// 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>
// Copyright (C) 2012 Gael Guennebaud <gael.guennebaud@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 xcolumn_bmod.c file in SuperLU
* -- SuperLU routine (version 3.0) --
* Univ. of California Berkeley, Xerox Palo Alto Research Center,
* and Lawrence Berkeley National Lab.
* October 15, 2003
*
* 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_BMOD_H
#define SPARSELU_COLUMN_BMOD_H
namespace Eigen {
namespace internal {
/**
* \brief Performs numeric block updates (sup-col) in topological order
*
* \param jcol current column to update
* \param nseg Number of segments in the U part
* \param dense Store the full representation of the column
* \param tempv working array
* \param segrep segment representative ...
* \param repfnz ??? First nonzero column in each row ??? ...
* \param fpanelc First column in the current panel
* \param glu Global LU data.
* \return 0 - successful return
* > 0 - number of bytes allocated when run out of space
*
*/
template <typename Scalar, typename StorageIndex>
Index SparseLUImpl<Scalar,StorageIndex>::column_bmod(const Index jcol, const Index nseg, BlockScalarVector dense, ScalarVector& tempv,
BlockIndexVector segrep, BlockIndexVector repfnz, Index fpanelc, GlobalLU_t& glu)
{
Index jsupno, k, ksub, krep, ksupno;
Index lptr, nrow, isub, irow, nextlu, new_next, ufirst;
Index fsupc, nsupc, nsupr, luptr, kfnz, no_zeros;
/* krep = representative of current k-th supernode
* fsupc = first supernodal column
* nsupc = number of columns in a supernode
* nsupr = number of rows in a supernode
* luptr = location of supernodal LU-block in storage
* kfnz = first nonz in the k-th supernodal segment
* no_zeros = no lf leading zeros in a supernodal U-segment
*/
jsupno = glu.supno(jcol);
// For each nonzero supernode segment of U[*,j] in topological order
k = nseg - 1;
Index d_fsupc; // distance between the first column of the current panel and the
// first column of the current snode
Index fst_col; // First column within small LU update
Index segsize;
for (ksub = 0; ksub < nseg; ksub++)
{
krep = segrep(k); k--;
ksupno = glu.supno(krep);
if (jsupno != ksupno )
{
// outside the rectangular supernode
fsupc = glu.xsup(ksupno);
fst_col = (std::max)(fsupc, fpanelc);
// Distance from the current supernode to the current panel;
// d_fsupc = 0 if fsupc > fpanelc
d_fsupc = fst_col - fsupc;
luptr = glu.xlusup(fst_col) + d_fsupc;
lptr = glu.xlsub(fsupc) + d_fsupc;
kfnz = repfnz(krep);
kfnz = (std::max)(kfnz, fpanelc);
segsize = krep - kfnz + 1;
nsupc = krep - fst_col + 1;
nsupr = glu.xlsub(fsupc+1) - glu.xlsub(fsupc);
nrow = nsupr - d_fsupc - nsupc;
Index lda = glu.xlusup(fst_col+1) - glu.xlusup(fst_col);
// Perform a triangular solver and block update,
// then scatter the result of sup-col update to dense
no_zeros = kfnz - fst_col;
if(segsize==1)
LU_kernel_bmod<1>::run(segsize, dense, tempv, glu.lusup, luptr, lda, nrow, glu.lsub, lptr, no_zeros);
else
LU_kernel_bmod<Dynamic>::run(segsize, dense, tempv, glu.lusup, luptr, lda, nrow, glu.lsub, lptr, no_zeros);
} // end if jsupno
} // end for each segment
// Process the supernodal portion of L\U[*,j]
nextlu = glu.xlusup(jcol);
fsupc = glu.xsup(jsupno);
// copy the SPA dense into L\U[*,j]
Index mem;
new_next = nextlu + glu.xlsub(fsupc + 1) - glu.xlsub(fsupc);
Index offset = internal::first_multiple<Index>(new_next, internal::packet_traits<Scalar>::size) - new_next;
if(offset)
new_next += offset;
while (new_next > glu.nzlumax )
{
mem = memXpand<ScalarVector>(glu.lusup, glu.nzlumax, nextlu, LUSUP, glu.num_expansions);
if (mem) return mem;
}
for (isub = glu.xlsub(fsupc); isub < glu.xlsub(fsupc+1); isub++)
{
irow = glu.lsub(isub);
glu.lusup(nextlu) = dense(irow);
dense(irow) = Scalar(0.0);
++nextlu;
}
if(offset)
{
glu.lusup.segment(nextlu,offset).setZero();
nextlu += offset;
}
glu.xlusup(jcol + 1) = StorageIndex(nextlu); // close L\U(*,jcol);
/* For more updates within the panel (also within the current supernode),
* should start from the first column of the panel, or the first column
* of the supernode, whichever is bigger. There are two cases:
* 1) fsupc < fpanelc, then fst_col <-- fpanelc
* 2) fsupc >= fpanelc, then fst_col <-- fsupc
*/
fst_col = (std::max)(fsupc, fpanelc);
if (fst_col < jcol)
{
// Distance between the current supernode and the current panel
// d_fsupc = 0 if fsupc >= fpanelc
d_fsupc = fst_col - fsupc;
lptr = glu.xlsub(fsupc) + d_fsupc;
luptr = glu.xlusup(fst_col) + d_fsupc;
nsupr = glu.xlsub(fsupc+1) - glu.xlsub(fsupc); // leading dimension
nsupc = jcol - fst_col; // excluding jcol
nrow = nsupr - d_fsupc - nsupc;
// points to the beginning of jcol in snode L\U(jsupno)
ufirst = glu.xlusup(jcol) + d_fsupc;
Index lda = glu.xlusup(jcol+1) - glu.xlusup(jcol);
MappedMatrixBlock A( &(glu.lusup.data()[luptr]), nsupc, nsupc, OuterStride<>(lda) );
VectorBlock<ScalarVector> u(glu.lusup, ufirst, nsupc);
u = A.template triangularView<UnitLower>().solve(u);
new (&A) MappedMatrixBlock ( &(glu.lusup.data()[luptr+nsupc]), nrow, nsupc, OuterStride<>(lda) );
VectorBlock<ScalarVector> l(glu.lusup, ufirst+nsupc, nrow);
l.noalias() -= A * u;
} // End if fst_col
return 0;
}
} // end namespace internal
} // end namespace Eigen
#endif // SPARSELU_COLUMN_BMOD_H