_columns ) |
| 67 | { |
| 68 | j = parent; |
| 69 | parent = et(j); |
| 70 | } |
| 71 | // Found a supernode in postordered etree, j is the last column |
| 72 | relax_end(snode_start) = j; // Record last column |
| 73 | j++; |
| 74 | // Search for a new leaf |
| 75 | while (descendants(j) != 0 && j < n) j++; |
| 76 | } // End postorder traversal of the etree |
| 77 | |
| 78 | } |
| 79 | |
| 80 | } // end namespace internal |
| 81 | |
| 82 | } // end namespace Eigen |
| 83 | #endif |