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