LAPACK  3.4.1
LAPACK: Linear Algebra PACKage
cunmtr.f
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00001 *> \brief \b CUNMTR
00002 *
00003 *  =========== DOCUMENTATION ===========
00004 *
00005 * Online html documentation available at 
00006 *            http://www.netlib.org/lapack/explore-html/ 
00007 *
00008 *> \htmlonly
00009 *> Download CUNMTR + 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/cunmtr.f"> 
00015 *> [TXT]</a>
00016 *> \endhtmlonly 
00017 *
00018 *  Definition:
00019 *  ===========
00020 *
00021 *       SUBROUTINE CUNMTR( SIDE, UPLO, TRANS, M, N, A, LDA, TAU, C, LDC,
00022 *                          WORK, LWORK, INFO )
00023 * 
00024 *       .. Scalar Arguments ..
00025 *       CHARACTER          SIDE, TRANS, UPLO
00026 *       INTEGER            INFO, LDA, LDC, LWORK, M, N
00027 *       ..
00028 *       .. Array Arguments ..
00029 *       COMPLEX            A( LDA, * ), C( LDC, * ), TAU( * ),
00030 *      $                   WORK( * )
00031 *       ..
00032 *  
00033 *
00034 *> \par Purpose:
00035 *  =============
00036 *>
00037 *> \verbatim
00038 *>
00039 *> CUNMTR overwrites the general complex M-by-N matrix C with
00040 *>
00041 *>                 SIDE = 'L'     SIDE = 'R'
00042 *> TRANS = 'N':      Q * C          C * Q
00043 *> TRANS = 'C':      Q**H * C       C * Q**H
00044 *>
00045 *> where Q is a complex unitary matrix of order nq, with nq = m if
00046 *> SIDE = 'L' and nq = n if SIDE = 'R'. Q is defined as the product of
00047 *> nq-1 elementary reflectors, as returned by CHETRD:
00048 *>
00049 *> if UPLO = 'U', Q = H(nq-1) . . . H(2) H(1);
00050 *>
00051 *> if UPLO = 'L', Q = H(1) H(2) . . . H(nq-1).
00052 *> \endverbatim
00053 *
00054 *  Arguments:
00055 *  ==========
00056 *
00057 *> \param[in] SIDE
00058 *> \verbatim
00059 *>          SIDE is CHARACTER*1
00060 *>          = 'L': apply Q or Q**H from the Left;
00061 *>          = 'R': apply Q or Q**H from the Right.
00062 *> \endverbatim
00063 *>
00064 *> \param[in] UPLO
00065 *> \verbatim
00066 *>          UPLO is CHARACTER*1
00067 *>          = 'U': Upper triangle of A contains elementary reflectors
00068 *>                 from CHETRD;
00069 *>          = 'L': Lower triangle of A contains elementary reflectors
00070 *>                 from CHETRD.
00071 *> \endverbatim
00072 *>
00073 *> \param[in] TRANS
00074 *> \verbatim
00075 *>          TRANS is CHARACTER*1
00076 *>          = 'N':  No transpose, apply Q;
00077 *>          = 'C':  Conjugate transpose, apply Q**H.
00078 *> \endverbatim
00079 *>
00080 *> \param[in] M
00081 *> \verbatim
00082 *>          M is INTEGER
00083 *>          The number of rows of the matrix C. M >= 0.
00084 *> \endverbatim
00085 *>
00086 *> \param[in] N
00087 *> \verbatim
00088 *>          N is INTEGER
00089 *>          The number of columns of the matrix C. N >= 0.
00090 *> \endverbatim
00091 *>
00092 *> \param[in] A
00093 *> \verbatim
00094 *>          A is COMPLEX array, dimension
00095 *>                               (LDA,M) if SIDE = 'L'
00096 *>                               (LDA,N) if SIDE = 'R'
00097 *>          The vectors which define the elementary reflectors, as
00098 *>          returned by CHETRD.
00099 *> \endverbatim
00100 *>
00101 *> \param[in] LDA
00102 *> \verbatim
00103 *>          LDA is INTEGER
00104 *>          The leading dimension of the array A.
00105 *>          LDA >= max(1,M) if SIDE = 'L'; LDA >= max(1,N) if SIDE = 'R'.
