136 lines
4.4 KiB
C++
136 lines
4.4 KiB
C++
// This file is part of Eigen, a lightweight C++ template library
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// for linear algebra.
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//
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// Copyright (C) 2012 Désiré Nuentsa-Wakam <desire.nuentsa_wakam@inria.fr>
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//
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// This Source Code Form is subject to the terms of the Mozilla
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// Public License v. 2.0. If a copy of the MPL was not distributed
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// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
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/*
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* NOTE: This file is the modified version of [s,d,c,z]pruneL.c file in SuperLU
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* -- SuperLU routine (version 2.0) --
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* Univ. of California Berkeley, Xerox Palo Alto Research Center,
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* and Lawrence Berkeley National Lab.
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* November 15, 1997
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*
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* Copyright (c) 1994 by Xerox Corporation. All rights reserved.
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*
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* THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY
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* EXPRESSED OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
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*
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* Permission is hereby granted to use or copy this program for any
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* purpose, provided the above notices are retained on all copies.
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* Permission to modify the code and to distribute modified code is
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* granted, provided the above notices are retained, and a notice that
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* the code was modified is included with the above copyright notice.
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*/
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#ifndef SPARSELU_PRUNEL_H
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#define SPARSELU_PRUNEL_H
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namespace Eigen {
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namespace internal {
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/**
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* \brief Prunes the L-structure.
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*
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* It prunes the L-structure of supernodes whose L-structure contains the current pivot row "pivrow"
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*
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*
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* \param jcol The current column of L
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* \param[in] perm_r Row permutation
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* \param[out] pivrow The pivot row
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* \param nseg Number of segments
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* \param segrep
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* \param repfnz
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* \param[out] xprune
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* \param glu Global LU data
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*
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*/
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template <typename Scalar, typename Index>
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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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{
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// For each supernode-rep irep in U(*,j]
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Index jsupno = glu.supno(jcol);
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Index i,irep,irep1;
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bool movnum, do_prune = false;
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Index kmin = 0, kmax = 0, minloc, maxloc,krow;
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for (i = 0; i < nseg; i++)
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{
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irep = segrep(i);
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irep1 = irep + 1;
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do_prune = false;
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// Don't prune with a zero U-segment
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if (repfnz(irep) == emptyIdxLU) continue;
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// If a snode overlaps with the next panel, then the U-segment
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// is fragmented into two parts -- irep and irep1. We should let
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// pruning occur at the rep-column in irep1s snode.
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if (glu.supno(irep) == glu.supno(irep1) ) continue; // don't prune
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// If it has not been pruned & it has a nonz in row L(pivrow,i)
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if (glu.supno(irep) != jsupno )
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{
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if ( xprune (irep) >= glu.xlsub(irep1) )
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{
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kmin = glu.xlsub(irep);
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kmax = glu.xlsub(irep1) - 1;
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for (krow = kmin; krow <= kmax; krow++)
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{
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if (glu.lsub(krow) == pivrow)
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{
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do_prune = true;
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break;
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}
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}
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}
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if (do_prune)
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{
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// do a quicksort-type partition
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// movnum=true means that the num values have to be exchanged
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movnum = false;
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if (irep == glu.xsup(glu.supno(irep)) ) // Snode of size 1
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movnum = true;
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while (kmin <= kmax)
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{
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if (perm_r(glu.lsub(kmax)) == emptyIdxLU)
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kmax--;
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else if ( perm_r(glu.lsub(kmin)) != emptyIdxLU)
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kmin++;
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else
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{
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// kmin below pivrow (not yet pivoted), and kmax
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// above pivrow: interchange the two suscripts
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std::swap(glu.lsub(kmin), glu.lsub(kmax));
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// If the supernode has only one column, then we
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// only keep one set of subscripts. For any subscript
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// intercnahge performed, similar interchange must be
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// done on the numerical values.
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if (movnum)
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{
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minloc = glu.xlusup(irep) + ( kmin - glu.xlsub(irep) );
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maxloc = glu.xlusup(irep) + ( kmax - glu.xlsub(irep) );
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std::swap(glu.lusup(minloc), glu.lusup(maxloc));
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}
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kmin++;
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kmax--;
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}
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} // end while
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xprune(irep) = kmin; //Pruning
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} // end if do_prune
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} // end pruning
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} // End for each U-segment
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}
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} // end namespace internal
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} // end namespace Eigen
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#endif // SPARSELU_PRUNEL_H
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