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- *> \brief <b> SGESVD computes the singular value decomposition (SVD) for GE matrices</b>
- *
- * =========== DOCUMENTATION ===========
- *
- * Online html documentation available at
- * http://www.netlib.org/lapack/explore-html/
- *
- *> \htmlonly
- *> Download SGESVD + dependencies
- *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/sgesvd.f">
- *> [TGZ]</a>
- *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/sgesvd.f">
- *> [ZIP]</a>
- *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/sgesvd.f">
- *> [TXT]</a>
- *> \endhtmlonly
- *
- * Definition:
- * ===========
- *
- * SUBROUTINE SGESVD( JOBU, JOBVT, M, N, A, LDA, S, U, LDU, VT, LDVT,
- * WORK, LWORK, INFO )
- *
- * .. Scalar Arguments ..
- * CHARACTER JOBU, JOBVT
- * INTEGER INFO, LDA, LDU, LDVT, LWORK, M, N
- * ..
- * .. Array Arguments ..
- * REAL A( LDA, * ), S( * ), U( LDU, * ),
- * $ VT( LDVT, * ), WORK( * )
- * ..
- *
- *
- *> \par Purpose:
- * =============
- *>
- *> \verbatim
- *>
- *> SGESVD computes the singular value decomposition (SVD) of a real
- *> M-by-N matrix A, optionally computing the left and/or right singular
- *> vectors. The SVD is written
- *>
- *> A = U * SIGMA * transpose(V)
- *>
- *> where SIGMA is an M-by-N matrix which is zero except for its
- *> min(m,n) diagonal elements, U is an M-by-M orthogonal matrix, and
- *> V is an N-by-N orthogonal matrix. The diagonal elements of SIGMA
- *> are the singular values of A; they are real and non-negative, and
- *> are returned in descending order. The first min(m,n) columns of
- *> U and V are the left and right singular vectors of A.
- *>
- *> Note that the routine returns V**T, not V.
- *> \endverbatim
- *
- * Arguments:
- * ==========
- *
- *> \param[in] JOBU
- *> \verbatim
- *> JOBU is CHARACTER*1
- *> Specifies options for computing all or part of the matrix U:
- *> = 'A': all M columns of U are returned in array U:
- *> = 'S': the first min(m,n) columns of U (the left singular
- *> vectors) are returned in the array U;
- *> = 'O': the first min(m,n) columns of U (the left singular
- *> vectors) are overwritten on the array A;
- *> = 'N': no columns of U (no left singular vectors) are
- *> computed.
- *> \endverbatim
- *>
- *> \param[in] JOBVT
- *> \verbatim
- *> JOBVT is CHARACTER*1
- *> Specifies options for computing all or part of the matrix
- *> V**T:
- *> = 'A': all N rows of V**T are returned in the array VT;
- *> = 'S': the first min(m,n) rows of V**T (the right singular
- *> vectors) are returned in the array VT;
- *> = 'O': the first min(m,n) rows of V**T (the right singular
- *> vectors) are overwritten on the array A;
- *> = 'N': no rows of V**T (no right singular vectors) are
- *> computed.
- *>
- *> JOBVT and JOBU cannot both be 'O'.
- *> \endverbatim
- *>
- *> \param[in] M
- *> \verbatim
- *> M is INTEGER
- *> The number of rows of the input matrix A. M >= 0.
- *> \endverbatim
- *>
- *> \param[in] N
- *> \verbatim
- *> N is INTEGER
- *> The number of columns of the input matrix A. N >= 0.
- *> \endverbatim
- *>
- *> \param[in,out] A
- *> \verbatim
- *> A is REAL array, dimension (LDA,N)
- *> On entry, the M-by-N matrix A.
- *> On exit,
- *> if JOBU = 'O', A is overwritten with the first min(m,n)
- *> columns of U (the left singular vectors,
- *> stored columnwise);
- *> if JOBVT = 'O', A is overwritten with the first min(m,n)
- *> rows of V**T (the right singular vectors,
- *> stored rowwise);
- *> if JOBU .ne. 'O' and JOBVT .ne. 'O', the contents of A
- *> are destroyed.
- *> \endverbatim
- *>
- *> \param[in] LDA
- *> \verbatim
- *> LDA is INTEGER
- *> The leading dimension of the array A. LDA >= max(1,M).
- *> \endverbatim
- *>
- *> \param[out] S
- *> \verbatim
- *> S is REAL array, dimension (min(M,N))
- *> The singular values of A, sorted so that S(i) >= S(i+1).
- *> \endverbatim
- *>
- *> \param[out] U
- *> \verbatim
- *> U is REAL array, dimension (LDU,UCOL)
- *> (LDU,M) if JOBU = 'A' or (LDU,min(M,N)) if JOBU = 'S'.
- *> If JOBU = 'A', U contains the M-by-M orthogonal matrix U;
- *> if JOBU = 'S', U contains the first min(m,n) columns of U
- *> (the left singular vectors, stored columnwise);
- *> if JOBU = 'N' or 'O', U is not referenced.
- *> \endverbatim
- *>
- *> \param[in] LDU
- *> \verbatim
- *> LDU is INTEGER
- *> The leading dimension of the array U. LDU >= 1; if
- *> JOBU = 'S' or 'A', LDU >= M.
- *> \endverbatim
- *>
- *> \param[out] VT
- *> \verbatim
- *> VT is REAL array, dimension (LDVT,N)
- *> If JOBVT = 'A', VT contains the N-by-N orthogonal matrix
- *> V**T;
- *> if JOBVT = 'S', VT contains the first min(m,n) rows of
- *> V**T (the right singular vectors, stored rowwise);
- *> if JOBVT = 'N' or 'O', VT is not referenced.
- *> \endverbatim
- *>
- *> \param[in] LDVT
- *> \verbatim
- *> LDVT is INTEGER
- *> The leading dimension of the array VT. LDVT >= 1; if
- *> JOBVT = 'A', LDVT >= N; if JOBVT = 'S', LDVT >= min(M,N).
- *> \endverbatim
- *>
- *> \param[out] WORK
- *> \verbatim
- *> WORK is REAL array, dimension (MAX(1,LWORK))
- *> On exit, if INFO = 0, WORK(1) returns the optimal LWORK;
- *> if INFO > 0, WORK(2:MIN(M,N)) contains the unconverged
- *> superdiagonal elements of an upper bidiagonal matrix B
- *> whose diagonal is in S (not necessarily sorted). B
- *> satisfies A = U * B * VT, so it has the same singular values
- *> as A, and singular vectors related by U and VT.
- *> \endverbatim
- *>
- *> \param[in] LWORK
- *> \verbatim
- *> LWORK is INTEGER
- *> The dimension of the array WORK.
- *> LWORK >= MAX(1,5*MIN(M,N)) for the paths (see comments inside code):
- *> - PATH 1 (M much larger than N, JOBU='N')
- *> - PATH 1t (N much larger than M, JOBVT='N')
- *> LWORK >= MAX(1,3*MIN(M,N)+MAX(M,N),5*MIN(M,N)) for the other paths
- *> For good performance, LWORK should generally be larger.
- *>
- *> If LWORK = -1, then a workspace query is assumed; the routine
- *> only calculates the optimal size of the WORK array, returns
- *> this value as the first entry of the WORK array, and no error
- *> message related to LWORK is issued by XERBLA.
- *> \endverbatim
- *>
- *> \param[out] INFO
- *> \verbatim
- *> INFO is INTEGER
- *> = 0: successful exit.
- *> < 0: if INFO = -i, the i-th argument had an illegal value.
- *> > 0: if SBDSQR did not converge, INFO specifies how many
- *> superdiagonals of an intermediate bidiagonal form B
- *> did not converge to zero. See the description of WORK
- *> above for details.
- *> \endverbatim
- *
- * Authors:
- * ========
- *
- *> \author Univ. of Tennessee
- *> \author Univ. of California Berkeley
- *> \author Univ. of Colorado Denver
- *> \author NAG Ltd.
- *
- *> \ingroup gesvd
- *
- * =====================================================================
- SUBROUTINE SGESVD( JOBU, JOBVT, M, N, A, LDA, S, U, LDU, VT, LDVT,
- $ WORK, LWORK, INFO )
- *
- * -- LAPACK driver routine --
- * -- LAPACK is a software package provided by Univ. of Tennessee, --
- * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
- *
- * .. Scalar Arguments ..
- CHARACTER JOBU, JOBVT
- INTEGER INFO, LDA, LDU, LDVT, LWORK, M, N
- * ..
- * .. Array Arguments ..
- REAL A( LDA, * ), S( * ), U( LDU, * ),
- $ VT( LDVT, * ), WORK( * )
- * ..
- *
- * =====================================================================
- *
- * .. Parameters ..
- REAL ZERO, ONE
- PARAMETER ( ZERO = 0.0E0, ONE = 1.0E0 )
- * ..
- * .. Local Scalars ..
- LOGICAL LQUERY, WNTUA, WNTUAS, WNTUN, WNTUO, WNTUS,
- $ WNTVA, WNTVAS, WNTVN, WNTVO, WNTVS
- INTEGER BDSPAC, BLK, CHUNK, I, IE, IERR, IR, ISCL,
- $ ITAU, ITAUP, ITAUQ, IU, IWORK, LDWRKR, LDWRKU,
- $ MAXWRK, MINMN, MINWRK, MNTHR, NCU, NCVT, NRU,
- $ NRVT, WRKBL
- INTEGER LWORK_SGEQRF, LWORK_SORGQR_N, LWORK_SORGQR_M,
- $ LWORK_SGEBRD, LWORK_SORGBR_P, LWORK_SORGBR_Q,
- $ LWORK_SGELQF, LWORK_SORGLQ_N, LWORK_SORGLQ_M
- REAL ANRM, BIGNUM, EPS, SMLNUM
- * ..
- * .. Local Arrays ..
- REAL DUM( 1 )
- * ..
- * .. External Subroutines ..
- EXTERNAL SBDSQR, SGEBRD, SGELQF, SGEMM, SGEQRF, SLACPY,
- $ SLASCL, SLASET, SORGBR, SORGLQ, SORGQR, SORMBR,
- $ XERBLA
- * ..
- * .. External Functions ..
- LOGICAL LSAME
- INTEGER ILAENV
- REAL SLAMCH, SLANGE, SROUNDUP_LWORK
- EXTERNAL LSAME, ILAENV, SLAMCH, SLANGE, SROUNDUP_LWORK
- * ..
- * .. Intrinsic Functions ..
- INTRINSIC MAX, MIN, SQRT
- * ..
- * .. Executable Statements ..