00106 *> \endverbatim
00107 *>
00108 *> \param[in] TAU
00109 *> \verbatim
00110 *>          TAU is COMPLEX array, dimension
00111 *>                               (M-1) if SIDE = 'L'
00112 *>                               (N-1) if SIDE = 'R'
00113 *>          TAU(i) must contain the scalar factor of the elementary
00114 *>          reflector H(i), as returned by CHETRD.
00115 *> \endverbatim
00116 *>
00117 *> \param[in,out] C
00118 *> \verbatim
00119 *>          C is COMPLEX array, dimension (LDC,N)
00120 *>          On entry, the M-by-N matrix C.
00121 *>          On exit, C is overwritten by Q*C or Q**H*C or C*Q**H or C*Q.
00122 *> \endverbatim
00123 *>
00124 *> \param[in] LDC
00125 *> \verbatim
00126 *>          LDC is INTEGER
00127 *>          The leading dimension of the array C. LDC >= max(1,M).
00128 *> \endverbatim
00129 *>
00130 *> \param[out] WORK
00131 *> \verbatim
00132 *>          WORK is COMPLEX array, dimension (MAX(1,LWORK))
00133 *>          On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
00134 *> \endverbatim
00135 *>
00136 *> \param[in] LWORK
00137 *> \verbatim
00138 *>          LWORK is INTEGER
00139 *>          The dimension of the array WORK.
00140 *>          If SIDE = 'L', LWORK >= max(1,N);
00141 *>          if SIDE = 'R', LWORK >= max(1,M).
00142 *>          For optimum performance LWORK >= N*NB if SIDE = 'L', and
00143 *>          LWORK >=M*NB if SIDE = 'R', where NB is the optimal
00144 *>          blocksize.
00145 *>
00146 *>          If LWORK = -1, then a workspace query is assumed; the routine
00147 *>          only calculates the optimal size of the WORK array, returns
00148 *>          this value as the first entry of the WORK array, and no error
00149 *>          message related to LWORK is issued by XERBLA.
00150 *> \endverbatim
00151 *>
00152 *> \param[out] INFO
00153 *> \verbatim
00154 *>          INFO is INTEGER
00155 *>          = 0:  successful exit
00156 *>          < 0:  if INFO = -i, the i-th argument had an illegal value
00157 *> \endverbatim
00158 *
00159 *  Authors:
00160 *  ========
00161 *
00162 *> \author Univ. of Tennessee 
00163 *> \author Univ. of California Berkeley 
00164 *> \author Univ. of Colorado Denver 
00165 *> \author NAG Ltd. 
00166 *
00167 *> \date November 2011
00168 *
00169 *> \ingroup complexOTHERcomputational
00170 *
00171 *  =====================================================================
00172       SUBROUTINE CUNMTR( SIDE, UPLO, TRANS, M, N, A, LDA, TAU, C, LDC,
00173      $                   WORK, LWORK, INFO )
00174 *
00175 *  -- LAPACK computational routine (version 3.4.0) --
00176 *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
00177 *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
00178 *     November 2011
00179 *
00180 *     .. Scalar Arguments ..
00181       CHARACTER          SIDE, TRANS, UPLO
00182       INTEGER            INFO, LDA, LDC, LWORK, M, N
00183 *     ..
00184 *     .. Array Arguments ..
00185       COMPLEX            A( LDA, * ), C( LDC, * ), TAU( * ),
00186      $                   WORK( * )
00187 *     ..
00188 *
00189 *  =====================================================================
00190 *
00191 *     .. Local Scalars ..
00192       LOGICAL            LEFT, LQUERY, UPPER
00193       INTEGER            I1, I2, IINFO, LWKOPT, MI, NB, NI, NQ, NW
00194 *     ..
00195 *     .. External Functions ..
00196       LOGICAL            LSAME
00197       INTEGER            ILAENV
00198       EXTERNAL           ILAENV, LSAME
00199 *     ..
00200 *     .. External Subroutines ..
00201       EXTERNAL           CUNMQL, CUNMQR, XERBLA
00202 *     ..
00203 *     .. Intrinsic Functions ..
00204       INTRINSIC          MAX
00205 *     ..
00206 *     .. Executable Statements ..
