Eigen/src/SparseLU/SparseLU_copy_to_ucol.h

// 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]copy_to_ucol.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_COPY_TO_UCOL_H
#define SPARSELU_COPY_TO_UCOL_H

// IWYU pragma: private
#include "./InternalHeaderCheck.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 segrep segment representative ...
 * \param repfnz First nonzero column in each row  ...
 * \param perm_r Row permutation
 * \param dense Store the full representation of the column
 * \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>::copy_to_ucol(const Index jcol, const Index nseg, IndexVector& segrep,
                                                       BlockIndexVector repfnz, IndexVector& perm_r,
                                                       BlockScalarVector dense, GlobalLU_t& glu) {
  Index ksub, krep, ksupno;

  Index jsupno = glu.supno(jcol);

  // For each nonzero supernode segment of U[*,j] in topological order
  Index k = nseg - 1, i;
  StorageIndex nextu = glu.xusub(jcol);
  Index kfnz, isub, segsize;
  Index new_next, irow;
  Index fsupc, mem;
  for (ksub = 0; ksub < nseg; ksub++) {
    krep = segrep(k);
    k--;
    ksupno = glu.supno(krep);
    if (jsupno != ksupno)  // should go into ucol();
    {
      kfnz = repfnz(krep);
      if (kfnz != emptyIdxLU) {  // Nonzero U-segment
        fsupc = glu.xsup(ksupno);
        isub = glu.xlsub(fsupc) + kfnz - fsupc;
        segsize = krep - kfnz + 1;
        new_next = nextu + segsize;
        while (new_next > glu.nzumax) {
          mem = memXpand<ScalarVector>(glu.ucol, glu.nzumax, nextu, UCOL, glu.num_expansions);
          if (mem) return mem;
          mem = memXpand<IndexVector>(glu.usub, glu.nzumax, nextu, USUB, glu.num_expansions);
          if (mem) return mem;
        }

        for (i = 0; i < segsize; i++) {
          irow = glu.lsub(isub);
          glu.usub(nextu) = perm_r(irow);  // Unlike the L part, the U part is stored in its final order
          glu.ucol(nextu) = dense(irow);
          dense(irow) = Scalar(0.0);
          nextu++;
          isub++;
        }

      }  // end nonzero U-segment

    }  // end if jsupno

  }                             // end for each segment
  glu.xusub(jcol + 1) = nextu;  // close U(*,jcol)
  return 0;
}

}  // namespace internal
}  // end namespace Eigen

#endif  // SPARSELU_COPY_TO_UCOL_H