[136] | 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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