- *
- * Test the input arguments
- *
- INFO = 0
- MINMN = MIN( M, N )
- WNTUA = LSAME( JOBU, 'A' )
- WNTUS = LSAME( JOBU, 'S' )
- WNTUAS = WNTUA .OR. WNTUS
- WNTUO = LSAME( JOBU, 'O' )
- WNTUN = LSAME( JOBU, 'N' )
- WNTVA = LSAME( JOBVT, 'A' )
- WNTVS = LSAME( JOBVT, 'S' )
- WNTVAS = WNTVA .OR. WNTVS
- WNTVO = LSAME( JOBVT, 'O' )
- WNTVN = LSAME( JOBVT, 'N' )
- LQUERY = ( LWORK.EQ.-1 )
- *
- IF( .NOT.( WNTUA .OR. WNTUS .OR. WNTUO .OR. WNTUN ) ) THEN
- INFO = -1
- ELSE IF( .NOT.( WNTVA .OR. WNTVS .OR. WNTVO .OR. WNTVN ) .OR.
- $ ( WNTVO .AND. WNTUO ) ) THEN
- INFO = -2
- ELSE IF( M.LT.0 ) THEN
- INFO = -3
- ELSE IF( N.LT.0 ) THEN
- INFO = -4
- ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
- INFO = -6
- ELSE IF( LDU.LT.1 .OR. ( WNTUAS .AND. LDU.LT.M ) ) THEN
- INFO = -9
- ELSE IF( LDVT.LT.1 .OR. ( WNTVA .AND. LDVT.LT.N ) .OR.
- $ ( WNTVS .AND. LDVT.LT.MINMN ) ) THEN
- INFO = -11
- END IF
- *
- * Compute workspace
- * (Note: Comments in the code beginning "Workspace:" describe the
- * minimal amount of workspace needed at that point in the code,
- * as well as the preferred amount for good performance.
- * NB refers to the optimal block size for the immediately
- * following subroutine, as returned by ILAENV.)
- *
- IF( INFO.EQ.0 ) THEN
- MINWRK = 1
- MAXWRK = 1
- IF( M.GE.N .AND. MINMN.GT.0 ) THEN
- *
- * Compute space needed for SBDSQR
- *
- MNTHR = ILAENV( 6, 'SGESVD', JOBU // JOBVT, M, N, 0, 0 )
- BDSPAC = 5*N
- * Compute space needed for SGEQRF
- CALL SGEQRF( M, N, A, LDA, DUM(1), DUM(1), -1, IERR )
- LWORK_SGEQRF = INT( DUM(1) )
- * Compute space needed for SORGQR
- CALL SORGQR( M, N, N, A, LDA, DUM(1), DUM(1), -1, IERR )
- LWORK_SORGQR_N = INT( DUM(1) )
- CALL SORGQR( M, M, N, A, LDA, DUM(1), DUM(1), -1, IERR )
- LWORK_SORGQR_M = INT( DUM(1) )
- * Compute space needed for SGEBRD
- CALL SGEBRD( N, N, A, LDA, S, DUM(1), DUM(1),
- $ DUM(1), DUM(1), -1, IERR )
- LWORK_SGEBRD = INT( DUM(1) )
- * Compute space needed for SORGBR P
- CALL SORGBR( 'P', N, N, N, A, LDA, DUM(1),
- $ DUM(1), -1, IERR )
- LWORK_SORGBR_P = INT( DUM(1) )
- * Compute space needed for SORGBR Q
- CALL SORGBR( 'Q', N, N, N, A, LDA, DUM(1),
- $ DUM(1), -1, IERR )
- LWORK_SORGBR_Q = INT( DUM(1) )
- *
- IF( M.GE.MNTHR ) THEN
- IF( WNTUN ) THEN
- *
- * Path 1 (M much larger than N, JOBU='N')
- *
- MAXWRK = N + LWORK_SGEQRF
- MAXWRK = MAX( MAXWRK, 3*N+LWORK_SGEBRD )
- IF( WNTVO .OR. WNTVAS )
- $ MAXWRK = MAX( MAXWRK, 3*N+LWORK_SORGBR_P )
- MAXWRK = MAX( MAXWRK, BDSPAC )
- MINWRK = MAX( 4*N, BDSPAC )
- ELSE IF( WNTUO .AND. WNTVN ) THEN
- *
- * Path 2 (M much larger than N, JOBU='O', JOBVT='N')
- *
- WRKBL = N + LWORK_SGEQRF
- WRKBL = MAX( WRKBL, N+LWORK_SORGQR_N )
- WRKBL = MAX( WRKBL, 3*N+LWORK_SGEBRD )
- WRKBL = MAX( WRKBL, 3*N+LWORK_SORGBR_Q )
- WRKBL = MAX( WRKBL, BDSPAC )
- MAXWRK = MAX( N*N+WRKBL, N*N+M*N+N )
- MINWRK = MAX( 3*N+M, BDSPAC )
- ELSE IF( WNTUO .AND. WNTVAS ) THEN
- *
- * Path 3 (M much larger than N, JOBU='O', JOBVT='S' or
- * 'A')
- *
- WRKBL = N + LWORK_SGEQRF
- WRKBL = MAX( WRKBL, N+LWORK_SORGQR_N )
- WRKBL = MAX( WRKBL, 3*N+LWORK_SGEBRD )
- WRKBL = MAX( WRKBL, 3*N+LWORK_SORGBR_Q )
- WRKBL = MAX( WRKBL, 3*N+LWORK_SORGBR_P )
- WRKBL = MAX( WRKBL, BDSPAC )
- MAXWRK = MAX( N*N+WRKBL, N*N+M*N+N )
- MINWRK = MAX( 3*N+M, BDSPAC )
- ELSE IF( WNTUS .AND. WNTVN ) THEN
- *
- * Path 4 (M much larger than N, JOBU='S', JOBVT='N')
- *
- WRKBL = N + LWORK_SGEQRF
- WRKBL = MAX( WRKBL, N+LWORK_SORGQR_N )
- WRKBL = MAX( WRKBL, 3*N+LWORK_SGEBRD )
- WRKBL = MAX( WRKBL, 3*N+LWORK_SORGBR_Q )
- WRKBL = MAX( WRKBL, BDSPAC )
- MAXWRK = N*N + WRKBL
- MINWRK = MAX( 3*N+M, BDSPAC )
- ELSE IF( WNTUS .AND. WNTVO ) THEN
- *
- * Path 5 (M much larger than N, JOBU='S', JOBVT='O')
- *
- WRKBL = N + LWORK_SGEQRF
- WRKBL = MAX( WRKBL, N+LWORK_SORGQR_N )
- WRKBL = MAX( WRKBL, 3*N+LWORK_SGEBRD )
- WRKBL = MAX( WRKBL, 3*N+LWORK_SORGBR_Q )
- WRKBL = MAX( WRKBL, 3*N+LWORK_SORGBR_P )
- WRKBL = MAX( WRKBL, BDSPAC )
- MAXWRK = 2*N*N + WRKBL
- MINWRK = MAX( 3*N+M, BDSPAC )
- ELSE IF( WNTUS .AND. WNTVAS ) THEN
- *
- * Path 6 (M much larger than N, JOBU='S', JOBVT='S' or
- * 'A')
- *
- WRKBL = N + LWORK_SGEQRF
- WRKBL = MAX( WRKBL, N+LWORK_SORGQR_N )
- WRKBL = MAX( WRKBL, 3*N+LWORK_SGEBRD )
- WRKBL = MAX( WRKBL, 3*N+LWORK_SORGBR_Q )
- WRKBL = MAX( WRKBL, 3*N+LWORK_SORGBR_P )
- WRKBL = MAX( WRKBL, BDSPAC )
- MAXWRK = N*N + WRKBL
- MINWRK = MAX( 3*N+M, BDSPAC )
- ELSE IF( WNTUA .AND. WNTVN ) THEN
- *
- * Path 7 (M much larger than N, JOBU='A', JOBVT='N')
- *
- WRKBL = N + LWORK_SGEQRF
- WRKBL = MAX( WRKBL, N+LWORK_SORGQR_M )
- WRKBL = MAX( WRKBL, 3*N+LWORK_SGEBRD )
- WRKBL = MAX( WRKBL, 3*N+LWORK_SORGBR_Q )
- WRKBL = MAX( WRKBL, BDSPAC )
- MAXWRK = N*N + WRKBL
- MINWRK = MAX( 3*N+M, BDSPAC )
- ELSE IF( WNTUA .AND. WNTVO ) THEN
- *
- * Path 8 (M much larger than N, JOBU='A', JOBVT='O')
- *
- WRKBL = N + LWORK_SGEQRF
- WRKBL = MAX( WRKBL, N+LWORK_SORGQR_M )
- WRKBL = MAX( WRKBL, 3*N+LWORK_SGEBRD )
- WRKBL = MAX( WRKBL, 3*N+LWORK_SORGBR_Q )
- WRKBL = MAX( WRKBL, 3*N+LWORK_SORGBR_P )
- WRKBL = MAX( WRKBL, BDSPAC )
- MAXWRK = 2*N*N + WRKBL
- MINWRK = MAX( 3*N+M, BDSPAC )
- ELSE IF( WNTUA .AND. WNTVAS ) THEN
- *
- * Path 9 (M much larger than N, JOBU='A', JOBVT='S' or
- * 'A')
- *
- WRKBL = N + LWORK_SGEQRF
- WRKBL = MAX( WRKBL, N+LWORK_SORGQR_M )
- WRKBL = MAX( WRKBL, 3*N+LWORK_SGEBRD )
- WRKBL = MAX( WRKBL, 3*N+LWORK_SORGBR_Q )
- WRKBL = MAX( WRKBL, 3*N+LWORK_SORGBR_P )
- WRKBL = MAX( WRKBL, BDSPAC )
- MAXWRK = N*N + WRKBL
- MINWRK = MAX( 3*N+M, BDSPAC )
- END IF
- ELSE
- *
- * Path 10 (M at least N, but not much larger)
- *
- CALL SGEBRD( M, N, A, LDA, S, DUM(1), DUM(1),
- $ DUM(1), DUM(1), -1, IERR )
- LWORK_SGEBRD = INT( DUM(1) )
- MAXWRK = 3*N + LWORK_SGEBRD
- IF( WNTUS .OR. WNTUO ) THEN
- CALL SORGBR( 'Q', M, N, N, A, LDA, DUM(1),
- $ DUM(1), -1, IERR )
- LWORK_SORGBR_Q = INT( DUM(1) )
- MAXWRK = MAX( MAXWRK, 3*N+LWORK_SORGBR_Q )
- END IF
- IF( WNTUA ) THEN
- CALL SORGBR( 'Q', M, M, N, A, LDA, DUM(1),
- $ DUM(1), -1, IERR )
- LWORK_SORGBR_Q = INT( DUM(1) )
- MAXWRK = MAX( MAXWRK, 3*N+LWORK_SORGBR_Q )
- END IF
- IF( .NOT.WNTVN ) THEN
- MAXWRK = MAX( MAXWRK, 3*N+LWORK_SORGBR_P )
- END IF
- MAXWRK = MAX( MAXWRK, BDSPAC )
- MINWRK = MAX( 3*N+M, BDSPAC )
- END IF
- ELSE IF( MINMN.GT.0 ) THEN
- *
- * Compute space needed for SBDSQR
- *
- MNTHR = ILAENV( 6, 'SGESVD', JOBU // JOBVT, M, N, 0, 0 )
- BDSPAC = 5*M
- * Compute space needed for SGELQF
- CALL SGELQF( M, N, A, LDA, DUM(1), DUM(1), -1, IERR )
- LWORK_SGELQF = INT( DUM(1) )
- * Compute space needed for SORGLQ