00207 *
00208 *     Test the input arguments
00209 *
00210       INFO = 0
00211       LEFT = LSAME( SIDE, 'L' )
00212       UPPER = LSAME( UPLO, 'U' )
00213       LQUERY = ( LWORK.EQ.-1 )
00214 *
00215 *     NQ is the order of Q and NW is the minimum dimension of WORK
00216 *
00217       IF( LEFT ) THEN
00218          NQ = M
00219          NW = N
00220       ELSE
00221          NQ = N
00222          NW = M
00223       END IF
00224       IF( .NOT.LEFT .AND. .NOT.LSAME( SIDE, 'R' ) ) THEN
00225          INFO = -1
00226       ELSE IF( .NOT.UPPER .AND. .NOT.LSAME( UPLO, 'L' ) ) THEN
00227          INFO = -2
00228       ELSE IF( .NOT.LSAME( TRANS, 'N' ) .AND. .NOT.LSAME( TRANS, 'C' ) )
00229      $          THEN
00230          INFO = -3
00231       ELSE IF( M.LT.0 ) THEN
00232          INFO = -4
00233       ELSE IF( N.LT.0 ) THEN
00234          INFO = -5
00235       ELSE IF( LDA.LT.MAX( 1, NQ ) ) THEN
00236          INFO = -7
00237       ELSE IF( LDC.LT.MAX( 1, M ) ) THEN
00238          INFO = -10
00239       ELSE IF( LWORK.LT.MAX( 1, NW ) .AND. .NOT.LQUERY ) THEN
00240          INFO = -12
00241       END IF
00242 *
00243       IF( INFO.EQ.0 ) THEN
00244          IF( UPPER ) THEN
00245             IF( LEFT ) THEN
00246                NB = ILAENV( 1, 'CUNMQL', SIDE // TRANS, M-1, N, M-1,
00247      $                      -1 )
00248             ELSE
00249                NB = ILAENV( 1, 'CUNMQL', SIDE // TRANS, M, N-1, N-1,
00250      $                      -1 )
00251             END IF
00252          ELSE
00253             IF( LEFT ) THEN
00254                NB = ILAENV( 1, 'CUNMQR', SIDE // TRANS, M-1, N, M-1,
00255      $                      -1 )
00256             ELSE
00257                NB = ILAENV( 1, 'CUNMQR', SIDE // TRANS, M, N-1, N-1,
00258      $                      -1 )
00259             END IF
00260          END IF
00261          LWKOPT = MAX( 1, NW )*NB
00262          WORK( 1 ) = LWKOPT
00263       END IF
00264 *
00265       IF( INFO.NE.0 ) THEN
00266          CALL XERBLA( 'CUNMTR', -INFO )
00267          RETURN
00268       ELSE IF( LQUERY ) THEN
00269          RETURN
00270       END IF
00271 *
00272 *     Quick return if possible
00273 *
00274       IF( M.EQ.0 .OR. N.EQ.0 .OR. NQ.EQ.1 ) THEN
00275          WORK( 1 ) = 1
00276          RETURN
00277       END IF
00278 *
00279       IF( LEFT ) THEN
00280          MI = M - 1
00281          NI = N
00282       ELSE
00283          MI = M
00284          NI = N - 1
00285       END IF
00286 *
00287       IF( UPPER ) THEN
00288 *
00289 *        Q was determined by a call to CHETRD with UPLO = 'U'
00290 *
00291          CALL CUNMQL( SIDE, TRANS, MI, NI, NQ-1, A( 1, 2 ), LDA, TAU, C,
00292      $                LDC, WORK, LWORK, IINFO )
00293       ELSE
00294 *
00295 *        Q was determined by a call to CHETRD with UPLO = 'L'
00296 *
00297          IF( LEFT ) THEN
00298             I1 = 2
00299             I2 = 1
00300          ELSE
00301             I1 = 1
00302             I2 = 2
00303          END IF
00304          CALL CUNMQR( SIDE, TRANS, MI, NI, NQ-1, A( 2, 1 ), LDA, TAU,
00305      $                C( I1, I2 ), LDC, WORK, LWORK, IINFO )
00306       END IF
00307       WORK( 1 ) = LWKOPT
00308       RETURN
00309 *
00310 *     End of CUNMTR
00311 *
00312       END
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