129 SUBROUTINE dorgrq( M, N, K, A, LDA, TAU, WORK, LWORK, INFO )
137 INTEGER INFO, K, LDA, LWORK, M, N
140 DOUBLE PRECISION A( lda, * ), TAU( * ), WORK( * )
146 DOUBLE PRECISION ZERO
147 parameter( zero = 0.0d+0 )
151 INTEGER I, IB, II, IINFO, IWS, J, KK, L, LDWORK,
152 $ lwkopt, nb, nbmin, nx
169 lquery = ( lwork.EQ.-1 )
172 ELSE IF( n.LT.m )
THEN
174 ELSE IF( k.LT.0 .OR. k.GT.m )
THEN
176 ELSE IF( lda.LT.max( 1, m ) )
THEN
184 nb = ilaenv( 1,
'DORGRQ',
' ', m, n, k, -1 )
189 IF( lwork.LT.max( 1, m ) .AND. .NOT.lquery )
THEN
195 CALL
xerbla(
'DORGRQ', -info )
197 ELSE IF( lquery )
THEN
210 IF( nb.GT.1 .AND. nb.LT.k )
THEN
214 nx = max( 0, ilaenv( 3,
'DORGRQ',
' ', m, n, k, -1 ) )
221 IF( lwork.LT.iws )
THEN
227 nbmin = max( 2, ilaenv( 2,
'DORGRQ',
' ', m, n, k, -1 ) )
232 IF( nb.GE.nbmin .AND. nb.LT.k .AND. nx.LT.k )
THEN
237 kk = min( k, ( ( k-nx+nb-1 ) / nb )*nb )
241 DO 20 j = n - kk + 1, n
252 CALL
dorgr2( m-kk, n-kk, k-kk, a, lda, tau, work, iinfo )
258 DO 50 i = k - kk + 1, k, nb
259 ib = min( nb, k-i+1 )
266 CALL
dlarft(
'Backward',
'Rowwise', n-k+i+ib-1, ib,
267 $ a( ii, 1 ), lda, tau( i ), work, ldwork )
271 CALL
dlarfb(
'Right',
'Transpose',
'Backward',
'Rowwise',
272 $ ii-1, n-k+i+ib-1, ib, a( ii, 1 ), lda, work,
273 $ ldwork, a, lda, work( ib+1 ), ldwork )
278 CALL
dorgr2( ib, n-k+i+ib-1, ib, a( ii, 1 ), lda, tau( i ),
283 DO 40 l = n - k + i + ib, n
284 DO 30 j = ii, ii + ib - 1
subroutine dlarft(DIRECT, STOREV, N, K, V, LDV, TAU, T, LDT)
DLARFT forms the triangular factor T of a block reflector H = I - vtvH
subroutine dlarfb(SIDE, TRANS, DIRECT, STOREV, M, N, K, V, LDV, T, LDT, C, LDC, WORK, LDWORK)
DLARFB applies a block reflector or its transpose to a general rectangular matrix.
subroutine xerbla(SRNAME, INFO)
XERBLA
subroutine dorgrq(M, N, K, A, LDA, TAU, WORK, LWORK, INFO)
DORGRQ
subroutine dorgr2(M, N, K, A, LDA, TAU, WORK, INFO)
DORGR2 generates all or part of the orthogonal matrix Q from an RQ factorization determined by sgerqf...