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 StorageIndex>
46 void SparseLUImpl<Scalar,StorageIndex>::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(StorageIndex(n), et, post); // Post order etree
52  IndexVector inv_post(n+1);
53  for (StorageIndex i = 0; i < n+1; ++i) inv_post(post(i)) = i; // inv_post = post.inverse()???
54 
55  // Renumber etree in postorder
56  IndexVector iwork(n);
57  IndexVector et_save(n+1);
58  for (Index i = 0; i < n; ++i)
59  {
60  iwork(post(i)) = post(et(i));
61  }
62  et_save = et; // Save the original etree
63  et = iwork;
64 
65  // compute the number of descendants of each node in the etree
66  relax_end.setConstant(emptyIdxLU);
67  Index j, parent;
68  descendants.setZero();
69  for (j = 0; j < n; j++)
70  {
71  parent = et(j);
72  if (parent != n) // not the dummy root
73  descendants(parent) += descendants(j) + 1;
74  }
75  // Identify the relaxed supernodes by postorder traversal of the etree
76  Index snode_start; // beginning of a snode
77  StorageIndex k;
78  Index nsuper_et_post = 0; // Number of relaxed snodes in postordered etree
79  Index nsuper_et = 0; // Number of relaxed snodes in the original etree
80  StorageIndex l;
81  for (j = 0; j < n; )
82  {
83  parent = et(j);
84  snode_start = j;
85  while ( parent != n && descendants(parent) < relax_columns )
86  {
87  j = parent;
88  parent = et(j);
89  }
90  // Found a supernode in postordered etree, j is the last column
91  ++nsuper_et_post;
92  k = StorageIndex(n);
93  for (Index i = snode_start; i <= j; ++i)
94  k = (std::min)(k, inv_post(i));
95  l = inv_post(j);
96  if ( (l - k) == (j - snode_start) ) // Same number of columns in the snode
97  {
98  // This is also a supernode in the original etree
99  relax_end(k) = l; // Record last column
100  ++nsuper_et;
101  }
102  else
103  {
104  for (Index i = snode_start; i <= j; ++i)
105  {
106  l = inv_post(i);
107  if (descendants(i) == 0)
108  {
109  relax_end(l) = l;
110  ++nsuper_et;
111  }
112  }
113  }
114  j++;
115  // Search for a new leaf
116  while (descendants(j) != 0 && j < n) j++;
117  } // End postorder traversal of the etree
118 
119  // Recover the original etree
120  et = et_save;
121 }
122 
123 } // end namespace internal
124 
125 } // end namespace Eigen
126 #endif // SPARSELU_HEAP_RELAX_SNODE_H
EIGEN_DEVICE_FUNC Derived & setZero(Index size)
#define min(a, b)
Definition: datatypes.h:19
int n
Namespace containing all symbols from the Eigen library.
Definition: jet.h:637
void heap_relax_snode(const Index n, IndexVector &et, const Index relax_columns, IndexVector &descendants, IndexVector &relax_end)
Identify the initial relaxed supernodes.
static const Line3 l(Rot3(), 1, 1)
EIGEN_DEFAULT_DENSE_INDEX_TYPE Index
The Index type as used for the API.
Definition: Meta.h:33
EIGEN_DEVICE_FUNC Derived & setConstant(Index size, const Scalar &val)
void treePostorder(typename IndexVector::Scalar n, IndexVector &parent, IndexVector &post)
Post order a tree.
std::ptrdiff_t j


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autogenerated on Sat May 8 2021 02:44:24