- CALL SORGLQ( N, N, M, DUM(1), N, DUM(1), DUM(1), -1, IERR )
- LWORK_SORGLQ_N = INT( DUM(1) )
- CALL SORGLQ( M, N, M, A, LDA, DUM(1), DUM(1), -1, IERR )
- LWORK_SORGLQ_M = INT( DUM(1) )
- * Compute space needed for SGEBRD
- CALL SGEBRD( M, M, A, LDA, S, DUM(1), DUM(1),
- $ DUM(1), DUM(1), -1, IERR )
- LWORK_SGEBRD = INT( DUM(1) )
- * Compute space needed for SORGBR P
- CALL SORGBR( 'P', M, M, M, A, N, DUM(1),
- $ DUM(1), -1, IERR )
- LWORK_SORGBR_P = INT( DUM(1) )
- * Compute space needed for SORGBR Q
- CALL SORGBR( 'Q', M, M, M, A, N, DUM(1),
- $ DUM(1), -1, IERR )
- LWORK_SORGBR_Q = INT( DUM(1) )
- IF( N.GE.MNTHR ) THEN
- IF( WNTVN ) THEN
- *
- * Path 1t(N much larger than M, JOBVT='N')
- *
- MAXWRK = M + LWORK_SGELQF
- MAXWRK = MAX( MAXWRK, 3*M+LWORK_SGEBRD )
- IF( WNTUO .OR. WNTUAS )
- $ MAXWRK = MAX( MAXWRK, 3*M+LWORK_SORGBR_Q )
- MAXWRK = MAX( MAXWRK, BDSPAC )
- MINWRK = MAX( 4*M, BDSPAC )
- ELSE IF( WNTVO .AND. WNTUN ) THEN
- *
- * Path 2t(N much larger than M, JOBU='N', JOBVT='O')
- *
- WRKBL = M + LWORK_SGELQF
- WRKBL = MAX( WRKBL, M+LWORK_SORGLQ_M )
- WRKBL = MAX( WRKBL, 3*M+LWORK_SGEBRD )
- WRKBL = MAX( WRKBL, 3*M+LWORK_SORGBR_P )
- WRKBL = MAX( WRKBL, BDSPAC )
- MAXWRK = MAX( M*M+WRKBL, M*M+M*N+M )
- MINWRK = MAX( 3*M+N, BDSPAC )
- ELSE IF( WNTVO .AND. WNTUAS ) THEN
- *
- * Path 3t(N much larger than M, JOBU='S' or 'A',
- * JOBVT='O')
- *
- WRKBL = M + LWORK_SGELQF
- WRKBL = MAX( WRKBL, M+LWORK_SORGLQ_M )
- WRKBL = MAX( WRKBL, 3*M+LWORK_SGEBRD )
- WRKBL = MAX( WRKBL, 3*M+LWORK_SORGBR_P )
- WRKBL = MAX( WRKBL, 3*M+LWORK_SORGBR_Q )
- WRKBL = MAX( WRKBL, BDSPAC )
- MAXWRK = MAX( M*M+WRKBL, M*M+M*N+M )
- MINWRK = MAX( 3*M+N, BDSPAC )
- ELSE IF( WNTVS .AND. WNTUN ) THEN
- *
- * Path 4t(N much larger than M, JOBU='N', JOBVT='S')
- *
- WRKBL = M + LWORK_SGELQF
- WRKBL = MAX( WRKBL, M+LWORK_SORGLQ_M )
- WRKBL = MAX( WRKBL, 3*M+LWORK_SGEBRD )
- WRKBL = MAX( WRKBL, 3*M+LWORK_SORGBR_P )
- WRKBL = MAX( WRKBL, BDSPAC )
- MAXWRK = M*M + WRKBL
- MINWRK = MAX( 3*M+N, BDSPAC )
- ELSE IF( WNTVS .AND. WNTUO ) THEN
- *
- * Path 5t(N much larger than M, JOBU='O', JOBVT='S')
- *
- WRKBL = M + LWORK_SGELQF
- WRKBL = MAX( WRKBL, M+LWORK_SORGLQ_M )
- WRKBL = MAX( WRKBL, 3*M+LWORK_SGEBRD )
- WRKBL = MAX( WRKBL, 3*M+LWORK_SORGBR_P )
- WRKBL = MAX( WRKBL, 3*M+LWORK_SORGBR_Q )
- WRKBL = MAX( WRKBL, BDSPAC )
- MAXWRK = 2*M*M + WRKBL
- MINWRK = MAX( 3*M+N, BDSPAC )
- MAXWRK = MAX( MAXWRK, MINWRK )
- ELSE IF( WNTVS .AND. WNTUAS ) THEN
- *
- * Path 6t(N much larger than M, JOBU='S' or 'A',
- * JOBVT='S')
- *
- WRKBL = M + LWORK_SGELQF
- WRKBL = MAX( WRKBL, M+LWORK_SORGLQ_M )
- WRKBL = MAX( WRKBL, 3*M+LWORK_SGEBRD )
- WRKBL = MAX( WRKBL, 3*M+LWORK_SORGBR_P )
- WRKBL = MAX( WRKBL, 3*M+LWORK_SORGBR_Q )
- WRKBL = MAX( WRKBL, BDSPAC )
- MAXWRK = M*M + WRKBL
- MINWRK = MAX( 3*M+N, BDSPAC )
- ELSE IF( WNTVA .AND. WNTUN ) THEN
- *
- * Path 7t(N much larger than M, JOBU='N', JOBVT='A')
- *
- WRKBL = M + LWORK_SGELQF
- WRKBL = MAX( WRKBL, M+LWORK_SORGLQ_N )
- WRKBL = MAX( WRKBL, 3*M+LWORK_SGEBRD )
- WRKBL = MAX( WRKBL, 3*M+LWORK_SORGBR_P )
- WRKBL = MAX( WRKBL, BDSPAC )
- MAXWRK = M*M + WRKBL
- MINWRK = MAX( 3*M+N, BDSPAC )
- ELSE IF( WNTVA .AND. WNTUO ) THEN
- *
- * Path 8t(N much larger than M, JOBU='O', JOBVT='A')
- *
- WRKBL = M + LWORK_SGELQF
- WRKBL = MAX( WRKBL, M+LWORK_SORGLQ_N )
- WRKBL = MAX( WRKBL, 3*M+LWORK_SGEBRD )
- WRKBL = MAX( WRKBL, 3*M+LWORK_SORGBR_P )
- WRKBL = MAX( WRKBL, 3*M+LWORK_SORGBR_Q )
- WRKBL = MAX( WRKBL, BDSPAC )
- MAXWRK = 2*M*M + WRKBL
- MINWRK = MAX( 3*M+N, BDSPAC )
- ELSE IF( WNTVA .AND. WNTUAS ) THEN
- *
- * Path 9t(N much larger than M, JOBU='S' or 'A',
- * JOBVT='A')
- *
- WRKBL = M + LWORK_SGELQF
- WRKBL = MAX( WRKBL, M+LWORK_SORGLQ_N )
- WRKBL = MAX( WRKBL, 3*M+LWORK_SGEBRD )
- WRKBL = MAX( WRKBL, 3*M+LWORK_SORGBR_P )
- WRKBL = MAX( WRKBL, 3*M+LWORK_SORGBR_Q )
- WRKBL = MAX( WRKBL, BDSPAC )
- MAXWRK = M*M + WRKBL
- MINWRK = MAX( 3*M+N, BDSPAC )
- END IF
- ELSE
- *
- * Path 10t(N greater than M, but not much larger)
- *
- CALL SGEBRD( M, N, A, LDA, S, DUM(1), DUM(1),
- $ DUM(1), DUM(1), -1, IERR )
- LWORK_SGEBRD = INT( DUM(1) )
- MAXWRK = 3*M + LWORK_SGEBRD
- IF( WNTVS .OR. WNTVO ) THEN
- * Compute space needed for SORGBR P
- CALL SORGBR( 'P', M, N, M, A, N, DUM(1),
- $ DUM(1), -1, IERR )
- LWORK_SORGBR_P = INT( DUM(1) )
- MAXWRK = MAX( MAXWRK, 3*M+LWORK_SORGBR_P )
- END IF
- IF( WNTVA ) THEN
- CALL SORGBR( 'P', N, N, M, A, N, DUM(1),
- $ DUM(1), -1, IERR )
- LWORK_SORGBR_P = INT( DUM(1) )
- MAXWRK = MAX( MAXWRK, 3*M+LWORK_SORGBR_P )
- END IF
- IF( .NOT.WNTUN ) THEN
- MAXWRK = MAX( MAXWRK, 3*M+LWORK_SORGBR_Q )
- END IF
- MAXWRK = MAX( MAXWRK, BDSPAC )
- MINWRK = MAX( 3*M+N, BDSPAC )
- END IF
- END IF
- MAXWRK = MAX( MAXWRK, MINWRK )
- WORK( 1 ) = SROUNDUP_LWORK(MAXWRK)
- *
- IF( LWORK.LT.MINWRK .AND. .NOT.LQUERY ) THEN
- INFO = -13
- END IF
- END IF
- *
- IF( INFO.NE.0 ) THEN
- CALL XERBLA( 'SGESVD', -INFO )
- RETURN
- ELSE IF( LQUERY ) THEN
- RETURN
- END IF
- *
- * Quick return if possible
- *
- IF( M.EQ.0 .OR. N.EQ.0 ) THEN
- RETURN
- END IF
- *
- * Get machine constants
- *
- EPS = SLAMCH( 'P' )
- SMLNUM = SQRT( SLAMCH( 'S' ) ) / EPS
- BIGNUM = ONE / SMLNUM
- *
- * Scale A if max element outside range [SMLNUM,BIGNUM]
- *
- ANRM = SLANGE( 'M', M, N, A, LDA, DUM )
- ISCL = 0
- IF( ANRM.GT.ZERO .AND. ANRM.LT.SMLNUM ) THEN
- ISCL = 1
- CALL SLASCL( 'G', 0, 0, ANRM, SMLNUM, M, N, A, LDA, IERR )
- ELSE IF( ANRM.GT.BIGNUM ) THEN
- ISCL = 1
- CALL SLASCL( 'G', 0, 0, ANRM, BIGNUM, M, N, A, LDA, IERR )
- END IF
- *
- IF( M.GE.N ) THEN
- *
- * A has at least as many rows as columns. If A has sufficiently
- * more rows than columns, first reduce using the QR
- * decomposition (if sufficient workspace available)
- *
- IF( M.GE.MNTHR ) THEN
- *
- IF( WNTUN ) THEN
- *
- * Path 1 (M much larger than N, JOBU='N')
- * No left singular vectors to be computed
- *
- ITAU = 1
- IWORK = ITAU + N
- *
- * Compute A=Q*R
- * (Workspace: need 2*N, prefer N+N*NB)
- *
- CALL SGEQRF( M, N, A, LDA, WORK( ITAU ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- *
- * Zero out below R
- *
- IF( N .GT. 1 ) THEN
- CALL SLASET( 'L', N-1, N-1, ZERO, ZERO, A( 2, 1 ),
- $ LDA )
- END IF
- IE = 1
- ITAUQ = IE + N
- ITAUP = ITAUQ + N
- IWORK = ITAUP + N
- *
- * Bidiagonalize R in A
- * (Workspace: need 4*N, prefer 3*N+2*N*NB)
- *
- CALL SGEBRD( N, N, A, LDA, S, WORK( IE ), WORK( ITAUQ ),
- $ WORK( ITAUP ), WORK( IWORK ), LWORK-IWORK+1,
- $ IERR )
- NCVT = 0
- IF( WNTVO .OR. WNTVAS ) THEN
- *
- * If right singular vectors desired, generate P'.
