LAPACK  3.4.1
LAPACK: Linear Algebra PACKage
clauum.f
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00001 *> \brief \b CLAUUM
00002 *
00003 *  =========== DOCUMENTATION ===========
00004 *
00005 * Online html documentation available at 
00006 *            http://www.netlib.org/lapack/explore-html/ 
00007 *
00008 *> \htmlonly
00009 *> Download CLAUUM + dependencies 
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00011 *> [TGZ]</a> 
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00013 *> [ZIP]</a> 
00014 *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/clauum.f"> 
00015 *> [TXT]</a>
00016 *> \endhtmlonly 
00017 *
00018 *  Definition:
00019 *  ===========
00020 *
00021 *       SUBROUTINE CLAUUM( UPLO, N, A, LDA, INFO )
00022 * 
00023 *       .. Scalar Arguments ..
00024 *       CHARACTER          UPLO
00025 *       INTEGER            INFO, LDA, N
00026 *       ..
00027 *       .. Array Arguments ..
00028 *       COMPLEX            A( LDA, * )
00029 *       ..
00030 *  
00031 *
00032 *> \par Purpose:
00033 *  =============
00034 *>
00035 *> \verbatim
00036 *>
00037 *> CLAUUM computes the product U * U**H or L**H * L, where the triangular
00038 *> factor U or L is stored in the upper or lower triangular part of
00039 *> the array A.
00040 *>
00041 *> If UPLO = 'U' or 'u' then the upper triangle of the result is stored,
00042 *> overwriting the factor U in A.
00043 *> If UPLO = 'L' or 'l' then the lower triangle of the result is stored,
00044 *> overwriting the factor L in A.
00045 *>
00046 *> This is the blocked form of the algorithm, calling Level 3 BLAS.
00047 *> \endverbatim
00048 *
00049 *  Arguments:
00050 *  ==========
00051 *
00052 *> \param[in] UPLO
00053 *> \verbatim
00054 *>          UPLO is CHARACTER*1
00055 *>          Specifies whether the triangular factor stored in the array A
00056 *>          is upper or lower triangular:
00057 *>          = 'U':  Upper triangular
00058 *>          = 'L':  Lower triangular
00059 *> \endverbatim
00060 *>
00061 *> \param[in] N
00062 *> \verbatim
00063 *>          N is INTEGER
00064 *>          The order of the triangular factor U or L.  N >= 0.
00065 *> \endverbatim
00066 *>
00067 *> \param[in,out] A
00068 *> \verbatim
00069 *>          A is COMPLEX array, dimension (LDA,N)
00070 *>          On entry, the triangular factor U or L.
00071 *>          On exit, if UPLO = 'U', the upper triangle of A is
00072 *>          overwritten with the upper triangle of the product U * U**H;
00073 *>          if UPLO = 'L', the lower triangle of A is overwritten with
00074 *>          the lower triangle of the product L**H * L.
00075 *> \endverbatim
00076 *>
00077 *> \param[in] LDA
00078 *> \verbatim
00079 *>          LDA is INTEGER
00080 *>          The leading dimension of the array A.  LDA >= max(1,N).
00081 *> \endverbatim
00082 *>
00083 *> \param[out] INFO
00084 *> \verbatim
00085 *>          INFO is INTEGER
00086 *>          = 0: successful exit
00087 *>          < 0: if INFO = -k, the k-th argument had an illegal value
00088 *> \endverbatim
00089 *
00090 *  Authors:
00091 *  ========
00092 *
00093 *> \author Univ. of Tennessee 
00094 *> \author Univ. of California Berkeley 
00095 *> \author Univ. of Colorado Denver 
00096 *> \author NAG Ltd. 
00097 *
00098 *> \date November 2011
00099 *
00100 *> \ingroup complexOTHERauxiliary
00101 *
00102 *  =====================================================================
00103       SUBROUTINE CLAUUM( UPLO, N, A, LDA, INFO )
00104 *
00105 *  -- LAPACK auxiliary routine (version 3.4.0) --
00106 *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
00107 *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
00108 *     November 2011
00109 *
00110 *     .. Scalar Arguments ..
00111       CHARACTER          UPLO
00112       INTEGER            INFO, LDA, N
00113 *     ..
00114 *     .. Array Arguments ..
00115       COMPLEX            A( LDA, * )
00116 *     ..
00117 *
00118 *  =====================================================================
00119 *
00120 *     .. Parameters ..
