1
       2
       3
       4
       5
       6
       7
       8
       9
      10
      11
      12
      13
      14
      15
      16
      17
      18
      19
      20
      21
      22
      23
      24
      25
      26
      27
      28
      29
      30
      31
      32
      33
      34
      35
      36
      37
      38
      39
      40
      41
      42
      43
      44
      45
      46
      47
      48
      49
      50
      51
      52
      53
      54
      55
      56
      57
      58
      59
      60
      61
      62
      63
      64
      65
      66
      67
      68
      69
      70
      71
      72
      73
      74
      75
      76
      77
      78
      79
      80
      81
      82
      83
      84
      85
      86
      87
      88
      89
      90
      91
      92
      93
      94
      95
      96
      97
      98
      99
     100
     101
     102
     103
     104
     105
     106
     107
     108
     109
     110
     111
     112
     113
     114
     115
     116
     117
     118
     119
     120
     121
     122
     123
     124
     125
     126
     127
     128
     129
     130
     131
     132
     133
     134
     135
     136
     137
     138
     139
     140
     141
     142
     143
     144
     145
     146
     147
     148
     149
     150
     151
     152
     153
     154
     155
     156
     157
     158
     159
     160
     161
     162
     163
     164
     165
     166
     167
     168
     169
     170
     171
     172
     173
     174
     175
     176
     177
     178
     179
     180
     181
     182
     183
     184
     185
     186
     187
     188
     189
     190
     191
     192
     193
     194
     195
     196
     197
     198
     199
     200
     201
     202
     203
     204
     205
     206
     207
     208
     209
     210
     211
     212
     213
     214
     215
     216
     217
     218
     219
     220
     221
     222
     223
     224
     225
     226
     227
     228
     229
     230
     231
     232
     233
     234
     235
     236
     237
     238
     239
     240
     241
     242
     243
     244
     245
     246
     247
     248
     249
     250
     251
     252
     253
     254
     255
     256
     257
     258
     259
     260
     261
     262
     263
     264
     265
     266
     267
     268
     269
     270
     271
     272
     273
     274
     275
     276
     277
     278
     279
     280
     281
     282
     283
     284
     285
     286
     287
     288
     289
     290
     291
     292
     293
     294
     295
     296
     297
     298
     299
     300
     301
     302
     303
     304
     305
     306
     307
     308
     309
     310
     311
     312
     313
     314
     315
     316
     317
     318
     319
     320
     321
     322
     323
     324
     325
     326
     327
     328
     329
     330
     331
     332
     333
     334
     335
     336
     337
     338
     339
     340
     341
     342
     343
     344
     345
     346
     347
     348
     349
     350
     351
     352
     353
     354
     355
     356
     357
     358
     359
     360
     361
     362
     363
     364
     365
     366
     367
     368
     369
     370
     371
     372
     373
     374
     375
     376
     377
     378
     379
     380
     381
     382
     383
     384
     385
     386
     387
     388
     389
     390
     391
     392
     393
     394
     395
     396
     397
     398
     399
     400
     401
     402
     403
     404
     405
     406
     407
     408
     409
     410
     411
     412
     413
     414
     415
     416
     417
     418
     419
     420
     421
     422
/*
 *   Copyright (c) 2011, Michael Lehn
 *
 *   All rights reserved.
 *
 *   Redistribution and use in source and binary forms, with or without
 *   modification, are permitted provided that the following conditions
 *   are met:
 *
 *   1) Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *   2) Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in
 *      the documentation and/or other materials provided with the
 *      distribution.
 *   3) Neither the name of the FLENS development group nor the names of
 *      its contributors may be used to endorse or promote products derived
 *      from this software without specific prior written permission.
 *
 *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/* Based on
 *
       SUBROUTINE DGEHRD( N, ILO, IHI, A, LDA, TAU, WORK, LWORK, INFO )
 *
 *  -- LAPACK routine (version 3.3.1)                                  --
 *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
 *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
 *  -- April 2009                                                      --
 */

#ifndef FLENS_LAPACK_GE_HRD_TCC
#define FLENS_LAPACK_GE_HRD_TCC 1

#include <flens/blas/blas.h>
#include <flens/lapack/lapack.h>

namespace flens { namespace lapack {

//== generic lapack implementation =============================================

namespace generic {

template <typename IndexType, typename MA>
IndexType
hrd_wsq_impl(IndexType iLo, IndexType iHi, const GeMatrix<MA> &A)
{
    using std::min;

    typedef typename GeMatrix<MA>::ElementType  T;

//
//  Perform and apply workspace query
//
    const IndexType nbMax = 64;
    const IndexType n   = A.numCols();

    return n*min(nbMax, IndexType(ilaenv<T>(1,"GEHRD""", n, iLo, iHi)));
}

template <typename IndexType, typename MA, typename VTAU, typename VWORK>
void
hrd_impl(IndexType           iLo,
         IndexType           iHi,
         GeMatrix<MA>        &A,
         DenseVector<VTAU>   &tau,
         DenseVector<VWORK>  &work)
{
    using std::max;
    using std::min;

    typedef typename GeMatrix<MA>::ElementType  T;
    typedef typename GeMatrix<MA>::View         GeView;
    typedef typename GeView::Engine             GeViewEngine;

    const Underscore<IndexType> _;

