LAPACK  3.4.1
LAPACK: Linear Algebra PACKage
zunmhr.f
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00001 *> \brief \b ZUNMHR
00002 *
00003 *  =========== DOCUMENTATION ===========
00004 *
00005 * Online html documentation available at 
00006 *            http://www.netlib.org/lapack/explore-html/ 
00007 *
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00009 *> Download ZUNMHR + dependencies 
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00015 *> [TXT]</a>
00016 *> \endhtmlonly 
00017 *
00018 *  Definition:
00019 *  ===========
00020 *
00021 *       SUBROUTINE ZUNMHR( SIDE, TRANS, M, N, ILO, IHI, A, LDA, TAU, C,
00022 *                          LDC, WORK, LWORK, INFO )
00023 * 
00024 *       .. Scalar Arguments ..
00025 *       CHARACTER          SIDE, TRANS
00026 *       INTEGER            IHI, ILO, INFO, LDA, LDC, LWORK, M, N
00027 *       ..
00028 *       .. Array Arguments ..
00029 *       COMPLEX*16         A( LDA, * ), C( LDC, * ), TAU( * ), WORK( * )
00030 *       ..
00031 *  
00032 *
00033 *> \par Purpose:
00034 *  =============
00035 *>
00036 *> \verbatim
00037 *>
00038 *> ZUNMHR overwrites the general complex M-by-N matrix C with
00039 *>
00040 *>                 SIDE = 'L'     SIDE = 'R'
00041 *> TRANS = 'N':      Q * C          C * Q
00042 *> TRANS = 'C':      Q**H * C       C * Q**H
00043 *>
00044 *> where Q is a complex unitary matrix of order nq, with nq = m if
00045 *> SIDE = 'L' and nq = n if SIDE = 'R'. Q is defined as the product of
00046 *> IHI-ILO elementary reflectors, as returned by ZGEHRD:
00047 *>
00048 *> Q = H(ilo) H(ilo+1) . . . H(ihi-1).
00049 *> \endverbatim
00050 *
00051 *  Arguments:
00052 *  ==========
00053 *
00054 *> \param[in] SIDE
00055 *> \verbatim
00056 *>          SIDE is CHARACTER*1
00057 *>          = 'L': apply Q or Q**H from the Left;
00058 *>          = 'R': apply Q or Q**H from the Right.
00059 *> \endverbatim
00060 *>
00061 *> \param[in] TRANS
00062 *> \verbatim
00063 *>          TRANS is CHARACTER*1
00064 *>          = 'N': apply Q  (No transpose)
00065 *>          = 'C': apply Q**H (Conjugate transpose)
00066 *> \endverbatim
00067 *>
00068 *> \param[in] M
00069 *> \verbatim
00070 *>          M is INTEGER
00071 *>          The number of rows of the matrix C. M >= 0.
00072 *> \endverbatim
00073 *>
00074 *> \param[in] N
00075 *> \verbatim
00076 *>          N is INTEGER
00077 *>          The number of columns of the matrix C. N >= 0.
00078 *> \endverbatim
00079 *>
00080 *> \param[in] ILO
00081 *> \verbatim
00082 *>          ILO is INTEGER
00083 *> \endverbatim
00084 *>
00085 *> \param[in] IHI
00086 *> \verbatim
00087 *>          IHI is INTEGER
00088 *>
00089 *>          ILO and IHI must have the same values as in the previous call
00090 *>          of ZGEHRD. Q is equal to the unit matrix except in the
00091 *>          submatrix Q(ilo+1:ihi,ilo+1:ihi).
00092 *>          If SIDE = 'L', then 1 <= ILO <= IHI <= M, if M > 0, and
00093 *>          ILO = 1 and IHI = 0, if M = 0;
00094 *>          if SIDE = 'R', then 1 <= ILO <= IHI <= N, if N > 0, and
00095 *>          ILO = 1 and IHI = 0, if N = 0.