- * (Workspace: need 4*N-1, prefer 3*N+(N-1)*NB)
- *
- CALL SORGBR( 'P', N, N, N, A, LDA, WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- NCVT = N
- END IF
- IWORK = IE + N
- *
- * Perform bidiagonal QR iteration, computing right
- * singular vectors of A in A if desired
- * (Workspace: need BDSPAC)
- *
- CALL SBDSQR( 'U', N, NCVT, 0, 0, S, WORK( IE ), A, LDA,
- $ DUM, 1, DUM, 1, WORK( IWORK ), INFO )
- *
- * If right singular vectors desired in VT, copy them there
- *
- IF( WNTVAS )
- $ CALL SLACPY( 'F', N, N, A, LDA, VT, LDVT )
- *
- ELSE IF( WNTUO .AND. WNTVN ) THEN
- *
- * Path 2 (M much larger than N, JOBU='O', JOBVT='N')
- * N left singular vectors to be overwritten on A and
- * no right singular vectors to be computed
- *
- IF( LWORK.GE.N*N+MAX( 4*N, BDSPAC ) ) THEN
- *
- * Sufficient workspace for a fast algorithm
- *
- IR = 1
- IF( LWORK.GE.MAX( WRKBL, LDA*N+N )+LDA*N ) THEN
- *
- * WORK(IU) is LDA by N, WORK(IR) is LDA by N
- *
- LDWRKU = LDA
- LDWRKR = LDA
- ELSE IF( LWORK.GE.MAX( WRKBL, LDA*N+N )+N*N ) THEN
- *
- * WORK(IU) is LDA by N, WORK(IR) is N by N
- *
- LDWRKU = LDA
- LDWRKR = N
- ELSE
- *
- * WORK(IU) is LDWRKU by N, WORK(IR) is N by N
- *
- LDWRKU = ( LWORK-N*N-N ) / N
- LDWRKR = N
- END IF
- ITAU = IR + LDWRKR*N
- IWORK = ITAU + N
- *
- * Compute A=Q*R
- * (Workspace: need N*N+2*N, prefer N*N+N+N*NB)
- *
- CALL SGEQRF( M, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Copy R to WORK(IR) and zero out below it
- *
- CALL SLACPY( 'U', N, N, A, LDA, WORK( IR ), LDWRKR )
- CALL SLASET( 'L', N-1, N-1, ZERO, ZERO, WORK( IR+1 ),
- $ LDWRKR )
- *
- * Generate Q in A
- * (Workspace: need N*N+2*N, prefer N*N+N+N*NB)
- *
- CALL SORGQR( M, N, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IE = ITAU
- ITAUQ = IE + N
- ITAUP = ITAUQ + N
- IWORK = ITAUP + N
- *
- * Bidiagonalize R in WORK(IR)
- * (Workspace: need N*N+4*N, prefer N*N+3*N+2*N*NB)
- *
- CALL SGEBRD( N, N, WORK( IR ), LDWRKR, S, WORK( IE ),
- $ WORK( ITAUQ ), WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Generate left vectors bidiagonalizing R
- * (Workspace: need N*N+4*N, prefer N*N+3*N+N*NB)
- *
- CALL SORGBR( 'Q', N, N, N, WORK( IR ), LDWRKR,
- $ WORK( ITAUQ ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- IWORK = IE + N
- *
- * Perform bidiagonal QR iteration, computing left
- * singular vectors of R in WORK(IR)
- * (Workspace: need N*N+BDSPAC)
- *
- CALL SBDSQR( 'U', N, 0, N, 0, S, WORK( IE ), DUM, 1,
- $ WORK( IR ), LDWRKR, DUM, 1,
- $ WORK( IWORK ), INFO )
- IU = IE + N
- *
- * Multiply Q in A by left singular vectors of R in
- * WORK(IR), storing result in WORK(IU) and copying to A
- * (Workspace: need N*N+2*N, prefer N*N+M*N+N)
- *
- DO 10 I = 1, M, LDWRKU
- CHUNK = MIN( M-I+1, LDWRKU )
- CALL SGEMM( 'N', 'N', CHUNK, N, N, ONE, A( I, 1 ),
- $ LDA, WORK( IR ), LDWRKR, ZERO,
- $ WORK( IU ), LDWRKU )
- CALL SLACPY( 'F', CHUNK, N, WORK( IU ), LDWRKU,
- $ A( I, 1 ), LDA )
- 10 CONTINUE
- *
- ELSE
- *
- * Insufficient workspace for a fast algorithm
- *
- IE = 1
- ITAUQ = IE + N
- ITAUP = ITAUQ + N
- IWORK = ITAUP + N
- *
- * Bidiagonalize A
- * (Workspace: need 3*N+M, prefer 3*N+(M+N)*NB)
- *
- CALL SGEBRD( M, N, A, LDA, S, WORK( IE ),
- $ WORK( ITAUQ ), WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Generate left vectors bidiagonalizing A
- * (Workspace: need 4*N, prefer 3*N+N*NB)
- *
- CALL SORGBR( 'Q', M, N, N, A, LDA, WORK( ITAUQ ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IWORK = IE + N
- *
- * Perform bidiagonal QR iteration, computing left
- * singular vectors of A in A
- * (Workspace: need BDSPAC)
- *
- CALL SBDSQR( 'U', N, 0, M, 0, S, WORK( IE ), DUM, 1,
- $ A, LDA, DUM, 1, WORK( IWORK ), INFO )
- *
- END IF
- *
- ELSE IF( WNTUO .AND. WNTVAS ) THEN
- *
- * Path 3 (M much larger than N, JOBU='O', JOBVT='S' or 'A')
- * N left singular vectors to be overwritten on A and
- * N right singular vectors to be computed in VT
- *
- IF( LWORK.GE.N*N+MAX( 4*N, BDSPAC ) ) THEN
- *
- * Sufficient workspace for a fast algorithm
- *
- IR = 1
- IF( LWORK.GE.MAX( WRKBL, LDA*N+N )+LDA*N ) THEN
- *
- * WORK(IU) is LDA by N and WORK(IR) is LDA by N
- *
- LDWRKU = LDA
- LDWRKR = LDA
- ELSE IF( LWORK.GE.MAX( WRKBL, LDA*N+N )+N*N ) THEN
- *
- * WORK(IU) is LDA by N and WORK(IR) is N by N
- *
- LDWRKU = LDA
- LDWRKR = N
- ELSE
- *
- * WORK(IU) is LDWRKU by N and WORK(IR) is N by N
- *
- LDWRKU = ( LWORK-N*N-N ) / N
- LDWRKR = N
- END IF
- ITAU = IR + LDWRKR*N
- IWORK = ITAU + N
- *
- * Compute A=Q*R
- * (Workspace: need N*N+2*N, prefer N*N+N+N*NB)
- *
- CALL SGEQRF( M, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Copy R to VT, zeroing out below it
- *
- CALL SLACPY( 'U', N, N, A, LDA, VT, LDVT )
- IF( N.GT.1 )
- $ CALL SLASET( 'L', N-1, N-1, ZERO, ZERO,
- $ VT( 2, 1 ), LDVT )
- *
- * Generate Q in A
- * (Workspace: need N*N+2*N, prefer N*N+N+N*NB)
- *
- CALL SORGQR( M, N, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IE = ITAU
- ITAUQ = IE + N
- ITAUP = ITAUQ + N
- IWORK = ITAUP + N
- *
- * Bidiagonalize R in VT, copying result to WORK(IR)
- * (Workspace: need N*N+4*N, prefer N*N+3*N+2*N*NB)
- *
- CALL SGEBRD( N, N, VT, LDVT, S, WORK( IE ),
- $ WORK( ITAUQ ), WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- CALL SLACPY( 'L', N, N, VT, LDVT, WORK( IR ), LDWRKR )
- *
- * Generate left vectors bidiagonalizing R in WORK(IR)
- * (Workspace: need N*N+4*N, prefer N*N+3*N+N*NB)
- *
- CALL SORGBR( 'Q', N, N, N, WORK( IR ), LDWRKR,
- $ WORK( ITAUQ ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- *
- * Generate right vectors bidiagonalizing R in VT
- * (Workspace: need N*N+4*N-1, prefer N*N+3*N+(N-1)*NB)
- *
- CALL SORGBR( 'P', N, N, N, VT, LDVT, WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IWORK = IE + N
- *
- * Perform bidiagonal QR iteration, computing left
- * singular vectors of R in WORK(IR) and computing right
- * singular vectors of R in VT
- * (Workspace: need N*N+BDSPAC)
- *
- CALL SBDSQR( 'U', N, N, N, 0, S, WORK( IE ), VT, LDVT,
- $ WORK( IR ), LDWRKR, DUM, 1,
- $ WORK( IWORK ), INFO )
- IU = IE + N
- *
- * Multiply Q in A by left singular vectors of R in
- * WORK(IR), storing result in WORK(IU) and copying to A
- * (Workspace: need N*N+2*N, prefer N*N+M*N+N)
- *
- DO 20 I = 1, M, LDWRKU
- CHUNK = MIN( M-I+1, LDWRKU )
- CALL SGEMM( 'N', 'N', CHUNK, N, N, ONE, A( I, 1 ),
- $ LDA, WORK( IR ), LDWRKR, ZERO,
- $ WORK( IU ), LDWRKU )
- CALL SLACPY( 'F', CHUNK, N, WORK( IU ), LDWRKU,
- $ A( I, 1 ), LDA )
- 20 CONTINUE
- *
- ELSE
- *
- * Insufficient workspace for a fast algorithm
- *
- ITAU = 1
- IWORK = ITAU + N
- *
- * Compute A=Q*R
- * (Workspace: need 2*N, prefer N+N*NB)
- *
- CALL SGEQRF( M, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Copy R to VT, zeroing out below it
- *
- CALL SLACPY( 'U', N, N, A, LDA, VT, LDVT )
- IF( N.GT.1 )
- $ CALL SLASET( 'L', N-1, N-1, ZERO, ZERO,
- $ VT( 2, 1 ), LDVT )
- *
- * Generate Q in A
- * (Workspace: need 2*N, prefer N+N*NB)
- *
- CALL SORGQR( M, N, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IE = ITAU
- ITAUQ = IE + N
- ITAUP = ITAUQ + N
- IWORK = ITAUP + N
- *
- * Bidiagonalize R in VT
- * (Workspace: need 4*N, prefer 3*N+2*N*NB)
- *
- CALL SGEBRD( N, N, VT, LDVT, S, WORK( IE ),
- $ WORK( ITAUQ ), WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Multiply Q in A by left vectors bidiagonalizing R
