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Symbolic and numeric update on a whole panel
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Desire NUENTSA
178
Eigen/src/SparseLU/SparseLU_panel_bmod.h
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178
Eigen/src/SparseLU/SparseLU_panel_bmod.h
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// 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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// Eigen is free software; you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public
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// License as published by the Free Software Foundation; either
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// version 3 of the License, or (at your option) any later version.
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//
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// Alternatively, you can redistribute it and/or
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// modify it under the terms of the GNU General Public License as
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// published by the Free Software Foundation; either version 2 of
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// the License, or (at your option) any later version.
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//
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// Eigen is distributed in the hope that it will be useful, but WITHOUT ANY
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// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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// FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License or the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public
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// License and a copy of the GNU General Public License along with
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// Eigen. If not, see <http://www.gnu.org/licenses/>.
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/*
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* NOTE: This file is the modified version of xpanel_dfs.c file in SuperLU
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* -- SuperLU routine (version 3.0) --
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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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* October 15, 2003
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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_PANEL_BMOD_H
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#define SPARSELU_PANEL_BMOD_H
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/**
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* \brief Performs numeric block updates (sup-panel) in topological order.
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*
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* Before entering this routine, the original nonzeros in the panel
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* were already copied i nto the spa[m,w] ... FIXME to be checked
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*
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* \param m number of rows in the matrix
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* \param w Panel size
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* \param jcol Starting column of the panel
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* \param nseg Number of segments in the U part
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* \param dense Store the full representation of the panel
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* \param tempv working array
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* \param segrep in ...
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* \param repfnz in ...
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* \param Glu Global LU data.
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*
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*
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*/
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template <typename VectorType>
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void SparseLU::LU_panel_bmod(const int m, const int w, const int jcol, const int nseg, VectorType& dense, VectorType& tempv, VectorXi& segrep, VectorXi& repfnz, LU_GlobalLu_t& Glu)
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{
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VectorXi& xsup = Glu.xsup;
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VectorXi& supno = Glu.supno;
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VectorXi& lsub = Glu.lsub;
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VectorXi& xlsub = Glu.xlsub;
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VectorXi& xlusup = Glu.xlusup;
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VectorType& lusup = Glu.lusup;
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int i,ksub,jj,nextl_col,irow;
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int fsupc, nsupc, nsupr, nrow;
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int krep, krep_ind;
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int nrow;
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int lptr; // points to the row subscripts of a supernode
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int luptr; // ...
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int segsze,no_zeros,irow ;
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// For each nonz supernode segment of U[*,j] in topological order
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int k = nseg - 1;
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for (ksub = 0; ksub < nseg; ksub++)
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{ // For each updating supernode
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/* krep = representative of current k-th supernode
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* fsupc = first supernodal column
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* nsupc = number of columns in a supernode
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* nsupr = number of rows in a supernode
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*/
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krep = segrep(k); k--;
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fsupc = xsup(supno(krep));
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nsupc = krep - fsupc + 1;
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nsupr = xlsub(fsupc+1) - xlsub(fsupc);
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nrow = nsupr - nsupc;
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lptr = xlsub(fsupc);
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krep_ind = lptr + nsupc - 1;
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repfnz_col = repfnz;
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dense_col = dense;
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// NOTE : Unlike the original implementation in SuperLU, the present implementation
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// does not include a 2-D block update.
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// Sequence through each column in the panel
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for (jj = jcol; jj < jcol + w; jj++)
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{
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nextl_col = (jj-jcol) * m;
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VectorBlock<VectorXi> repfnz_col(repfnz.segment(nextl_col, m)); // First nonzero column index for each row
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VectorBLock<VectorXi> dense_col(dense.segment(nextl_col, m)); // Scatter/gather entire matrix column from/to here
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kfnz = repfnz_col(krep);
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if ( kfnz == -1 )
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continue; // skip any zero segment
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segsize = krep - kfnz + 1;
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luptr = xlusup(fsupc);
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// NOTE : Unlike the original implementation in SuperLU,
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// there is no update feature for col-col, 2col-col ...
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// Perform a trianglar solve and block update,
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// then scatter the result of sup-col update to dense[]
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no_zeros = kfnz - fsupc;
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// Copy U[*,j] segment from dense[*] to tempv[*] :
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// The result of triangular solve is in tempv[*];
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// The result of matric-vector update is in dense_col[*]
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isub = lptr + no_zeros;
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for (i = 0; i < segsize; ++i)
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{
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irow = lsub(isub);
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tempv(i) = dense_col(irow); // Gather to a compact vector
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++isub;
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}
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// Start effective triangle
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luptr += nsupr * no_zeros + no_zeros;
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// triangular solve with Eigen
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Map<Matrix<Scalar,Dynamic, Dynamic>, 0, OuterStride<> > A( &(lusup.data()[luptr]), segsize, segsize, OuterStride<>(nsupr) );
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Map<Matrix<Scalar,Dynamic,1> > u( tempv.data(), segsize);
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u = A.triangularView<Lower>().solve(u);
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luptr += segsize;
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// Dense Matrix vector product y <-- A*x;
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new (&A) Map<Matrix<Scalar,Dynamic, Dynamic>, 0, OuterStride<> > ( &(lusup.data()[luptr]), segsize, segsize, OuterStride<>(nsupr) );
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Map<VectorType> l( &(tempv.data()[segsize]), segsize);
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l= A * u;
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// Scatter tempv(*) into SPA dense(*) such that tempv(*)
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// can be used for the triangular solve of the next
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// column of the panel. The y will be copied into ucol(*)
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// after the whole panel has been finished.
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isub = lptr + no_zeros;
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for (i = 0; i < segsize; i++)
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{
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irow = lsub(isub);
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dense_col(irow) = tempv(i);
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tempv(i) = zero;
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isub++;
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}
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// Scatter the update from &tempv[segsize] into SPA dense(*)
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// Start dense rectangular L
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for (i = 0; i < nrow; i++)
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{
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irow = lsub(isub);
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dense_col(irow) -= tempv(segsize + i);
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tempv(segsize + i) = 0;
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++isub;
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}
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} // End for each column in the panel
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} // End for each updating supernode
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}
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#endif
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