1 /*
  2  *   Copyright (c) 2011, Michael Lehn
  3  *
  4  *   All rights reserved.
  5  *
  6  *   Redistribution and use in source and binary forms, with or without
  7  *   modification, are permitted provided that the following conditions
  8  *   are met:
  9  *
 10  *   1) Redistributions of source code must retain the above copyright
 11  *      notice, this list of conditions and the following disclaimer.
 12  *   2) Redistributions in binary form must reproduce the above copyright
 13  *      notice, this list of conditions and the following disclaimer in
 14  *      the documentation and/or other materials provided with the
 15  *      distribution.
 16  *   3) Neither the name of the FLENS development group nor the names of
 17  *      its contributors may be used to endorse or promote products derived
 18  *      from this software without specific prior written permission.
 19  *
 20  *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 21  *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 22  *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 23  *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 24  *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 25  *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 26  *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 27  *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 28  *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 29  *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 30  *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 31  */
 32 
 33 /* Based on
 34  *
 35  *     INTEGER FUNCTION ILA?LC( M, N, A, LDA )
 36  *
 37  *  -- LAPACK auxiliary routine (version 3.2.2)                        --
 38  *
 39  *  -- June 2010                                                       --
 40  *
 41  *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
 42  *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
 43  */
 44 
 45 #ifndef FLENS_LAPACK_AUX_ILALC_TCC
 46 #define FLENS_LAPACK_AUX_ILALC_TCC 1
 47 
 48 #include <flens/blas/blas.h>
 49 #include <flens/lapack/lapack.h>
 50 
 51 namespace flens { namespace lapack {
 52 
 53 //== generic lapack implementation =============================================
 54 
 55 template <typename MA>
 56 typename GeMatrix<MA>::IndexType
 57 ilalc_generic(const GeMatrix<MA> &A)
 58 {
 59     typedef typename GeMatrix<MA>::IndexType    IndexType;
 60     typedef typename GeMatrix<MA>::ElementType  T;
 61 
 62     const IndexType m = A.numRows();
 63     const IndexType n = A.numCols();
 64 
 65 //
 66 //  Quick test for the common case where one corner is non-zero.
 67 //
 68     if (n==0) {
 69         return n;
 70     } else if ((A(1,n)!=T(0)) || A(m,n)!=T(0)) {
 71         return n;
 72     } else {
 73 //
 74 //      Now scan each column from the end, returning with the first non-zero.
 75 //
 76         for (IndexType j=n; j>=1; --j) {
 77             for (IndexType i=1; i<=m; ++i) {
 78                 if (A(i,j)!=T(0)) {
 79                     return j;
 80                 }
 81             }
 82         }
 83     }
 84     return 0;
 85 }
 86 
 87 //== interface for native lapack ===============================================
 88 
 89 
 90 //== public interface ==========================================================
 91 
 92 template <typename MA>
 93 typename GeMatrix<MA>::IndexType
 94 ilalc(const GeMatrix<MA> &A)
 95 {
 96     LAPACK_DEBUG_OUT("ilalc");
 97 
 98     ASSERT(A.firstRow()==1);
 99     ASSERT(A.firstCol()==1);
100 
101     return ilalc_generic(A);
102 }
103 
104 } } // namespace lapack, flens
105 
106 #endif // FLENS_LAPACK_AUX_ILALC_TCC