// 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/.
/* * NOTE: This file is the modified version of [s,d,c,z]column_dfs.c file in SuperLU * -- SuperLU routine (version 2.0) -- * Univ. of California Berkeley, Xerox Palo Alto Research Center, * and Lawrence Berkeley National Lab. * November 15, 1997 * * 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_COLUMN_DFS_H #define SPARSELU_COLUMN_DFS_H
template <typename Scalar, typename StorageIndex> class SparseLUImpl; namespace Eigen {
/** * \brief Performs a symbolic factorization on column jcol and decide the supernode boundary * * A supernode representative is the last column of a supernode. * The nonzeros in U[*,j] are segments that end at supernodes representatives. * The routine returns a list of the supernodal representatives * in topological order of the dfs that generates them. * The location of the first nonzero in each supernodal segment * (supernodal entry location) is also returned. * * \param m number of rows in the matrix * \param jcol Current column * \param perm_r Row permutation * \param maxsuper Maximum number of column allowed in a supernode * \param [in,out] nseg Number of segments in current U[*,j] - new segments appended * \param lsub_col defines the rhs vector to start the dfs * \param [in,out] segrep Segment representatives - new segments appended * \param repfnz First nonzero location in each row * \param xprune * \param marker marker[i] == jj, if i was visited during dfs of current column jj; * \param parent * \param xplore working array * \param glu global LU data * \return 0 success * > 0 number of bytes allocated when run out of space *
*/ template <typename Scalar, typename StorageIndex>
Index SparseLUImpl<Scalar,StorageIndex>::column_dfs(const Index m, const Index jcol, IndexVector& perm_r, Index maxsuper, Index& nseg,
BlockIndexVector lsub_col, IndexVector& segrep, BlockIndexVector repfnz, IndexVector& xprune,
IndexVector& marker, IndexVector& parent, IndexVector& xplore, GlobalLU_t& glu)
{
Index jsuper = glu.supno(jcol);
Index nextl = glu.xlsub(jcol);
VectorBlock<IndexVector> marker2(marker, 2*m, m);
// For each nonzero in A(*,jcol) do dfs for (Index k = 0; ((k < m) ? lsub_col[k] != emptyIdxLU : false) ; k++)
{
Index krow = lsub_col(k);
lsub_col(k) = emptyIdxLU;
Index kmark = marker2(krow);
// krow was visited before, go to the next nonz; if (kmark == jcol) continue;
dfs_kernel(StorageIndex(jcol), perm_r, nseg, glu.lsub, segrep, repfnz, xprune, marker2, parent,
xplore, glu, nextl, krow, traits);
} // for each nonzero ...
Index fsupc;
StorageIndex nsuper = glu.supno(jcol);
StorageIndex jcolp1 = StorageIndex(jcol) + 1;
Index jcolm1 = jcol - 1;
// check to see if j belongs in the same supernode as j-1 if ( jcol == 0 )
{ // Do nothing for column 0
nsuper = glu.supno(0) = 0 ;
} else
{
fsupc = glu.xsup(nsuper);
StorageIndex jptr = glu.xlsub(jcol); // Not yet compressed
StorageIndex jm1ptr = glu.xlsub(jcolm1);
// Use supernodes of type T2 : see SuperLU paper if ( (nextl-jptr != jptr-jm1ptr-1) ) jsuper = emptyIdxLU;
// Make sure the number of columns in a supernode doesn't // exceed threshold if ( (jcol - fsupc) >= maxsuper) jsuper = emptyIdxLU;
/* If jcol starts a new supernode, reclaim storage space in * glu.lsub from previous supernode. Note we only store * the subscript set of the first and last columns of * a supernode. (first for num values, last for pruning)
*/ if (jsuper == emptyIdxLU)
{ // starts a new supernode if ( (fsupc < jcolm1-1) )
{ // >= 3 columns in nsuper
StorageIndex ito = glu.xlsub(fsupc+1);
glu.xlsub(jcolm1) = ito;
StorageIndex istop = ito + jptr - jm1ptr;
xprune(jcolm1) = istop; // initialize xprune(jcol-1)
glu.xlsub(jcol) = istop;
for (StorageIndex ifrom = jm1ptr; ifrom < nextl; ++ifrom, ++ito)
glu.lsub(ito) = glu.lsub(ifrom);
nextl = ito; // = istop + length(jcol)
}
nsuper++;
glu.supno(jcol) = nsuper;
} // if a new supernode
} // end else: jcol > 0
// Tidy up the pointers before exit
glu.xsup(nsuper+1) = jcolp1;
glu.supno(jcolp1) = nsuper;
xprune(jcol) = StorageIndex(nextl); // Initialize upper bound for pruning
glu.xlsub(jcolp1) = StorageIndex(nextl);
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