- * (Workspace: need 3*N+M, prefer 3*N+M*NB)
- *
- CALL SORMBR( 'Q', 'R', 'N', M, N, N, VT, LDVT,
- $ WORK( ITAUQ ), A, LDA, WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- *
- * Generate right vectors bidiagonalizing R in VT
- * (Workspace: need 4*N-1, prefer 3*N+(N-1)*NB)
- *
- CALL SORGBR( 'P', N, N, N, VT, LDVT, WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IWORK = IE + N
- *
- * Perform bidiagonal QR iteration, computing left
- * singular vectors of A in A and computing right
- * singular vectors of A in VT
- * (Workspace: need BDSPAC)
- *
- CALL SBDSQR( 'U', N, N, M, 0, S, WORK( IE ), VT, LDVT,
- $ A, LDA, DUM, 1, WORK( IWORK ), INFO )
- *
- END IF
- *
- ELSE IF( WNTUS ) THEN
- *
- IF( WNTVN ) THEN
- *
- * Path 4 (M much larger than N, JOBU='S', JOBVT='N')
- * N left singular vectors to be computed in U and
- * no right singular vectors to be computed
- *
- IF( LWORK.GE.N*N+MAX( 4*N, BDSPAC ) ) THEN
- *
- * Sufficient workspace for a fast algorithm
- *
- IR = 1
- IF( LWORK.GE.WRKBL+LDA*N ) THEN
- *
- * WORK(IR) is LDA by N
- *
- LDWRKR = LDA
- ELSE
- *
- * WORK(IR) is N by N
- *
- LDWRKR = N
- END IF
- ITAU = IR + LDWRKR*N
- IWORK = ITAU + N
- *
- * Compute A=Q*R
- * (Workspace: need N*N+2*N, prefer N*N+N+N*NB)
- *
- CALL SGEQRF( M, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Copy R to WORK(IR), zeroing out below it
- *
- CALL SLACPY( 'U', N, N, A, LDA, WORK( IR ),
- $ LDWRKR )
- CALL SLASET( 'L', N-1, N-1, ZERO, ZERO,
- $ WORK( IR+1 ), LDWRKR )
- *
- * Generate Q in A
- * (Workspace: need N*N+2*N, prefer N*N+N+N*NB)
- *
- CALL SORGQR( M, N, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IE = ITAU
- ITAUQ = IE + N
- ITAUP = ITAUQ + N
- IWORK = ITAUP + N
- *
- * Bidiagonalize R in WORK(IR)
- * (Workspace: need N*N+4*N, prefer N*N+3*N+2*N*NB)
- *
- CALL SGEBRD( N, N, WORK( IR ), LDWRKR, S,
- $ WORK( IE ), WORK( ITAUQ ),
- $ WORK( ITAUP ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- *
- * Generate left vectors bidiagonalizing R in WORK(IR)
- * (Workspace: need N*N+4*N, prefer N*N+3*N+N*NB)
- *
- CALL SORGBR( 'Q', N, N, N, WORK( IR ), LDWRKR,
- $ WORK( ITAUQ ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- IWORK = IE + N
- *
- * Perform bidiagonal QR iteration, computing left
- * singular vectors of R in WORK(IR)
- * (Workspace: need N*N+BDSPAC)
- *
- CALL SBDSQR( 'U', N, 0, N, 0, S, WORK( IE ), DUM,
- $ 1, WORK( IR ), LDWRKR, DUM, 1,
- $ WORK( IWORK ), INFO )
- *
- * Multiply Q in A by left singular vectors of R in
- * WORK(IR), storing result in U
- * (Workspace: need N*N)
- *
- CALL SGEMM( 'N', 'N', M, N, N, ONE, A, LDA,
- $ WORK( IR ), LDWRKR, ZERO, U, LDU )
- *
- ELSE
- *
- * Insufficient workspace for a fast algorithm
- *
- ITAU = 1
- IWORK = ITAU + N
- *
- * Compute A=Q*R, copying result to U
- * (Workspace: need 2*N, prefer N+N*NB)
- *
- CALL SGEQRF( M, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- CALL SLACPY( 'L', M, N, A, LDA, U, LDU )
- *
- * Generate Q in U
- * (Workspace: need 2*N, prefer N+N*NB)
- *
- CALL SORGQR( M, N, N, U, LDU, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IE = ITAU
- ITAUQ = IE + N
- ITAUP = ITAUQ + N
- IWORK = ITAUP + N
- *
- * Zero out below R in A
- *
- IF( N .GT. 1 ) THEN
- CALL SLASET( 'L', N-1, N-1, ZERO, ZERO,
- $ A( 2, 1 ), LDA )
- END IF
- *
- * Bidiagonalize R in A
- * (Workspace: need 4*N, prefer 3*N+2*N*NB)
- *
- CALL SGEBRD( N, N, A, LDA, S, WORK( IE ),
- $ WORK( ITAUQ ), WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Multiply Q in U by left vectors bidiagonalizing R
- * (Workspace: need 3*N+M, prefer 3*N+M*NB)
- *
- CALL SORMBR( 'Q', 'R', 'N', M, N, N, A, LDA,
- $ WORK( ITAUQ ), U, LDU, WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- IWORK = IE + N
- *
- * Perform bidiagonal QR iteration, computing left
- * singular vectors of A in U
- * (Workspace: need BDSPAC)
- *
- CALL SBDSQR( 'U', N, 0, M, 0, S, WORK( IE ), DUM,
- $ 1, U, LDU, DUM, 1, WORK( IWORK ),
- $ INFO )
- *
- END IF
- *
- ELSE IF( WNTVO ) THEN
- *
- * Path 5 (M much larger than N, JOBU='S', JOBVT='O')
- * N left singular vectors to be computed in U and
- * N right singular vectors to be overwritten on A
- *
- IF( LWORK.GE.2*N*N+MAX( 4*N, BDSPAC ) ) THEN
- *
- * Sufficient workspace for a fast algorithm
- *
- IU = 1
- IF( LWORK.GE.WRKBL+2*LDA*N ) THEN
- *
- * WORK(IU) is LDA by N and WORK(IR) is LDA by N
- *
- LDWRKU = LDA
- IR = IU + LDWRKU*N
- LDWRKR = LDA
- ELSE IF( LWORK.GE.WRKBL+( LDA+N )*N ) THEN
- *
- * WORK(IU) is LDA by N and WORK(IR) is N by N
- *
- LDWRKU = LDA
- IR = IU + LDWRKU*N
- LDWRKR = N
- ELSE
- *
- * WORK(IU) is N by N and WORK(IR) is N by N
- *
- LDWRKU = N
- IR = IU + LDWRKU*N
- LDWRKR = N
- END IF
- ITAU = IR + LDWRKR*N
- IWORK = ITAU + N
- *
- * Compute A=Q*R
- * (Workspace: need 2*N*N+2*N, prefer 2*N*N+N+N*NB)
- *
- CALL SGEQRF( M, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Copy R to WORK(IU), zeroing out below it
- *
- CALL SLACPY( 'U', N, N, A, LDA, WORK( IU ),
- $ LDWRKU )
- CALL SLASET( 'L', N-1, N-1, ZERO, ZERO,
- $ WORK( IU+1 ), LDWRKU )
- *
- * Generate Q in A
- * (Workspace: need 2*N*N+2*N, prefer 2*N*N+N+N*NB)
- *
- CALL SORGQR( M, N, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IE = ITAU
- ITAUQ = IE + N
- ITAUP = ITAUQ + N
- IWORK = ITAUP + N
- *
- * Bidiagonalize R in WORK(IU), copying result to
- * WORK(IR)
- * (Workspace: need 2*N*N+4*N,
- * prefer 2*N*N+3*N+2*N*NB)
- *
- CALL SGEBRD( N, N, WORK( IU ), LDWRKU, S,
- $ WORK( IE ), WORK( ITAUQ ),
- $ WORK( ITAUP ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- CALL SLACPY( 'U', N, N, WORK( IU ), LDWRKU,
- $ WORK( IR ), LDWRKR )
- *
- * Generate left bidiagonalizing vectors in WORK(IU)
- * (Workspace: need 2*N*N+4*N, prefer 2*N*N+3*N+N*NB)
- *
- CALL SORGBR( 'Q', N, N, N, WORK( IU ), LDWRKU,
- $ WORK( ITAUQ ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- *
- * Generate right bidiagonalizing vectors in WORK(IR)
- * (Workspace: need 2*N*N+4*N-1,
- * prefer 2*N*N+3*N+(N-1)*NB)
- *
- CALL SORGBR( 'P', N, N, N, WORK( IR ), LDWRKR,
- $ WORK( ITAUP ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- IWORK = IE + N
- *
- * Perform bidiagonal QR iteration, computing left
- * singular vectors of R in WORK(IU) and computing
- * right singular vectors of R in WORK(IR)
- * (Workspace: need 2*N*N+BDSPAC)
- *
- CALL SBDSQR( 'U', N, N, N, 0, S, WORK( IE ),
- $ WORK( IR ), LDWRKR, WORK( IU ),
- $ LDWRKU, DUM, 1, WORK( IWORK ), INFO )
- *
- * Multiply Q in A by left singular vectors of R in
- * WORK(IU), storing result in U
- * (Workspace: need N*N)
- *
- CALL SGEMM( 'N', 'N', M, N, N, ONE, A, LDA,
- $ WORK( IU ), LDWRKU, ZERO, U, LDU )
- *
- * Copy right singular vectors of R to A
- * (Workspace: need N*N)
- *
- CALL SLACPY( 'F', N, N, WORK( IR ), LDWRKR, A,
- $ LDA )
- *
- ELSE
- *
- * Insufficient workspace for a fast algorithm
- *
- ITAU = 1
- IWORK = ITAU + N
- *
- * Compute A=Q*R, copying result to U
- * (Workspace: need 2*N, prefer N+N*NB)
- *
- CALL SGEQRF( M, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- CALL SLACPY( 'L', M, N, A, LDA, U, LDU )
- *
- * Generate Q in U
- * (Workspace: need 2*N, prefer N+N*NB)
- *
- CALL SORGQR( M, N, N, U, LDU, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IE = ITAU
- ITAUQ = IE + N
- ITAUP = ITAUQ + N
- IWORK = ITAUP + N
- *