//
//  Paramters, e.g. maximum block size and buffer on stack for TrMatrix Tr.
//
    const T             One(1);
    const IndexType     nbMax = 64;
    const IndexType     ldt = nbMax1;
    T                   trBuffer[nbMax*ldt];
    GeView              _Tr = GeViewEngine(ldt, nbMax, trBuffer, ldt);
//
//  Perform and apply workspace query
//
    const IndexType n = A.numCols();
    IndexType       nb = min(nbMax,
                             IndexType(ilaenv<T>(1,"GEHRD""", n, iLo, iHi)));

    const IndexType lWorkOpt = n*nb;
    if (work.length()==0) {
        work.resize(lWorkOpt);
        work(1) = lWorkOpt;
    }
//
//  Set elements 1:iLo-1 and iHi:n-1 of tau to zero
//
    tau(_(1,iLo-1)) = 0;
    tau(_(max(IndexType(1),iHi),n-1)) = 0;
//
//  Quick return if possible
//
    const IndexType nh = iHi - iLo1;
    if (nh<=1) {
        work(1) = 1;
        return;
    }
//
//  Determine the block size
//
    IndexType nbMin = 2;
    IndexType iws = 1;
    IndexType nx = 0;

    if (nb>1 && nb<nh) {
//
//      Determine when to cross over from blocked to unblocked code
//      (last block is always handled by unblocked code)
//
        nx = max(nb, IndexType(ilaenv<T>(3"GEHRD""", n, iLo, iHi)));
        if (nx<nh) {
//
//          Determine if workspace is large enough for blocked code
//
            iws = n*nb;
            if (work.length()<iws) {
//
//              Not enough workspace to use optimal NB:  determine the
//              minimum value of NB, and reduce NB or force use of
//              unblocked code
//
                nbMin = max(2, ilaenv<T>(2"GEHRD""", n, iLo, iHi));
                if (work.length()>=n*nbMin) {
                    nb = work.length() / n;
                } else {
                    nb1;
                }
            }
        }
    }
    IndexType ldWork = n;
    IndexType i = iLo;
    if (nb<nbMin || nb>=nh) {
//
//      Use unblocked code below
//
    } else {
//
//      Use blocked code
//
        for (i=iLo; i<=iHi-1-nx; i+=nb) {
            const IndexType ib = min(nb, iHi-i);
            auto  Tr = _Tr(_(1,ib),_(1,ib)).upper();
            GeView  Y(iHi, ib, work, ldWork);
//
//          Reduce columns i:i+ib-1 to Hessenberg form, returning the
//          matrices V and T of the block reflector H = I - V*T*V**T
//          which performs the reduction, and also the matrix Y = A*V*T
//
            lahr2(i, ib, A(_(1,iHi),_(i,iHi)), tau(_(i,i+ib-1)), Tr, Y);
//
//          Partition V and the parts of matrix A that get modified
//
            auto V1 = A(_(i+1, i+ib-1),_(i,i+ib-2));
            auto V2 = A(_(i+ib,   iHi),_(i,i+ib-1));
//
//          Apply the block reflector H to A(1:ihi,i+ib:ihi) from the
//          right, computing  A := A - Y * V**T. V(i+ib,ib-1) must be set
//          to 1
//
            T ei = A(i+ib,i+ib-1);
            A(i+ib,i+ib-1) = One;
            blas::mm(NoTrans, Trans, -One, Y, V2, One, A(_(1,iHi),_(i+ib,iHi)));
            A(i+ib,i+ib-1) = ei;
//
//          Apply the block reflector H to A(1:i,i+1:i+ib-1) from the
//          right
//
            blas::mm(Right, Trans, One, V1.lowerUnit(), Y(_(1,i),_(1,ib-1)));
            A(_(1,i),_(i+1,i+ib-1)) -= Y(_(1,i),_(1,ib-1));
//
//          Apply the block reflector H to A(i+1:ihi,i+ib:n) from the
//          left
//
            GeView  Work(n-i-ib+1, ib, work, ldWork);
            larfb(Left, Trans, Forward, ColumnWise,
                  A(_(i+1,iHi),_(i,i+ib-1)),
                  Tr,
                  A(_(i+1,iHi),_(i+ib,n)),
                  Work);
        }
    }
//
//  Use unblocked code to reduce the rest of the matrix
//
    hd2(i, iHi, A, tau, work);
    work(1) = iws;
}

// namespace generic

//== interface for native lapack ===============================================

#ifdef USE_CXXLAPACK

namespace external {

template <typename IndexType, typename MA>
IndexType
hrd_wsq_impl(IndexType            iLo,
             IndexType            iHi,
             const GeMatrix<MA>   &A)
{
    typedef typename GeMatrix<MA>::ElementType  T;

