LAPACK  3.4.1
LAPACK: Linear Algebra PACKage
zqrt03.f
Go to the documentation of this file.
00001 *> \brief \b ZQRT03
00002 *
00003 *  =========== DOCUMENTATION ===========
00004 *
00005 * Online html documentation available at 
00006 *            http://www.netlib.org/lapack/explore-html/ 
00007 *
00008 *  Definition:
00009 *  ===========
00010 *
00011 *       SUBROUTINE ZQRT03( M, N, K, AF, C, CC, Q, LDA, TAU, WORK, LWORK,
00012 *                          RWORK, RESULT )
00013 * 
00014 *       .. Scalar Arguments ..
00015 *       INTEGER            K, LDA, LWORK, M, N
00016 *       ..
00017 *       .. Array Arguments ..
00018 *       DOUBLE PRECISION   RESULT( * ), RWORK( * )
00019 *       COMPLEX*16         AF( LDA, * ), C( LDA, * ), CC( LDA, * ),
00020 *      $                   Q( LDA, * ), TAU( * ), WORK( LWORK )
00021 *       ..
00022 *  
00023 *
00024 *> \par Purpose:
00025 *  =============
00026 *>
00027 *> \verbatim
00028 *>
00029 *> ZQRT03 tests ZUNMQR, which computes Q*C, Q'*C, C*Q or C*Q'.
00030 *>
00031 *> ZQRT03 compares the results of a call to ZUNMQR with the results of
00032 *> forming Q explicitly by a call to ZUNGQR and then performing matrix
00033 *> multiplication by a call to ZGEMM.
00034 *> \endverbatim
00035 *
00036 *  Arguments:
00037 *  ==========
00038 *
00039 *> \param[in] M
00040 *> \verbatim
00041 *>          M is INTEGER
00042 *>          The order of the orthogonal matrix Q.  M >= 0.
00043 *> \endverbatim
00044 *>
00045 *> \param[in] N
00046 *> \verbatim
00047 *>          N is INTEGER
00048 *>          The number of rows or columns of the matrix C; C is m-by-n if
00049 *>          Q is applied from the left, or n-by-m if Q is applied from
00050 *>          the right.  N >= 0.
00051 *> \endverbatim
00052 *>
00053 *> \param[in] K
00054 *> \verbatim
00055 *>          K is INTEGER
00056 *>          The number of elementary reflectors whose product defines the
00057 *>          orthogonal matrix Q.  M >= K >= 0.
00058 *> \endverbatim
00059 *>
00060 *> \param[in] AF
00061 *> \verbatim
00062 *>          AF is COMPLEX*16 array, dimension (LDA,N)
00063 *>          Details of the QR factorization of an m-by-n matrix, as
00064 *>          returnedby ZGEQRF. See CGEQRF for further details.
00065 *> \endverbatim
00066 *>
00067 *> \param[out] C
00068 *> \verbatim
00069 *>          C is COMPLEX*16 array, dimension (LDA,N)
00070 *> \endverbatim
00071 *>
00072 *> \param[out] CC
00073 *> \verbatim
00074 *>          CC is COMPLEX*16 array, dimension (LDA,N)
00075 *> \endverbatim
00076 *>
00077 *> \param[out] Q
00078 *> \verbatim
00079 *>          Q is COMPLEX*16 array, dimension (LDA,M)
00080 *> \endverbatim
00081 *>
00082 *> \param[in] LDA
00083 *> \verbatim
00084 *>          LDA is INTEGER
00085 *>          The leading dimension of the arrays AF, C, CC, and Q.
00086 *> \endverbatim
00087 *>
00088 *> \param[in] TAU
00089 *> \verbatim
00090 *>          TAU is COMPLEX*16 array, dimension (min(M,N))
00091 *>          The scalar factors of the elementary reflectors corresponding
00092 *>          to the QR factorization in AF.
00093 *> \endverbatim
00094 *>
00095 *> \param[out] WORK
00096 *> \verbatim
00097 *>          WORK is COMPLEX*16 array, dimension (LWORK)
00098 *> \endverbatim
00099 *>
00100 *> \param[in] LWORK
00101 *> \verbatim
00102 *>          LWORK is INTEGER
00103 *>          The length of WORK.  LWORK must be at least M, and should be
00104 *>          M*NB, where NB is the blocksize for this environment.
00105 *> \endverbatim
00106 *>
00107 *> \param[out] RWORK
00108 *> \verbatim
00109 *>          RWORK is DOUBLE PRECISION array, dimension (M)
00110 *> \endverbatim
00111 *>
00112 *> \param[out] RESULT
00113 *> \verbatim
00114 *>          RESULT is DOUBLE PRECISION array, dimension (4)
00115 *>          The test ratios compare two techniques for multiplying a
00116 *>          random matrix C by an m-by-m orthogonal matrix Q.
00117 *>          RESULT(1) = norm( Q*C - Q*C )  / ( M * norm(C) * EPS )
00118 *>          RESULT(2) = norm( C*Q - C*Q )  / ( M * norm(C) * EPS )
00119 *>          RESULT(3) = norm( Q'*C - Q'*C )/ ( M * norm(C) * EPS )
00120 *>          RESULT(4) = norm( C*Q' - C*Q' )/ ( M * norm(C) * EPS )
00121 *> \endverbatim
00122 *
00123 *  Authors:
00124 *  ========
00125 *
00126 *> \author Univ. of Tennessee 
00127 *> \author Univ. of California Berkeley 
00128 *> \author Univ. of Colorado Denver 
00129 *> \author NAG Ltd. 