00096 *> \endverbatim
00097 *>
00098 *> \param[in] A
00099 *> \verbatim
00100 *>          A is COMPLEX*16 array, dimension
00101 *>                               (LDA,M) if SIDE = 'L'
00102 *>                               (LDA,N) if SIDE = 'R'
00103 *>          The vectors which define the elementary reflectors, as
00104 *>          returned by ZGEHRD.
00105 *> \endverbatim
00106 *>
00107 *> \param[in] LDA
00108 *> \verbatim
00109 *>          LDA is INTEGER
00110 *>          The leading dimension of the array A.
00111 *>          LDA >= max(1,M) if SIDE = 'L'; LDA >= max(1,N) if SIDE = 'R'.
00112 *> \endverbatim
00113 *>
00114 *> \param[in] TAU
00115 *> \verbatim
00116 *>          TAU is COMPLEX*16 array, dimension
00117 *>                               (M-1) if SIDE = 'L'
00118 *>                               (N-1) if SIDE = 'R'
00119 *>          TAU(i) must contain the scalar factor of the elementary
00120 *>          reflector H(i), as returned by ZGEHRD.
00121 *> \endverbatim
00122 *>
00123 *> \param[in,out] C
00124 *> \verbatim
00125 *>          C is COMPLEX*16 array, dimension (LDC,N)
00126 *>          On entry, the M-by-N matrix C.
00127 *>          On exit, C is overwritten by Q*C or Q**H*C or C*Q**H or C*Q.
00128 *> \endverbatim
00129 *>
00130 *> \param[in] LDC
00131 *> \verbatim
00132 *>          LDC is INTEGER
00133 *>          The leading dimension of the array C. LDC >= max(1,M).
00134 *> \endverbatim
00135 *>
00136 *> \param[out] WORK
00137 *> \verbatim
00138 *>          WORK is COMPLEX*16 array, dimension (MAX(1,LWORK))
00139 *>          On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
00140 *> \endverbatim
00141 *>
00142 *> \param[in] LWORK
00143 *> \verbatim
00144 *>          LWORK is INTEGER
00145 *>          The dimension of the array WORK.
00146 *>          If SIDE = 'L', LWORK >= max(1,N);
00147 *>          if SIDE = 'R', LWORK >= max(1,M).
00148 *>          For optimum performance LWORK >= N*NB if SIDE = 'L', and
00149 *>          LWORK >= M*NB if SIDE = 'R', where NB is the optimal
00150 *>          blocksize.
00151 *>
00152 *>          If LWORK = -1, then a workspace query is assumed; the routine
00153 *>          only calculates the optimal size of the WORK array, returns
00154 *>          this value as the first entry of the WORK array, and no error
00155 *>          message related to LWORK is issued by XERBLA.
00156 *> \endverbatim
00157 *>
00158 *> \param[out] INFO
00159 *> \verbatim
00160 *>          INFO is INTEGER
00161 *>          = 0:  successful exit
00162 *>          < 0:  if INFO = -i, the i-th argument had an illegal value
00163 *> \endverbatim
00164 *
00165 *  Authors:
00166 *  ========
00167 *
00168 *> \author Univ. of Tennessee 
00169 *> \author Univ. of California Berkeley 
00170 *> \author Univ. of Colorado Denver 
00171 *> \author NAG Ltd. 
00172 *
00173 *> \date November 2011
00174 *
00175 *> \ingroup complex16OTHERcomputational
00176 *
00177 *  =====================================================================
00178       SUBROUTINE ZUNMHR( SIDE, TRANS, M, N, ILO, IHI, A, LDA, TAU, C,
00179      $                   LDC, WORK, LWORK, INFO )
00180 *
00181 *  -- LAPACK computational routine (version 3.4.0) --
00182 *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
00183 *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
00184 *     November 2011
00185 *
00186 *     .. Scalar Arguments ..
00187       CHARACTER          SIDE, TRANS
00188       INTEGER            IHI, ILO, INFO, LDA, LDC, LWORK, M, N
00189 *     ..
00190 *     .. Array Arguments ..
00191       COMPLEX*16         A( LDA, * ), C( LDC, * ), TAU( * ), WORK( * )
00192 *     ..
00193 *
00194 *  =====================================================================
00195 *
00196 *     .. Local Scalars ..
