[136] | 1 | // This file is part of Eigen, a lightweight C++ template library
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| 2 | // for linear algebra.
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| 3 | //
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| 4 | // Copyright (C) 2012 Désiré Nuentsa-Wakam <desire.nuentsa_wakam@inria.fr>
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| 5 | //
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| 6 | // This Source Code Form is subject to the terms of the Mozilla
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| 7 | // Public License v. 2.0. If a copy of the MPL was not distributed
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| 8 | // with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
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| 9 |
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| 10 | /* This file is a modified version of heap_relax_snode.c file in SuperLU
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| 11 | * -- SuperLU routine (version 3.0) --
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| 12 | * Univ. of California Berkeley, Xerox Palo Alto Research Center,
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| 13 | * and Lawrence Berkeley National Lab.
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| 14 | * October 15, 2003
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| 15 | *
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| 16 | * Copyright (c) 1994 by Xerox Corporation. All rights reserved.
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| 17 | *
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| 18 | * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY
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| 19 | * EXPRESSED OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
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| 20 | *
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| 21 | * Permission is hereby granted to use or copy this program for any
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| 22 | * purpose, provided the above notices are retained on all copies.
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| 23 | * Permission to modify the code and to distribute modified code is
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| 24 | * granted, provided the above notices are retained, and a notice that
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| 25 | * the code was modified is included with the above copyright notice.
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| 26 | */
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| 27 |
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| 28 | #ifndef SPARSELU_RELAX_SNODE_H
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| 29 | #define SPARSELU_RELAX_SNODE_H
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| 30 |
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| 31 | namespace Eigen {
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| 32 |
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| 33 | namespace internal {
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| 34 |
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| 35 | /**
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| 36 | * \brief Identify the initial relaxed supernodes
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| 37 | *
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| 38 | * This routine is applied to a column elimination tree.
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| 39 | * It assumes that the matrix has been reordered according to the postorder of the etree
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| 40 | * \param n the number of columns
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| 41 | * \param et elimination tree
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| 42 | * \param relax_columns Maximum number of columns allowed in a relaxed snode
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| 43 | * \param descendants Number of descendants of each node in the etree
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| 44 | * \param relax_end last column in a supernode
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| 45 | */
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| 46 | template <typename Scalar, typename Index>
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| 47 | void SparseLUImpl<Scalar,Index>::relax_snode (const Index n, IndexVector& et, const Index relax_columns, IndexVector& descendants, IndexVector& relax_end)
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| 48 | {
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| 49 |
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| 50 | // compute the number of descendants of each node in the etree
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| 51 | Index j, parent;
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| 52 | relax_end.setConstant(emptyIdxLU);
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| 53 | descendants.setZero();
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| 54 | for (j = 0; j < n; j++)
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| 55 | {
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| 56 | parent = et(j);
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| 57 | if (parent != n) // not the dummy root
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| 58 | descendants(parent) += descendants(j) + 1;
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| 59 | }
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| 60 | // Identify the relaxed supernodes by postorder traversal of the etree
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| 61 | Index snode_start; // beginning of a snode
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| 62 | for (j = 0; j < n; )
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| 63 | {
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| 64 | parent = et(j);
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| 65 | snode_start = j;
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| 66 | while ( parent != n && descendants(parent) < relax_columns )
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| 67 | {
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| 68 | j = parent;
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| 69 | parent = et(j);
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| 70 | }
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| 71 | // Found a supernode in postordered etree, j is the last column
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| 72 | relax_end(snode_start) = j; // Record last column
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| 73 | j++;
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| 74 | // Search for a new leaf
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| 75 | while (descendants(j) != 0 && j < n) j++;
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| 76 | } // End postorder traversal of the etree
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| 77 |
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| 78 | }
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| 79 |
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| 80 | } // end namespace internal
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| 81 |
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| 82 | } // end namespace Eigen
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| 83 | #endif
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