- * Zero out below R in A
- *
- IF( N .GT. 1 ) THEN
- CALL SLASET( 'L', N-1, N-1, ZERO, ZERO,
- $ A( 2, 1 ), LDA )
- END IF
- *
- * Bidiagonalize R in A
- * (Workspace: need 4*N, prefer 3*N+2*N*NB)
- *
- CALL SGEBRD( N, N, A, LDA, S, WORK( IE ),
- $ WORK( ITAUQ ), WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Multiply Q in U by left vectors bidiagonalizing R
- * (Workspace: need 3*N+M, prefer 3*N+M*NB)
- *
- CALL SORMBR( 'Q', 'R', 'N', M, N, N, A, LDA,
- $ WORK( ITAUQ ), U, LDU, WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- *
- * Generate right vectors bidiagonalizing R in A
- * (Workspace: need 4*N-1, prefer 3*N+(N-1)*NB)
- *
- CALL SORGBR( 'P', N, N, N, A, LDA, WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IWORK = IE + N
- *
- * Perform bidiagonal QR iteration, computing left
- * singular vectors of A in U and computing right
- * singular vectors of A in A
- * (Workspace: need BDSPAC)
- *
- CALL SBDSQR( 'U', N, N, M, 0, S, WORK( IE ), A,
- $ LDA, U, LDU, DUM, 1, WORK( IWORK ),
- $ INFO )
- *
- END IF
- *
- ELSE IF( WNTVAS ) THEN
- *
- * Path 6 (M much larger than N, JOBU='S', JOBVT='S'
- * or 'A')
- * N left singular vectors to be computed in U and
- * N right singular vectors to be computed in VT
- *
- IF( LWORK.GE.N*N+MAX( 4*N, BDSPAC ) ) THEN
- *
- * Sufficient workspace for a fast algorithm
- *
- IU = 1
- IF( LWORK.GE.WRKBL+LDA*N ) THEN
- *
- * WORK(IU) is LDA by N
- *
- LDWRKU = LDA
- ELSE
- *
- * WORK(IU) is N by N
- *
- LDWRKU = N
- END IF
- ITAU = IU + LDWRKU*N
- IWORK = ITAU + N
- *
- * Compute A=Q*R
- * (Workspace: need N*N+2*N, prefer N*N+N+N*NB)
- *
- CALL SGEQRF( M, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Copy R to WORK(IU), zeroing out below it
- *
- CALL SLACPY( 'U', N, N, A, LDA, WORK( IU ),
- $ LDWRKU )
- CALL SLASET( 'L', N-1, N-1, ZERO, ZERO,
- $ WORK( IU+1 ), LDWRKU )
- *
- * Generate Q in A
- * (Workspace: need N*N+2*N, prefer N*N+N+N*NB)
- *
- CALL SORGQR( M, N, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IE = ITAU
- ITAUQ = IE + N
- ITAUP = ITAUQ + N
- IWORK = ITAUP + N
- *
- * Bidiagonalize R in WORK(IU), copying result to VT
- * (Workspace: need N*N+4*N, prefer N*N+3*N+2*N*NB)
- *
- CALL SGEBRD( N, N, WORK( IU ), LDWRKU, S,
- $ WORK( IE ), WORK( ITAUQ ),
- $ WORK( ITAUP ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- CALL SLACPY( 'U', N, N, WORK( IU ), LDWRKU, VT,
- $ LDVT )
- *
- * Generate left bidiagonalizing vectors in WORK(IU)
- * (Workspace: need N*N+4*N, prefer N*N+3*N+N*NB)
- *
- CALL SORGBR( 'Q', N, N, N, WORK( IU ), LDWRKU,
- $ WORK( ITAUQ ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- *
- * Generate right bidiagonalizing vectors in VT
- * (Workspace: need N*N+4*N-1,
- * prefer N*N+3*N+(N-1)*NB)
- *
- CALL SORGBR( 'P', N, N, N, VT, LDVT, WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IWORK = IE + N
- *
- * Perform bidiagonal QR iteration, computing left
- * singular vectors of R in WORK(IU) and computing
- * right singular vectors of R in VT
- * (Workspace: need N*N+BDSPAC)
- *
- CALL SBDSQR( 'U', N, N, N, 0, S, WORK( IE ), VT,
- $ LDVT, WORK( IU ), LDWRKU, DUM, 1,
- $ WORK( IWORK ), INFO )
- *
- * Multiply Q in A by left singular vectors of R in
- * WORK(IU), storing result in U
- * (Workspace: need N*N)
- *
- CALL SGEMM( 'N', 'N', M, N, N, ONE, A, LDA,
- $ WORK( IU ), LDWRKU, ZERO, U, LDU )
- *
- ELSE
- *
- * Insufficient workspace for a fast algorithm
- *
- ITAU = 1
- IWORK = ITAU + N
- *
- * Compute A=Q*R, copying result to U
- * (Workspace: need 2*N, prefer N+N*NB)
- *
- CALL SGEQRF( M, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- CALL SLACPY( 'L', M, N, A, LDA, U, LDU )
- *
- * Generate Q in U
- * (Workspace: need 2*N, prefer N+N*NB)
- *
- CALL SORGQR( M, N, N, U, LDU, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Copy R to VT, zeroing out below it
- *
- CALL SLACPY( 'U', N, N, A, LDA, VT, LDVT )
- IF( N.GT.1 )
- $ CALL SLASET( 'L', N-1, N-1, ZERO, ZERO,
- $ VT( 2, 1 ), LDVT )
- IE = ITAU
- ITAUQ = IE + N
- ITAUP = ITAUQ + N
- IWORK = ITAUP + N
- *
- * Bidiagonalize R in VT
- * (Workspace: need 4*N, prefer 3*N+2*N*NB)
- *
- CALL SGEBRD( N, N, VT, LDVT, S, WORK( IE ),
- $ WORK( ITAUQ ), WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Multiply Q in U by left bidiagonalizing vectors
- * in VT
- * (Workspace: need 3*N+M, prefer 3*N+M*NB)
- *
- CALL SORMBR( 'Q', 'R', 'N', M, N, N, VT, LDVT,
- $ WORK( ITAUQ ), U, LDU, WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- *
- * Generate right bidiagonalizing vectors in VT
- * (Workspace: need 4*N-1, prefer 3*N+(N-1)*NB)
- *
- CALL SORGBR( 'P', N, N, N, VT, LDVT, WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IWORK = IE + N
- *
- * Perform bidiagonal QR iteration, computing left
- * singular vectors of A in U and computing right
- * singular vectors of A in VT
- * (Workspace: need BDSPAC)
- *
- CALL SBDSQR( 'U', N, N, M, 0, S, WORK( IE ), VT,
- $ LDVT, U, LDU, DUM, 1, WORK( IWORK ),
- $ INFO )
- *
- END IF
- *
- END IF
- *
- ELSE IF( WNTUA ) THEN
- *
- IF( WNTVN ) THEN
- *
- * Path 7 (M much larger than N, JOBU='A', JOBVT='N')
- * M left singular vectors to be computed in U and
- * no right singular vectors to be computed
- *
- IF( LWORK.GE.N*N+MAX( N+M, 4*N, BDSPAC ) ) THEN
- *
- * Sufficient workspace for a fast algorithm
- *
- IR = 1
- IF( LWORK.GE.WRKBL+LDA*N ) THEN
- *
- * WORK(IR) is LDA by N
- *
- LDWRKR = LDA
- ELSE
- *
- * WORK(IR) is N by N
- *
- LDWRKR = N
- END IF
- ITAU = IR + LDWRKR*N
- IWORK = ITAU + N
- *
- * Compute A=Q*R, copying result to U
- * (Workspace: need N*N+2*N, prefer N*N+N+N*NB)
- *
- CALL SGEQRF( M, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- CALL SLACPY( 'L', M, N, A, LDA, U, LDU )
- *
- * Copy R to WORK(IR), zeroing out below it
- *
- CALL SLACPY( 'U', N, N, A, LDA, WORK( IR ),
- $ LDWRKR )
- CALL SLASET( 'L', N-1, N-1, ZERO, ZERO,
- $ WORK( IR+1 ), LDWRKR )
- *
- * Generate Q in U
- * (Workspace: need N*N+N+M, prefer N*N+N+M*NB)
- *
- CALL SORGQR( M, M, N, U, LDU, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IE = ITAU
- ITAUQ = IE + N
- ITAUP = ITAUQ + N
- IWORK = ITAUP + N
- *
- * Bidiagonalize R in WORK(IR)
- * (Workspace: need N*N+4*N, prefer N*N+3*N+2*N*NB)
- *
- CALL SGEBRD( N, N, WORK( IR ), LDWRKR, S,
- $ WORK( IE ), WORK( ITAUQ ),
- $ WORK( ITAUP ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- *
- * Generate left bidiagonalizing vectors in WORK(IR)
- * (Workspace: need N*N+4*N, prefer N*N+3*N+N*NB)
- *
- CALL SORGBR( 'Q', N, N, N, WORK( IR ), LDWRKR,
- $ WORK( ITAUQ ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- IWORK = IE + N
- *
- * Perform bidiagonal QR iteration, computing left
- * singular vectors of R in WORK(IR)
- * (Workspace: need N*N+BDSPAC)
- *
- CALL SBDSQR( 'U', N, 0, N, 0, S, WORK( IE ), DUM,
- $ 1, WORK( IR ), LDWRKR, DUM, 1,
- $ WORK( IWORK ), INFO )
- *
- * Multiply Q in U by left singular vectors of R in
- * WORK(IR), storing result in A
- * (Workspace: need N*N)
- *
- CALL SGEMM( 'N', 'N', M, N, N, ONE, U, LDU,
- $ WORK( IR ), LDWRKR, ZERO, A, LDA )
- *
- * Copy left singular vectors of A from A to U
- *
- CALL SLACPY( 'F', M, N, A, LDA, U, LDU )
- *
- ELSE
- *
- * Insufficient workspace for a fast algorithm
- *
- ITAU = 1
- IWORK = ITAU + N
- *
- * Compute A=Q*R, copying result to U
- * (Workspace: need 2*N, prefer N+N*NB)
