129 SUBROUTINE sorgrq( M, N, K, A, LDA, TAU, WORK, LWORK, INFO )
137 INTEGER INFO, K, LDA, LWORK, M, N
140 REAL A( lda, * ), TAU( * ), WORK( * )
147 parameter ( zero = 0.0e+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,
'SORGRQ',
' ', m, n, k, -1 )
189 IF( lwork.LT.max( 1, m ) .AND. .NOT.lquery )
THEN
195 CALL xerbla(
'SORGRQ', -info )
197 ELSE IF( lquery )
THEN
210 IF( nb.GT.1 .AND. nb.LT.k )
THEN
214 nx = max( 0, ilaenv( 3,
'SORGRQ',
' ', m, n, k, -1 ) )
221 IF( lwork.LT.iws )
THEN
227 nbmin = max( 2, ilaenv( 2,
'SORGRQ',
' ', 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 sorgr2( 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 slarft(
'Backward',
'Rowwise', n-k+i+ib-1, ib,
267 $ a( ii, 1 ), lda, tau( i ), work, ldwork )
271 CALL slarfb(
'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 sorgr2( 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 sorgr2(M, N, K, A, LDA, TAU, WORK, INFO)
SORGR2 generates all or part of the orthogonal matrix Q from an RQ factorization determined by sgerqf...
subroutine xerbla(SRNAME, INFO)
XERBLA
subroutine slarft(DIRECT, STOREV, N, K, V, LDV, TAU, T, LDT)
SLARFT forms the triangular factor T of a block reflector H = I - vtvH
subroutine slarfb(SIDE, TRANS, DIRECT, STOREV, M, N, K, V, LDV, T, LDT, C, LDC, WORK, LDWORK)
SLARFB applies a block reflector or its transpose to a general rectangular matrix.
subroutine sorgrq(M, N, K, A, LDA, TAU, WORK, LWORK, INFO)
SORGRQ