00197       LOGICAL            LEFT, LQUERY
00198       INTEGER            I1, I2, IINFO, LWKOPT, MI, NB, NH, NI, NQ, NW
00199 *     ..
00200 *     .. External Functions ..
00201       LOGICAL            LSAME
00202       INTEGER            ILAENV
00203       EXTERNAL           LSAME, ILAENV
00204 *     ..
00205 *     .. External Subroutines ..
00206       EXTERNAL           XERBLA, ZUNMQR
00207 *     ..
00208 *     .. Intrinsic Functions ..
00209       INTRINSIC          MAX, MIN
00210 *     ..
00211 *     .. Executable Statements ..
00212 *
00213 *     Test the input arguments
00214 *
00215       INFO = 0
00216       NH = IHI - ILO
00217       LEFT = LSAME( SIDE, 'L' )
00218       LQUERY = ( LWORK.EQ.-1 )
00219 *
00220 *     NQ is the order of Q and NW is the minimum dimension of WORK
00221 *
00222       IF( LEFT ) THEN
00223          NQ = M
00224          NW = N
00225       ELSE
00226          NQ = N
00227          NW = M
00228       END IF
00229       IF( .NOT.LEFT .AND. .NOT.LSAME( SIDE, 'R' ) ) THEN
00230          INFO = -1
00231       ELSE IF( .NOT.LSAME( TRANS, 'N' ) .AND. .NOT.LSAME( TRANS, 'C' ) )
00232      $          THEN
00233          INFO = -2
00234       ELSE IF( M.LT.0 ) THEN
00235          INFO = -3
00236       ELSE IF( N.LT.0 ) THEN
00237          INFO = -4
00238       ELSE IF( ILO.LT.1 .OR. ILO.GT.MAX( 1, NQ ) ) THEN
00239          INFO = -5
00240       ELSE IF( IHI.LT.MIN( ILO, NQ ) .OR. IHI.GT.NQ ) THEN
00241          INFO = -6
00242       ELSE IF( LDA.LT.MAX( 1, NQ ) ) THEN
00243          INFO = -8
00244       ELSE IF( LDC.LT.MAX( 1, M ) ) THEN
00245          INFO = -11
00246       ELSE IF( LWORK.LT.MAX( 1, NW ) .AND. .NOT.LQUERY ) THEN
00247          INFO = -13
00248       END IF
00249 *
00250       IF( INFO.EQ.0 ) THEN
00251          IF( LEFT ) THEN
00252             NB = ILAENV( 1, 'ZUNMQR', SIDE // TRANS, NH, N, NH, -1 )
00253          ELSE
00254             NB = ILAENV( 1, 'ZUNMQR', SIDE // TRANS, M, NH, NH, -1 )
00255          END IF
00256          LWKOPT = MAX( 1, NW )*NB
00257          WORK( 1 ) = LWKOPT
00258       END IF
00259 *
00260       IF( INFO.NE.0 ) THEN
00261          CALL XERBLA( 'ZUNMHR', -INFO )
00262          RETURN
00263       ELSE IF( LQUERY ) THEN
00264          RETURN
00265       END IF
00266 *
00267 *     Quick return if possible
00268 *
00269       IF( M.EQ.0 .OR. N.EQ.0 .OR. NH.EQ.0 ) THEN
00270          WORK( 1 ) = 1
00271          RETURN
00272       END IF
00273 *
00274       IF( LEFT ) THEN
00275          MI = NH
00276          NI = N
00277          I1 = ILO + 1
00278          I2 = 1
00279       ELSE
00280          MI = M
00281          NI = NH
00282          I1 = 1
00283          I2 = ILO + 1
00284       END IF
00285 *
00286       CALL ZUNMQR( SIDE, TRANS, MI, NI, NH, A( ILO+1, ILO ), LDA,
00287      $             TAU( ILO ), C( I1, I2 ), LDC, WORK, LWORK, IINFO )
00288 *
00289       WORK( 1 ) = LWKOPT
00290       RETURN
00291 *
00292 *     End of ZUNMHR
00293 *
00294       END
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