- *
- CALL SGEQRF( M, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- CALL SLACPY( 'L', M, N, A, LDA, U, LDU )
- *
- * Generate Q in U
- * (Workspace: need N+M, prefer N+M*NB)
- *
- CALL SORGQR( M, M, N, U, LDU, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IE = ITAU
- ITAUQ = IE + N
- ITAUP = ITAUQ + N
- IWORK = ITAUP + N
- *
- * Zero out below R in A
- *
- IF( N .GT. 1 ) THEN
- CALL SLASET( 'L', N-1, N-1, ZERO, ZERO,
- $ A( 2, 1 ), LDA )
- END IF
- *
- * Bidiagonalize R in A
- * (Workspace: need 4*N, prefer 3*N+2*N*NB)
- *
- CALL SGEBRD( N, N, A, LDA, S, WORK( IE ),
- $ WORK( ITAUQ ), WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Multiply Q in U by left bidiagonalizing vectors
- * in A
- * (Workspace: need 3*N+M, prefer 3*N+M*NB)
- *
- CALL SORMBR( 'Q', 'R', 'N', M, N, N, A, LDA,
- $ WORK( ITAUQ ), U, LDU, WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- IWORK = IE + N
- *
- * Perform bidiagonal QR iteration, computing left
- * singular vectors of A in U
- * (Workspace: need BDSPAC)
- *
- CALL SBDSQR( 'U', N, 0, M, 0, S, WORK( IE ), DUM,
- $ 1, U, LDU, DUM, 1, WORK( IWORK ),
- $ INFO )
- *
- END IF
- *
- ELSE IF( WNTVO ) THEN
- *
- * Path 8 (M much larger than N, JOBU='A', JOBVT='O')
- * M left singular vectors to be computed in U and
- * N right singular vectors to be overwritten on A
- *
- IF( LWORK.GE.2*N*N+MAX( N+M, 4*N, BDSPAC ) ) THEN
- *
- * Sufficient workspace for a fast algorithm
- *
- IU = 1
- IF( LWORK.GE.WRKBL+2*LDA*N ) THEN
- *
- * WORK(IU) is LDA by N and WORK(IR) is LDA by N
- *
- LDWRKU = LDA
- IR = IU + LDWRKU*N
- LDWRKR = LDA
- ELSE IF( LWORK.GE.WRKBL+( LDA+N )*N ) THEN
- *
- * WORK(IU) is LDA by N and WORK(IR) is N by N
- *
- LDWRKU = LDA
- IR = IU + LDWRKU*N
- LDWRKR = N
- ELSE
- *
- * WORK(IU) is N by N and WORK(IR) is N by N
- *
- LDWRKU = N
- IR = IU + LDWRKU*N
- LDWRKR = N
- END IF
- ITAU = IR + LDWRKR*N
- IWORK = ITAU + N
- *
- * Compute A=Q*R, copying result to U
- * (Workspace: need 2*N*N+2*N, prefer 2*N*N+N+N*NB)
- *
- CALL SGEQRF( M, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- CALL SLACPY( 'L', M, N, A, LDA, U, LDU )
- *
- * Generate Q in U
- * (Workspace: need 2*N*N+N+M, prefer 2*N*N+N+M*NB)
- *
- CALL SORGQR( M, M, N, U, LDU, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Copy R to WORK(IU), zeroing out below it
- *
- CALL SLACPY( 'U', N, N, A, LDA, WORK( IU ),
- $ LDWRKU )
- CALL SLASET( 'L', N-1, N-1, ZERO, ZERO,
- $ WORK( IU+1 ), LDWRKU )
- IE = ITAU
- ITAUQ = IE + N
- ITAUP = ITAUQ + N
- IWORK = ITAUP + N
- *
- * Bidiagonalize R in WORK(IU), copying result to
- * WORK(IR)
- * (Workspace: need 2*N*N+4*N,
- * prefer 2*N*N+3*N+2*N*NB)
- *
- CALL SGEBRD( N, N, WORK( IU ), LDWRKU, S,
- $ WORK( IE ), WORK( ITAUQ ),
- $ WORK( ITAUP ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- CALL SLACPY( 'U', N, N, WORK( IU ), LDWRKU,
- $ WORK( IR ), LDWRKR )
- *
- * Generate left bidiagonalizing vectors in WORK(IU)
- * (Workspace: need 2*N*N+4*N, prefer 2*N*N+3*N+N*NB)
- *
- CALL SORGBR( 'Q', N, N, N, WORK( IU ), LDWRKU,
- $ WORK( ITAUQ ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- *
- * Generate right bidiagonalizing vectors in WORK(IR)
- * (Workspace: need 2*N*N+4*N-1,
- * prefer 2*N*N+3*N+(N-1)*NB)
- *
- CALL SORGBR( 'P', N, N, N, WORK( IR ), LDWRKR,
- $ WORK( ITAUP ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- IWORK = IE + N
- *
- * Perform bidiagonal QR iteration, computing left
- * singular vectors of R in WORK(IU) and computing
- * right singular vectors of R in WORK(IR)
- * (Workspace: need 2*N*N+BDSPAC)
- *
- CALL SBDSQR( 'U', N, N, N, 0, S, WORK( IE ),
- $ WORK( IR ), LDWRKR, WORK( IU ),
- $ LDWRKU, DUM, 1, WORK( IWORK ), INFO )
- *
- * Multiply Q in U by left singular vectors of R in
- * WORK(IU), storing result in A
- * (Workspace: need N*N)
- *
- CALL SGEMM( 'N', 'N', M, N, N, ONE, U, LDU,
- $ WORK( IU ), LDWRKU, ZERO, A, LDA )
- *
- * Copy left singular vectors of A from A to U
- *
- CALL SLACPY( 'F', M, N, A, LDA, U, LDU )
- *
- * Copy right singular vectors of R from WORK(IR) to A
- *
- CALL SLACPY( 'F', N, N, WORK( IR ), LDWRKR, A,
- $ LDA )
- *
- ELSE
- *
- * Insufficient workspace for a fast algorithm
- *
- ITAU = 1
- IWORK = ITAU + N
- *
- * Compute A=Q*R, copying result to U
- * (Workspace: need 2*N, prefer N+N*NB)
- *
- CALL SGEQRF( M, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- CALL SLACPY( 'L', M, N, A, LDA, U, LDU )
- *
- * Generate Q in U
- * (Workspace: need N+M, prefer N+M*NB)
- *
- CALL SORGQR( M, M, N, U, LDU, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IE = ITAU
- ITAUQ = IE + N
- ITAUP = ITAUQ + N
- IWORK = ITAUP + N
- *
- * Zero out below R in A
- *
- IF( N .GT. 1 ) THEN
- CALL SLASET( 'L', N-1, N-1, ZERO, ZERO,
- $ A( 2, 1 ), LDA )
- END IF
- *
- * Bidiagonalize R in A
- * (Workspace: need 4*N, prefer 3*N+2*N*NB)
- *
- CALL SGEBRD( N, N, A, LDA, S, WORK( IE ),
- $ WORK( ITAUQ ), WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Multiply Q in U by left bidiagonalizing vectors
- * in A
- * (Workspace: need 3*N+M, prefer 3*N+M*NB)
- *
- CALL SORMBR( 'Q', 'R', 'N', M, N, N, A, LDA,
- $ WORK( ITAUQ ), U, LDU, WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- *
- * Generate right bidiagonalizing vectors in A
- * (Workspace: need 4*N-1, prefer 3*N+(N-1)*NB)
- *
- CALL SORGBR( 'P', N, N, N, A, LDA, WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IWORK = IE + N
- *
- * Perform bidiagonal QR iteration, computing left
- * singular vectors of A in U and computing right
- * singular vectors of A in A
- * (Workspace: need BDSPAC)
- *
- CALL SBDSQR( 'U', N, N, M, 0, S, WORK( IE ), A,
- $ LDA, U, LDU, DUM, 1, WORK( IWORK ),
- $ INFO )
- *
- END IF
- *
- ELSE IF( WNTVAS ) THEN
- *
- * Path 9 (M much larger than N, JOBU='A', JOBVT='S'
- * or 'A')
- * M left singular vectors to be computed in U and
- * N right singular vectors to be computed in VT
- *
- IF( LWORK.GE.N*N+MAX( N+M, 4*N, BDSPAC ) ) THEN
- *
- * Sufficient workspace for a fast algorithm
- *
- IU = 1
- IF( LWORK.GE.WRKBL+LDA*N ) THEN
- *
- * WORK(IU) is LDA by N
- *
- LDWRKU = LDA
- ELSE
- *
- * WORK(IU) is N by N
- *
- LDWRKU = N
- END IF
- ITAU = IU + LDWRKU*N
- IWORK = ITAU + N
- *
- * Compute A=Q*R, copying result to U
- * (Workspace: need N*N+2*N, prefer N*N+N+N*NB)
- *
- CALL SGEQRF( M, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- CALL SLACPY( 'L', M, N, A, LDA, U, LDU )
- *
- * Generate Q in U
- * (Workspace: need N*N+N+M, prefer N*N+N+M*NB)
- *
- CALL SORGQR( M, M, N, U, LDU, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Copy R to WORK(IU), zeroing out below it
- *
- CALL SLACPY( 'U', N, N, A, LDA, WORK( IU ),
- $ LDWRKU )
- CALL SLASET( 'L', N-1, N-1, ZERO, ZERO,
- $ WORK( IU+1 ), LDWRKU )
- IE = ITAU
- ITAUQ = IE + N
- ITAUP = ITAUQ + N
- IWORK = ITAUP + N
- *
- * Bidiagonalize R in WORK(IU), copying result to VT
- * (Workspace: need N*N+4*N, prefer N*N+3*N+2*N*NB)
- *
- CALL SGEBRD( N, N, WORK( IU ), LDWRKU, S,
- $ WORK( IE ), WORK( ITAUQ ),
- $ WORK( ITAUP ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- CALL SLACPY( 'U', N, N, WORK( IU ), LDWRKU, VT,
- $ LDVT )
- *
- * Generate left bidiagonalizing vectors in WORK(IU)
- * (Workspace: need N*N+4*N, prefer N*N+3*N+N*NB)
- *
- CALL SORGBR( 'Q', N, N, N, WORK( IU ), LDWRKU,