00130 *
00131 *> \date November 2011
00132 *
00133 *> \ingroup complex16_lin
00134 *
00135 *  =====================================================================
00136       SUBROUTINE ZQRT03( M, N, K, AF, C, CC, Q, LDA, TAU, WORK, LWORK,
00137      $                   RWORK, RESULT )
00138 *
00139 *  -- LAPACK test routine (version 3.4.0) --
00140 *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
00141 *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
00142 *     November 2011
00143 *
00144 *     .. Scalar Arguments ..
00145       INTEGER            K, LDA, LWORK, M, N
00146 *     ..
00147 *     .. Array Arguments ..
00148       DOUBLE PRECISION   RESULT( * ), RWORK( * )
00149       COMPLEX*16         AF( LDA, * ), C( LDA, * ), CC( LDA, * ),
00150      $                   Q( LDA, * ), TAU( * ), WORK( LWORK )
00151 *     ..
00152 *
00153 *  =====================================================================
00154 *
00155 *     .. Parameters ..
00156       DOUBLE PRECISION   ZERO, ONE
00157       PARAMETER          ( ZERO = 0.0D+0, ONE = 1.0D+0 )
00158       COMPLEX*16         ROGUE
00159       PARAMETER          ( ROGUE = ( -1.0D+10, -1.0D+10 ) )
00160 *     ..
00161 *     .. Local Scalars ..
00162       CHARACTER          SIDE, TRANS
00163       INTEGER            INFO, ISIDE, ITRANS, J, MC, NC
00164       DOUBLE PRECISION   CNORM, EPS, RESID
00165 *     ..
00166 *     .. External Functions ..
00167       LOGICAL            LSAME
00168       DOUBLE PRECISION   DLAMCH, ZLANGE
00169       EXTERNAL           LSAME, DLAMCH, ZLANGE
00170 *     ..
00171 *     .. External Subroutines ..
00172       EXTERNAL           ZGEMM, ZLACPY, ZLARNV, ZLASET, ZUNGQR, ZUNMQR
00173 *     ..
00174 *     .. Local Arrays ..
00175       INTEGER            ISEED( 4 )
00176 *     ..
00177 *     .. Intrinsic Functions ..
00178       INTRINSIC          DBLE, DCMPLX, MAX
00179 *     ..
00180 *     .. Scalars in Common ..
00181       CHARACTER*32       SRNAMT
00182 *     ..
00183 *     .. Common blocks ..
00184       COMMON             / SRNAMC / SRNAMT
00185 *     ..
00186 *     .. Data statements ..
00187       DATA               ISEED / 1988, 1989, 1990, 1991 /
00188 *     ..
00189 *     .. Executable Statements ..
00190 *
00191       EPS = DLAMCH( 'Epsilon' )
00192 *
00193 *     Copy the first k columns of the factorization to the array Q
00194 *
00195       CALL ZLASET( 'Full', M, M, ROGUE, ROGUE, Q, LDA )
00196       CALL ZLACPY( 'Lower', M-1, K, AF( 2, 1 ), LDA, Q( 2, 1 ), LDA )
00197 *
00198 *     Generate the m-by-m matrix Q
00199 *
00200       SRNAMT = 'ZUNGQR'
00201       CALL ZUNGQR( M, M, K, Q, LDA, TAU, WORK, LWORK, INFO )
00202 *
00203       DO 30 ISIDE = 1, 2
00204          IF( ISIDE.EQ.1 ) THEN
00205             SIDE = 'L'
00206             MC = M
00207             NC = N
00208          ELSE
00209             SIDE = 'R'
00210             MC = N
00211             NC = M
00212          END IF
00213 *
00214 *        Generate MC by NC matrix C
00215 *
00216          DO 10 J = 1, NC
00217             CALL ZLARNV( 2, ISEED, MC, C( 1, J ) )
00218    10    CONTINUE
00219          CNORM = ZLANGE( '1', MC, NC, C, LDA, RWORK )
00220          IF( CNORM.EQ.ZERO )
00221      $      CNORM = ONE
00222 *
00223          DO 20 ITRANS = 1, 2
00224             IF( ITRANS.EQ.1 ) THEN
00225                TRANS = 'N'
00226             ELSE
00227                TRANS = 'C'
00228             END IF
00229 *
00230 *           Copy C
00231 *
00232             CALL ZLACPY( 'Full', MC, NC, C, LDA, CC, LDA )
00233 *
00234 *           Apply Q or Q' to C
00235 *
00236             SRNAMT = 'ZUNMQR'
00237             CALL ZUNMQR( SIDE, TRANS, MC, NC, K, AF, LDA, TAU, CC, LDA,
00238      $                   WORK, LWORK, INFO )
00239 *
00240 *           Form explicit product and subtract
00241 *
00242             IF( LSAME( SIDE, 'L' ) ) THEN
00243                CALL ZGEMM( TRANS, 'No transpose', MC, NC, MC,
00244      $                     DCMPLX( -ONE ), Q, LDA, C, LDA,
00245      $                     DCMPLX( ONE ), CC, LDA )
00246             ELSE
00247                CALL ZGEMM( 'No transpose', TRANS, MC, NC, NC,
00248      $                     DCMPLX( -ONE ), C, LDA, Q, LDA,
00249      $                     DCMPLX( ONE ), CC, LDA )
00250             END IF
00251 *
00252 *           Compute error in the difference
00253 *
00254             RESID = ZLANGE( '1', MC, NC, CC, LDA, RWORK )
00255             RESULT( ( ISIDE-1 )*2+ITRANS ) = RESID /
00256      $         ( DBLE( MAX( 1, M ) )*CNORM*EPS )
00257 *
00258    20    CONTINUE
00259    30 CONTINUE
00260 *
00261       RETURN
00262 *
00263 *     End of ZQRT03
00264 *
00265       END
 All Files Functions