00121       REAL               ONE
00122       PARAMETER          ( ONE = 1.0E+0 )
00123       COMPLEX            CONE
00124       PARAMETER          ( CONE = ( 1.0E+0, 0.0E+0 ) )
00125 *     ..
00126 *     .. Local Scalars ..
00127       LOGICAL            UPPER
00128       INTEGER            I, IB, NB
00129 *     ..
00130 *     .. External Functions ..
00131       LOGICAL            LSAME
00132       INTEGER            ILAENV
00133       EXTERNAL           LSAME, ILAENV
00134 *     ..
00135 *     .. External Subroutines ..
00136       EXTERNAL           CGEMM, CHERK, CLAUU2, CTRMM, XERBLA
00137 *     ..
00138 *     .. Intrinsic Functions ..
00139       INTRINSIC          MAX, MIN
00140 *     ..
00141 *     .. Executable Statements ..
00142 *
00143 *     Test the input parameters.
00144 *
00145       INFO = 0
00146       UPPER = LSAME( UPLO, 'U' )
00147       IF( .NOT.UPPER .AND. .NOT.LSAME( UPLO, 'L' ) ) THEN
00148          INFO = -1
00149       ELSE IF( N.LT.0 ) THEN
00150          INFO = -2
00151       ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
00152          INFO = -4
00153       END IF
00154       IF( INFO.NE.0 ) THEN
00155          CALL XERBLA( 'CLAUUM', -INFO )
00156          RETURN
00157       END IF
00158 *
00159 *     Quick return if possible
00160 *
00161       IF( N.EQ.0 )
00162      $   RETURN
00163 *
00164 *     Determine the block size for this environment.
00165 *
00166       NB = ILAENV( 1, 'CLAUUM', UPLO, N, -1, -1, -1 )
00167 *
00168       IF( NB.LE.1 .OR. NB.GE.N ) THEN
00169 *
00170 *        Use unblocked code
00171 *
00172          CALL CLAUU2( UPLO, N, A, LDA, INFO )
00173       ELSE
00174 *
00175 *        Use blocked code
00176 *
00177          IF( UPPER ) THEN
00178 *
00179 *           Compute the product U * U**H.
00180 *
00181             DO 10 I = 1, N, NB
00182                IB = MIN( NB, N-I+1 )
00183                CALL CTRMM( 'Right', 'Upper', 'Conjugate transpose',
00184      $                     'Non-unit', I-1, IB, CONE, A( I, I ), LDA,
00185      $                     A( 1, I ), LDA )
00186                CALL CLAUU2( 'Upper', IB, A( I, I ), LDA, INFO )
00187                IF( I+IB.LE.N ) THEN
00188                   CALL CGEMM( 'No transpose', 'Conjugate transpose',
00189      $                        I-1, IB, N-I-IB+1, CONE, A( 1, I+IB ),
00190      $                        LDA, A( I, I+IB ), LDA, CONE, A( 1, I ),
00191      $                        LDA )
00192                   CALL CHERK( 'Upper', 'No transpose', IB, N-I-IB+1,
00193      $                        ONE, A( I, I+IB ), LDA, ONE, A( I, I ),
00194      $                        LDA )
00195                END IF
00196    10       CONTINUE
00197          ELSE
00198 *
00199 *           Compute the product L**H * L.
00200 *
00201             DO 20 I = 1, N, NB
00202                IB = MIN( NB, N-I+1 )
00203                CALL CTRMM( 'Left', 'Lower', 'Conjugate transpose',
00204      $                     'Non-unit', IB, I-1, CONE, A( I, I ), LDA,
00205      $                     A( I, 1 ), LDA )
00206                CALL CLAUU2( 'Lower', IB, A( I, I ), LDA, INFO )
00207                IF( I+IB.LE.N ) THEN
00208                   CALL CGEMM( 'Conjugate transpose', 'No transpose', IB,
00209      $                        I-1, N-I-IB+1, CONE, A( I+IB, I ), LDA,
00210      $                        A( I+IB, 1 ), LDA, CONE, A( I, 1 ), LDA )
00211                   CALL CHERK( 'Lower', 'Conjugate transpose', IB,
00212      $                        N-I-IB+1, ONE, A( I+IB, I ), LDA, ONE,
00213      $                        A( I, I ), LDA )
00214                END IF
00215    20       CONTINUE
00216          END IF
00217       END IF
00218 *
00219       RETURN
00220 *
00221 *     End of CLAUUM
00222 *
00223       END
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