    T                   WORK, DUMMY;
    const IndexType     LWORK  = -1;

    cxxlapack::gehrd<IndexType>(A.numRows(),
                                iLo,
                                iHi,
                                &DUMMY,
                                A.leadingDimension(),
                                &DUMMY,
                                &WORK,
                                LWORK);
    return WORK;
}

template <typename IndexType, typename MA, typename VTAU, typename VWORK>
void
hrd_impl(IndexType            iLo,
         IndexType            iHi,
         GeMatrix<MA>         &A,
         DenseVector<VTAU>    &tau,
         DenseVector<VWORK>   &work)
{
    cxxlapack::gehrd<IndexType>(A.numRows(),
                                iLo,
                                iHi,
                                A.data(),
                                A.leadingDimension(),
                                tau.data(),
                                work.data(),
                                work.length());
}

// namespace external

#endif // USE_CXXLAPACK

//== public interface ==========================================================

template <typename IndexType, typename MA>
IndexType
hrd_wsq(IndexType           iLo,
        IndexType           iHi,
        const GeMatrix<MA>  &A)
{
    LAPACK_DEBUG_OUT("hrd_wsq");

//
//  Test the input parameters
//
#   ifndef NDEBUG
    ASSERT(A.firstRow()==1);
    ASSERT(A.firstCol()==1);
    ASSERT(A.numRows()==A.numCols());
#   endif

//
//  Call implementation
//
    IndexType info = LAPACK_SELECT::hrd_wsq_impl(iLo, iHi, A);

#   ifdef CHECK_CXXLAPACK
//
//  Compare results
//
    IndexType _info = external::hrd_wsq_impl(iLo, iHi, A);

    if (! isIdentical(info, _info, " info""_info")) {
        ASSERT(0);
    }
#   endif

    return info;
}

template <typename IndexType, typename MA, typename VTAU, typename VWORK>
void
hrd(IndexType           iLo,
    IndexType           iHi,
    GeMatrix<MA>        &A,
    DenseVector<VTAU>   &tau,
    DenseVector<VWORK>  &work)
{
    LAPACK_DEBUG_OUT("hrd");

    using std::max;
//
//  Test the input parameters
//
#   ifndef NDEBUG
    ASSERT(A.firstRow()==1);
    ASSERT(A.firstCol()==1);
    ASSERT(A.numRows()==A.numCols());
    ASSERT(tau.firstIndex()==1);

    const IndexType n = A.numCols();

    if (n==0) {
        ASSERT(iLo==1);
        ASSERT(iHi==0);
    } else {
        ASSERT(1<=iLo);
        ASSERT(iLo<=iHi);
        ASSERT(iHi<=n);
    }

    ASSERT(tau.length()==(n-1));
    const bool lQuery = (work.length()==0);
    ASSERT(lQuery || (work.length()>=max(IndexType(1),n)));
#   endif

//
//  Make copies of output arguments
//
#   ifdef CHECK_CXXLAPACK
    typename GeMatrix<MA>::NoView       _A = A;
    typename DenseVector<VTAU>::NoView  _tau = tau;
    typename DenseVector<VWORK>::NoView _work = work;
#   endif

//
//  Call implementation
//
    LAPACK_SELECT::hrd_impl(iLo, iHi, A, tau, work);

#   ifdef CHECK_CXXLAPACK
//
//  Compare results
//
    if (_work.length()==0) {
        _work.resize(work.length());
    }
    external::hrd_impl(iLo, iHi, _A, _tau, _work);

    bool failed = false;
    if (! isIdentical(A, _A, " A""_A")) {
        std::cerr << "CXXLAPACK:  A = " << A << std::endl;
        std::cerr << "F77LAPACK: _A = " << _A << std::endl;
        failed = true;
    }

    if (! isIdentical(tau, _tau, " tau""_tau")) {
        std::cerr << "CXXLAPACK:  tau = " << tau << std::endl;
        std::cerr << "F77LAPACK: _tau = " << _tau << std::endl;
        failed = true;
    }

    if (! isIdentical(work, _work, " work""_work")) {
        std::cerr << "CXXLAPACK:  work = " << work << std::endl;
        std::cerr << "F77LAPACK: _work = " << _work << std::endl;
        failed = true;
    }

    if (failed) {
        std::cerr << "error in: hrd.tcc" << std::endl;
        ASSERT(0);
    } else {
//        std::cerr << "passed: hrd.tcc" << std::endl;
    }

#   endif
}

//-- forwarding ----------------------------------------------------------------
template <typename IndexType, typename MA>
IndexType
hrd_wsq(IndexType   iLo,
        IndexType   iHi,
        const MA    &&A)
{
    CHECKPOINT_ENTER;
    const IndexType info = hrd_wsq(iLo, iHi, A);
    CHECKPOINT_LEAVE;

    return info;
}

template <typename IndexType, typename MA,
          typename VTAU, typename VWORK>
void
hrd(IndexType       iLo,
    IndexType       iHi,
    MA              &&A,
    VTAU            &&tau,
    VWORK           &&work)
{
    CHECKPOINT_ENTER;
    hrd(iLo, iHi, A, tau, work);
    CHECKPOINT_LEAVE;
}

} } // namespace lapack, flens

#endif // FLENS_LAPACK_GE_HRD_TCC