LAPACK  3.8.0
LAPACK: Linear Algebra PACKage

◆ cqrt03()

subroutine cqrt03 ( integer  M,
integer  N,
integer  K,
complex, dimension( lda, * )  AF,
complex, dimension( lda, * )  C,
complex, dimension( lda, * )  CC,
complex, dimension( lda, * )  Q,
integer  LDA,
complex, dimension( * )  TAU,
complex, dimension( lwork )  WORK,
integer  LWORK,
real, dimension( * )  RWORK,
real, dimension( * )  RESULT 
)

CQRT03

Purpose:
 CQRT03 tests CUNMQR, which computes Q*C, Q'*C, C*Q or C*Q'.

 CQRT03 compares the results of a call to CUNMQR with the results of
 forming Q explicitly by a call to CUNGQR and then performing matrix
 multiplication by a call to CGEMM.
Parameters
[in]M
          M is INTEGER
          The order of the orthogonal matrix Q.  M >= 0.
[in]N
          N is INTEGER
          The number of rows or columns of the matrix C; C is m-by-n if
          Q is applied from the left, or n-by-m if Q is applied from
          the right.  N >= 0.
[in]K
          K is INTEGER
          The number of elementary reflectors whose product defines the
          orthogonal matrix Q.  M >= K >= 0.
[in]AF
          AF is COMPLEX array, dimension (LDA,N)
          Details of the QR factorization of an m-by-n matrix, as
          returned by CGEQRF. See CGEQRF for further details.
[out]C
          C is COMPLEX array, dimension (LDA,N)
[out]CC
          CC is COMPLEX array, dimension (LDA,N)
[out]Q
          Q is COMPLEX array, dimension (LDA,M)
[in]LDA
          LDA is INTEGER
          The leading dimension of the arrays AF, C, CC, and Q.
[in]TAU
          TAU is COMPLEX array, dimension (min(M,N))
          The scalar factors of the elementary reflectors corresponding
          to the QR factorization in AF.
[out]WORK
          WORK is COMPLEX array, dimension (LWORK)
[in]LWORK
          LWORK is INTEGER
          The length of WORK.  LWORK must be at least M, and should be
          M*NB, where NB is the blocksize for this environment.
[out]RWORK
          RWORK is REAL array, dimension (M)
[out]RESULT
          RESULT is REAL array, dimension (4)
          The test ratios compare two techniques for multiplying a
          random matrix C by an m-by-m orthogonal matrix Q.
          RESULT(1) = norm( Q*C - Q*C )  / ( M * norm(C) * EPS )
          RESULT(2) = norm( C*Q - C*Q )  / ( M * norm(C) * EPS )
          RESULT(3) = norm( Q'*C - Q'*C )/ ( M * norm(C) * EPS )
          RESULT(4) = norm( C*Q' - C*Q' )/ ( M * norm(C) * EPS )
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date
December 2016

Definition at line 138 of file cqrt03.f.

