| Brian Silverman | 72890c2 | 2015-09-19 14:37:37 -0400 | [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 | /* |
| 11 | |
| 12 | * NOTE: This file is the modified version of [s,d,c,z]pruneL.c file in SuperLU |
| 13 | |
| 14 | * -- SuperLU routine (version 2.0) -- |
| 15 | * Univ. of California Berkeley, Xerox Palo Alto Research Center, |
| 16 | * and Lawrence Berkeley National Lab. |
| 17 | * November 15, 1997 |
| 18 | * |
| 19 | * Copyright (c) 1994 by Xerox Corporation. All rights reserved. |
| 20 | * |
| 21 | * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY |
| 22 | * EXPRESSED OR IMPLIED. ANY USE IS AT YOUR OWN RISK. |
| 23 | * |
| 24 | * Permission is hereby granted to use or copy this program for any |
| 25 | * purpose, provided the above notices are retained on all copies. |
| 26 | * Permission to modify the code and to distribute modified code is |
| 27 | * granted, provided the above notices are retained, and a notice that |
| 28 | * the code was modified is included with the above copyright notice. |
| 29 | */ |
| 30 | #ifndef SPARSELU_PRUNEL_H |
| 31 | #define SPARSELU_PRUNEL_H |
| 32 | |
| 33 | namespace Eigen { |
| 34 | namespace internal { |
| 35 | |
| 36 | /** |
| 37 | * \brief Prunes the L-structure. |
| 38 | * |
| 39 | * It prunes the L-structure of supernodes whose L-structure contains the current pivot row "pivrow" |
| 40 | * |
| 41 | * |
| 42 | * \param jcol The current column of L |
| 43 | * \param[in] perm_r Row permutation |
| 44 | * \param[out] pivrow The pivot row |
| 45 | * \param nseg Number of segments |
| 46 | * \param segrep |
| 47 | * \param repfnz |
| 48 | * \param[out] xprune |
| 49 | * \param glu Global LU data |
| 50 | * |
| 51 | */ |
| 52 | template <typename Scalar, typename Index> |
| 53 | void SparseLUImpl<Scalar,Index>::pruneL(const Index jcol, const IndexVector& perm_r, const Index pivrow, const Index nseg, const IndexVector& segrep, BlockIndexVector repfnz, IndexVector& xprune, GlobalLU_t& glu) |
| 54 | { |
| 55 | // For each supernode-rep irep in U(*,j] |
| 56 | Index jsupno = glu.supno(jcol); |
| 57 | Index i,irep,irep1; |
| 58 | bool movnum, do_prune = false; |
| 59 | Index kmin = 0, kmax = 0, minloc, maxloc,krow; |
| 60 | for (i = 0; i < nseg; i++) |
| 61 | { |
| 62 | irep = segrep(i); |
| 63 | irep1 = irep + 1; |
| 64 | do_prune = false; |
| 65 | |
| 66 | // Don't prune with a zero U-segment |
| 67 | if (repfnz(irep) == emptyIdxLU) continue; |
| 68 | |
| 69 | // If a snode overlaps with the next panel, then the U-segment |
| 70 | // is fragmented into two parts -- irep and irep1. We should let |
| 71 | // pruning occur at the rep-column in irep1s snode. |
| 72 | if (glu.supno(irep) == glu.supno(irep1) ) continue; // don't prune |
| 73 | |
| 74 | // If it has not been pruned & it has a nonz in row L(pivrow,i) |
| 75 | if (glu.supno(irep) != jsupno ) |
| 76 | { |
| 77 | if ( xprune (irep) >= glu.xlsub(irep1) ) |
| 78 | { |
| 79 | kmin = glu.xlsub(irep); |
| 80 | kmax = glu.xlsub(irep1) - 1; |
| 81 | for (krow = kmin; krow <= kmax; krow++) |
| 82 | { |
| 83 | if (glu.lsub(krow) == pivrow) |
| 84 | { |
| 85 | do_prune = true; |
| 86 | break; |
| 87 | } |
| 88 | } |
| 89 | } |
| 90 | |
| 91 | if (do_prune) |
| 92 | { |
| 93 | // do a quicksort-type partition |
| 94 | // movnum=true means that the num values have to be exchanged |
| 95 | movnum = false; |
| 96 | if (irep == glu.xsup(glu.supno(irep)) ) // Snode of size 1 |
| 97 | movnum = true; |
| 98 | |
| 99 | while (kmin <= kmax) |
| 100 | { |
| 101 | if (perm_r(glu.lsub(kmax)) == emptyIdxLU) |
| 102 | kmax--; |
| 103 | else if ( perm_r(glu.lsub(kmin)) != emptyIdxLU) |
| 104 | kmin++; |
| 105 | else |
| 106 | { |
| 107 | // kmin below pivrow (not yet pivoted), and kmax |
| 108 | // above pivrow: interchange the two suscripts |
| 109 | std::swap(glu.lsub(kmin), glu.lsub(kmax)); |
| 110 | |
| 111 | // If the supernode has only one column, then we |
| 112 | // only keep one set of subscripts. For any subscript |
| 113 | // intercnahge performed, similar interchange must be |
| 114 | // done on the numerical values. |
| 115 | if (movnum) |
| 116 | { |
| 117 | minloc = glu.xlusup(irep) + ( kmin - glu.xlsub(irep) ); |
| 118 | maxloc = glu.xlusup(irep) + ( kmax - glu.xlsub(irep) ); |
| 119 | std::swap(glu.lusup(minloc), glu.lusup(maxloc)); |
| 120 | } |
| 121 | kmin++; |
| 122 | kmax--; |
| 123 | } |
| 124 | } // end while |
| 125 | |
| 126 | xprune(irep) = kmin; //Pruning |
| 127 | } // end if do_prune |
| 128 | } // end pruning |
| 129 | } // End for each U-segment |
| 130 | } |
| 131 | |
| 132 | } // end namespace internal |
| 133 | } // end namespace Eigen |
| 134 | |
| 135 | #endif // SPARSELU_PRUNEL_H |