SparseLU_heap_relax_snode.h
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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_HEAP_RELAX_SNODE_H
29 #define SPARSELU_HEAP_RELAX_SNODE_H
30 
31 namespace Eigen {
32 namespace internal {
33 
45 template <typename Scalar, typename Index>
46 void SparseLUImpl<Scalar,Index>::heap_relax_snode (const Index n, IndexVector& et, const Index relax_columns, IndexVector& descendants, IndexVector& relax_end)
47 {
48 
49  // The etree may not be postordered, but its heap ordered
50  IndexVector post;
51  internal::treePostorder(n, et, post); // Post order etree
52  IndexVector inv_post(n+1);
53  Index i;
54  for (i = 0; i < n+1; ++i) inv_post(post(i)) = i; // inv_post = post.inverse()???
55 
56  // Renumber etree in postorder
57  IndexVector iwork(n);
58  IndexVector et_save(n+1);
59  for (i = 0; i < n; ++i)
60  {
61  iwork(post(i)) = post(et(i));
62  }
63  et_save = et; // Save the original etree
64  et = iwork;
65 
66  // compute the number of descendants of each node in the etree
67  relax_end.setConstant(emptyIdxLU);
68  Index j, parent;
69  descendants.setZero();
70  for (j = 0; j < n; j++)
71  {
72  parent = et(j);
73  if (parent != n) // not the dummy root
74  descendants(parent) += descendants(j) + 1;
75  }
76  // Identify the relaxed supernodes by postorder traversal of the etree
77  Index snode_start; // beginning of a snode
78  Index k;
79  Index nsuper_et_post = 0; // Number of relaxed snodes in postordered etree
80  Index nsuper_et = 0; // Number of relaxed snodes in the original etree
81  Index l;
82  for (j = 0; j < n; )
83  {
84  parent = et(j);
85  snode_start = j;
86  while ( parent != n && descendants(parent) < relax_columns )
87  {
88  j = parent;
89  parent = et(j);
90  }
91  // Found a supernode in postordered etree, j is the last column
92  ++nsuper_et_post;
93  k = n;
94  for (i = snode_start; i <= j; ++i)
95  k = (std::min)(k, inv_post(i));
96  l = inv_post(j);
97  if ( (l - k) == (j - snode_start) ) // Same number of columns in the snode
98  {
99  // This is also a supernode in the original etree
100  relax_end(k) = l; // Record last column
101  ++nsuper_et;
102  }
103  else
104  {
105  for (i = snode_start; i <= j; ++i)
106  {
107  l = inv_post(i);
108  if (descendants(i) == 0)
109  {
110  relax_end(l) = l;
111  ++nsuper_et;
112  }
113  }
114  }
115  j++;
116  // Search for a new leaf
117  while (descendants(j) != 0 && j < n) j++;
118  } // End postorder traversal of the etree
119 
120  // Recover the original etree
121  et = et_save;
122 }
123 
124 } // end namespace internal
125 
126 } // end namespace Eigen
127 #endif // SPARSELU_HEAP_RELAX_SNODE_H
iterative scaling algorithm to equilibrate rows and column norms in matrices
Definition: matrix.hpp:471
Derived & setZero(Index size)
Derived & setConstant(Index size, const Scalar &value)
void treePostorder(Index n, IndexVector &parent, IndexVector &post)
Post order a tree.
void heap_relax_snode(const Index n, IndexVector &et, const Index relax_columns, IndexVector &descendants, IndexVector &relax_end)
Identify the initial relaxed supernodes.


acado
Author(s): Milan Vukov, Rien Quirynen
autogenerated on Mon Jun 10 2019 12:35:08