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Diffstat (limited to 'third_party/eigen3/Eigen/src/SparseLU/SparseLU_heap_relax_snode.h')
| -rw-r--r-- | third_party/eigen3/Eigen/src/SparseLU/SparseLU_heap_relax_snode.h | 127 |
1 files changed, 127 insertions, 0 deletions
diff --git a/third_party/eigen3/Eigen/src/SparseLU/SparseLU_heap_relax_snode.h b/third_party/eigen3/Eigen/src/SparseLU/SparseLU_heap_relax_snode.h new file mode 100644 index 0000000000..7a4e4305aa --- /dev/null +++ b/third_party/eigen3/Eigen/src/SparseLU/SparseLU_heap_relax_snode.h @@ -0,0 +1,127 @@ +// 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. + */ + +#ifndef SPARSELU_HEAP_RELAX_SNODE_H +#define SPARSELU_HEAP_RELAX_SNODE_H + +namespace Eigen { +namespace internal { + +/** + * \brief Identify the initial relaxed supernodes + * + * This routine applied to a symmetric 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 Index> +void SparseLUImpl<Scalar,Index>::heap_relax_snode (const Index n, IndexVector& et, const Index relax_columns, IndexVector& descendants, IndexVector& relax_end) +{ + + // The etree may not be postordered, but its heap ordered + IndexVector post; + internal::treePostorder(n, et, post); // Post order etree + IndexVector inv_post(n+1); + Index i; + for (i = 0; i < n+1; ++i) inv_post(post(i)) = i; // inv_post = post.inverse()??? + + // Renumber etree in postorder + IndexVector iwork(n); + IndexVector et_save(n+1); + for (i = 0; i < n; ++i) + { + iwork(post(i)) = post(et(i)); + } + et_save = et; // Save the original etree + et = iwork; + + // compute the number of descendants of each node in the etree + relax_end.setConstant(emptyIdxLU); + Index j, parent; + descendants.setZero(); + for (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 + Index k; + Index nsuper_et_post = 0; // Number of relaxed snodes in postordered etree + Index nsuper_et = 0; // Number of relaxed snodes in the original etree + Index l; + for (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 + ++nsuper_et_post; + k = n; + for (i = snode_start; i <= j; ++i) + k = (std::min)(k, inv_post(i)); + l = inv_post(j); + if ( (l - k) == (j - snode_start) ) // Same number of columns in the snode + { + // This is also a supernode in the original etree + relax_end(k) = l; // Record last column + ++nsuper_et; + } + else + { + for (i = snode_start; i <= j; ++i) + { + l = inv_post(i); + if (descendants(i) == 0) + { + relax_end(l) = l; + ++nsuper_et; + } + } + } + j++; + // Search for a new leaf + while (descendants(j) != 0 && j < n) j++; + } // End postorder traversal of the etree + + // Recover the original etree + et = et_save; +} + +} // end namespace internal + +} // end namespace Eigen +#endif // SPARSELU_HEAP_RELAX_SNODE_H |