136 SUBROUTINE cgelqf( M, N, A, LDA, TAU, WORK, LWORK, INFO )
144 INTEGER info, lda, lwork, m, n
147 COMPLEX a( lda, * ), tau( * ), work( * )
154 INTEGER i, ib, iinfo, iws, k, ldwork, lwkopt, nb,
172 nb =
ilaenv( 1,
'CGELQF',
' ', m, n, -1, -1 )
175 lquery = ( lwork.EQ.-1 )
178 ELSE IF( n.LT.0 )
THEN
180 ELSE IF( lda.LT.max( 1, m ) )
THEN
182 ELSE IF( lwork.LT.max( 1, m ) .AND. .NOT.lquery )
THEN
186 CALL
xerbla(
'CGELQF', -info )
188 ELSE IF( lquery )
THEN
203 IF( nb.GT.1 .AND. nb.LT.k )
THEN
207 nx = max( 0,
ilaenv( 3,
'CGELQF',
' ', m, n, -1, -1 ) )
214 IF( lwork.LT.iws )
THEN
220 nbmin = max( 2,
ilaenv( 2,
'CGELQF',
' ', m, n, -1,
226 IF( nb.GE.nbmin .AND. nb.LT.k .AND. nx.LT.k )
THEN
230 DO 10 i = 1, k - nx, nb
231 ib = min( k-i+1, nb )
236 CALL
cgelq2( ib, n-i+1, a( i, i ), lda, tau( i ), work,
243 CALL
clarft(
'Forward',
'Rowwise', n-i+1, ib, a( i, i ),
244 $ lda, tau( i ), work, ldwork )
248 CALL
clarfb(
'Right',
'No transpose',
'Forward',
249 $
'Rowwise', m-i-ib+1, n-i+1, ib, a( i, i ),
250 $ lda, work, ldwork, a( i+ib, i ), lda,
251 $ work( ib+1 ), ldwork )
261 $ CALL
cgelq2( m-i+1, n-i+1, a( i, i ), lda, tau( i ), work,
subroutine clarfb(SIDE, TRANS, DIRECT, STOREV, M, N, K, V, LDV, T, LDT, C, LDC, WORK, LDWORK)
CLARFB applies a block reflector or its conjugate-transpose to a general rectangular matrix...
subroutine xerbla(SRNAME, INFO)
XERBLA
subroutine clarft(DIRECT, STOREV, N, K, V, LDV, TAU, T, LDT)
CLARFT forms the triangular factor T of a block reflector H = I - vtvH
INTEGER function ilaenv(ISPEC, NAME, OPTS, N1, N2, N3, N4)
subroutine cgelqf(M, N, A, LDA, TAU, WORK, LWORK, INFO)
CGELQF
subroutine cgelq2(M, N, A, LDA, TAU, WORK, INFO)
CGELQ2 computes the LQ factorization of a general rectangular matrix using an unblocked algorithm...