138 *
139 * -- LAPACK test routine (version 3.7.0) --
140 * -- LAPACK is a software package provided by Univ. of Tennessee, --
141 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
142 * December 2016
143 *
144 * .. Scalar Arguments ..
145  INTEGER k, lda, lwork, m, n
146 * ..
147 * .. Array Arguments ..
148  REAL result( * ), rwork( * )
149  COMPLEX af( lda, * ), c( lda, * ), cc( lda, * ),
150  $ q( lda, * ), tau( * ), work( lwork )
151 * ..
152 *
153 * =====================================================================
154 *
155 * .. Parameters ..
156  REAL zero, one
157  parameter( zero = 0.0e+0, one = 1.0e+0 )
158  COMPLEX rogue
159  parameter( rogue = ( -1.0e+10, -1.0e+10 ) )
160 * ..
161 * .. Local Scalars ..
162  CHARACTER side, trans
163  INTEGER info, iside, itrans, j, mc, nc
164  REAL cnorm, eps, resid
165 * ..
166 * .. External Functions ..
167  LOGICAL lsame
168  REAL clange, slamch
169  EXTERNAL lsame, clange, slamch
170 * ..
171 * .. External Subroutines ..
172  EXTERNAL cgemm, clacpy, clarnv, claset, cungqr, cunmqr
173 * ..
174 * .. Local Arrays ..
175  INTEGER iseed( 4 )
176 * ..
177 * .. Intrinsic Functions ..
178  INTRINSIC cmplx, max, real
179 * ..
180 * .. Scalars in Common ..
181  CHARACTER*32 srnamt
182 * ..
183 * .. Common blocks ..
184  COMMON / srnamc / srnamt
185 * ..
186 * .. Data statements ..
187  DATA iseed / 1988, 1989, 1990, 1991 /
188 * ..
189 * .. Executable Statements ..
190 *
191  eps = slamch( 'Epsilon' )
192 *
193 * Copy the first k columns of the factorization to the array Q
194 *
195  CALL claset( 'Full', m, m, rogue, rogue, q, lda )
196  CALL clacpy( 'Lower', m-1, k, af( 2, 1 ), lda, q( 2, 1 ), lda )
197 *
198 * Generate the m-by-m matrix Q
199 *
200  srnamt = 'CUNGQR'
201  CALL cungqr( m, m, k, q, lda, tau, work, lwork, info )
202 *
203  DO 30 iside = 1, 2
204  IF( iside.EQ.1 ) THEN
205  side = 'L'
206  mc = m
207  nc = n
208  ELSE
209  side = 'R'
210  mc = n
211  nc = m
212  END IF
213 *
214 * Generate MC by NC matrix C
215 *
216  DO 10 j = 1, nc
217  CALL clarnv( 2, iseed, mc, c( 1, j ) )
218  10 CONTINUE
219  cnorm = clange( '1', mc, nc, c, lda, rwork )
220  IF( cnorm.EQ.zero )
221  $ cnorm = one
222 *
223  DO 20 itrans = 1, 2
224  IF( itrans.EQ.1 ) THEN
225  trans = 'N'
226  ELSE
227  trans = 'C'
228  END IF
229 *
230 * Copy C
231 *
232  CALL clacpy( 'Full', mc, nc, c, lda, cc, lda )
233 *
234 * Apply Q or Q' to C
235 *
236  srnamt = 'CUNMQR'
237  CALL cunmqr( side, trans, mc, nc, k, af, lda, tau, cc, lda,
238  $ work, lwork, info )
239 *
240 * Form explicit product and subtract
241 *
242  IF( lsame( side, 'L' ) ) THEN
243  CALL cgemm( trans, 'No transpose', mc, nc, mc,
244  $ cmplx( -one ), q, lda, c, lda, cmplx( one ),
245  $ cc, lda )
246  ELSE
247  CALL cgemm( 'No transpose', trans, mc, nc, nc,
248  $ cmplx( -one ), c, lda, q, lda, cmplx( one ),
249  $ cc, lda )
250  END IF
251 *
252 * Compute error in the difference
253 *
254  resid = clange( '1', mc, nc, cc, lda, rwork )
255  result( ( iside-1 )*2+itrans ) = resid /
256  $ ( REAL( MAX( 1, M ) )*cnorm*eps )
257 *
258  20 CONTINUE
259  30 CONTINUE
260 *
261  RETURN
262 *
263 * End of CQRT03
264 *
subroutine claset(UPLO, M, N, ALPHA, BETA, A, LDA)
CLASET initializes the off-diagonal elements and the diagonal elements of a matrix to given values...
Definition: claset.f:108
subroutine cungqr(M, N, K, A, LDA, TAU, WORK, LWORK, INFO)
CUNGQR
Definition: cungqr.f:130
subroutine clarnv(IDIST, ISEED, N, X)
CLARNV returns a vector of random numbers from a uniform or normal distribution.
Definition: clarnv.f:101
real function clange(NORM, M, N, A, LDA, WORK)
CLANGE returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value ...
Definition: clange.f:117
logical function lsame(CA, CB)
LSAME
Definition: lsame.f:55
real function slamch(CMACH)
SLAMCH
Definition: slamch.f:69
subroutine clacpy(UPLO, M, N, A, LDA, B, LDB)
CLACPY copies all or part of one two-dimensional array to another.
Definition: clacpy.f:105
subroutine cunmqr(SIDE, TRANS, M, N, K, A, LDA, TAU, C, LDC, WORK, LWORK, INFO)
CUNMQR
Definition: cunmqr.f:170
subroutine cgemm(TRANSA, TRANSB, M, N, K, ALPHA, A, LDA, B, LDB, BETA, C, LDC)
CGEMM
Definition: cgemm.f:189
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