- $ WORK( ITAUQ ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- *
- * Generate right bidiagonalizing vectors in VT
- * (Workspace: need N*N+4*N-1,
- * prefer N*N+3*N+(N-1)*NB)
- *
- CALL SORGBR( 'P', N, N, N, VT, LDVT, WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IWORK = IE + N
- *
- * Perform bidiagonal QR iteration, computing left
- * singular vectors of R in WORK(IU) and computing
- * right singular vectors of R in VT
- * (Workspace: need N*N+BDSPAC)
- *
- CALL SBDSQR( 'U', N, N, N, 0, S, WORK( IE ), VT,
- $ LDVT, WORK( IU ), LDWRKU, DUM, 1,
- $ WORK( IWORK ), INFO )
- *
- * Multiply Q in U by left singular vectors of R in
- * WORK(IU), storing result in A
- * (Workspace: need N*N)
- *
- CALL SGEMM( 'N', 'N', M, N, N, ONE, U, LDU,
- $ WORK( IU ), LDWRKU, ZERO, A, LDA )
- *
- * Copy left singular vectors of A from A to U
- *
- CALL SLACPY( 'F', M, N, A, LDA, U, LDU )
- *
- ELSE
- *
- * Insufficient workspace for a fast algorithm
- *
- ITAU = 1
- IWORK = ITAU + N
- *
- * Compute A=Q*R, copying result to U
- * (Workspace: need 2*N, prefer N+N*NB)
- *
- CALL SGEQRF( M, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- CALL SLACPY( 'L', M, N, A, LDA, U, LDU )
- *
- * Generate Q in U
- * (Workspace: need N+M, prefer N+M*NB)
- *
- CALL SORGQR( M, M, N, U, LDU, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Copy R from A to VT, zeroing out below it
- *
- CALL SLACPY( 'U', N, N, A, LDA, VT, LDVT )
- IF( N.GT.1 )
- $ CALL SLASET( 'L', N-1, N-1, ZERO, ZERO,
- $ VT( 2, 1 ), LDVT )
- IE = ITAU
- ITAUQ = IE + N
- ITAUP = ITAUQ + N
- IWORK = ITAUP + N
- *
- * Bidiagonalize R in VT
- * (Workspace: need 4*N, prefer 3*N+2*N*NB)
- *
- CALL SGEBRD( N, N, VT, LDVT, S, WORK( IE ),
- $ WORK( ITAUQ ), WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Multiply Q in U by left bidiagonalizing vectors
- * in VT
- * (Workspace: need 3*N+M, prefer 3*N+M*NB)
- *
- CALL SORMBR( 'Q', 'R', 'N', M, N, N, VT, LDVT,
- $ WORK( ITAUQ ), U, LDU, WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- *
- * Generate right bidiagonalizing vectors in VT
- * (Workspace: need 4*N-1, prefer 3*N+(N-1)*NB)
- *
- CALL SORGBR( 'P', N, N, N, VT, LDVT, WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IWORK = IE + N
- *
- * Perform bidiagonal QR iteration, computing left
- * singular vectors of A in U and computing right
- * singular vectors of A in VT
- * (Workspace: need BDSPAC)
- *
- CALL SBDSQR( 'U', N, N, M, 0, S, WORK( IE ), VT,
- $ LDVT, U, LDU, DUM, 1, WORK( IWORK ),
- $ INFO )
- *
- END IF
- *
- END IF
- *
- END IF
- *
- ELSE
- *
- * M .LT. MNTHR
- *
- * Path 10 (M at least N, but not much larger)
- * Reduce to bidiagonal form without QR decomposition
- *
- IE = 1
- ITAUQ = IE + N
- ITAUP = ITAUQ + N
- IWORK = ITAUP + N
- *
- * Bidiagonalize A
- * (Workspace: need 3*N+M, prefer 3*N+(M+N)*NB)
- *
- CALL SGEBRD( M, N, A, LDA, S, WORK( IE ), WORK( ITAUQ ),
- $ WORK( ITAUP ), WORK( IWORK ), LWORK-IWORK+1,
- $ IERR )
- IF( WNTUAS ) THEN
- *
- * If left singular vectors desired in U, copy result to U
- * and generate left bidiagonalizing vectors in U
- * (Workspace: need 3*N+NCU, prefer 3*N+NCU*NB)
- *
- CALL SLACPY( 'L', M, N, A, LDA, U, LDU )
- IF( WNTUS )
- $ NCU = N
- IF( WNTUA )
- $ NCU = M
- CALL SORGBR( 'Q', M, NCU, N, U, LDU, WORK( ITAUQ ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- END IF
- IF( WNTVAS ) THEN
- *
- * If right singular vectors desired in VT, copy result to
- * VT and generate right bidiagonalizing vectors in VT
- * (Workspace: need 4*N-1, prefer 3*N+(N-1)*NB)
- *
- CALL SLACPY( 'U', N, N, A, LDA, VT, LDVT )
- CALL SORGBR( 'P', N, N, N, VT, LDVT, WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- END IF
- IF( WNTUO ) THEN
- *
- * If left singular vectors desired in A, generate left
- * bidiagonalizing vectors in A
- * (Workspace: need 4*N, prefer 3*N+N*NB)
- *
- CALL SORGBR( 'Q', M, N, N, A, LDA, WORK( ITAUQ ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- END IF
- IF( WNTVO ) THEN
- *
- * If right singular vectors desired in A, generate right
- * bidiagonalizing vectors in A
- * (Workspace: need 4*N-1, prefer 3*N+(N-1)*NB)
- *
- CALL SORGBR( 'P', N, N, N, A, LDA, WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- END IF
- IWORK = IE + N
- IF( WNTUAS .OR. WNTUO )
- $ NRU = M
- IF( WNTUN )
- $ NRU = 0
- IF( WNTVAS .OR. WNTVO )
- $ NCVT = N
- IF( WNTVN )
- $ NCVT = 0
- IF( ( .NOT.WNTUO ) .AND. ( .NOT.WNTVO ) ) THEN
- *
- * Perform bidiagonal QR iteration, if desired, computing
- * left singular vectors in U and computing right singular
- * vectors in VT
- * (Workspace: need BDSPAC)
- *
- CALL SBDSQR( 'U', N, NCVT, NRU, 0, S, WORK( IE ), VT,
- $ LDVT, U, LDU, DUM, 1, WORK( IWORK ), INFO )
- ELSE IF( ( .NOT.WNTUO ) .AND. WNTVO ) THEN
- *
- * Perform bidiagonal QR iteration, if desired, computing
- * left singular vectors in U and computing right singular
- * vectors in A
- * (Workspace: need BDSPAC)
- *
- CALL SBDSQR( 'U', N, NCVT, NRU, 0, S, WORK( IE ), A, LDA,
- $ U, LDU, DUM, 1, WORK( IWORK ), INFO )
- ELSE
- *
- * Perform bidiagonal QR iteration, if desired, computing
- * left singular vectors in A and computing right singular
- * vectors in VT
- * (Workspace: need BDSPAC)
- *
- CALL SBDSQR( 'U', N, NCVT, NRU, 0, S, WORK( IE ), VT,
- $ LDVT, A, LDA, DUM, 1, WORK( IWORK ), INFO )
- END IF
- *
- END IF
- *
- ELSE
- *
- * A has more columns than rows. If A has sufficiently more
- * columns than rows, first reduce using the LQ decomposition (if
- * sufficient workspace available)
- *
- IF( N.GE.MNTHR ) THEN
- *
- IF( WNTVN ) THEN
- *
- * Path 1t(N much larger than M, JOBVT='N')
- * No right singular vectors to be computed
- *
- ITAU = 1
- IWORK = ITAU + M
- *
- * Compute A=L*Q
- * (Workspace: need 2*M, prefer M+M*NB)
- *
- CALL SGELQF( M, N, A, LDA, WORK( ITAU ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- *
- * Zero out above L
- *
- CALL SLASET( 'U', M-1, M-1, ZERO, ZERO, A( 1, 2 ), LDA )
- IE = 1
- ITAUQ = IE + M
- ITAUP = ITAUQ + M
- IWORK = ITAUP + M
- *
- * Bidiagonalize L in A
- * (Workspace: need 4*M, prefer 3*M+2*M*NB)
- *
- CALL SGEBRD( M, M, A, LDA, S, WORK( IE ), WORK( ITAUQ ),
- $ WORK( ITAUP ), WORK( IWORK ), LWORK-IWORK+1,
- $ IERR )
- IF( WNTUO .OR. WNTUAS ) THEN
- *
- * If left singular vectors desired, generate Q
- * (Workspace: need 4*M, prefer 3*M+M*NB)
- *
- CALL SORGBR( 'Q', M, M, M, A, LDA, WORK( ITAUQ ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- END IF
- IWORK = IE + M
- NRU = 0
- IF( WNTUO .OR. WNTUAS )
- $ NRU = M
- *
- * Perform bidiagonal QR iteration, computing left singular
- * vectors of A in A if desired
- * (Workspace: need BDSPAC)
- *
- CALL SBDSQR( 'U', M, 0, NRU, 0, S, WORK( IE ), DUM, 1, A,
- $ LDA, DUM, 1, WORK( IWORK ), INFO )
- *
- * If left singular vectors desired in U, copy them there
- *
- IF( WNTUAS )
- $ CALL SLACPY( 'F', M, M, A, LDA, U, LDU )
- *
- ELSE IF( WNTVO .AND. WNTUN ) THEN
- *
- * Path 2t(N much larger than M, JOBU='N', JOBVT='O')
- * M right singular vectors to be overwritten on A and
- * no left singular vectors to be computed
- *
- IF( LWORK.GE.M*M+MAX( 4*M, BDSPAC ) ) THEN
- *
- * Sufficient workspace for a fast algorithm
- *
- IR = 1
- IF( LWORK.GE.MAX( WRKBL, LDA*N+M )+LDA*M ) THEN
- *
- * WORK(IU) is LDA by N and WORK(IR) is LDA by M
- *
- LDWRKU = LDA
- CHUNK = N
- LDWRKR = LDA
- ELSE IF( LWORK.GE.MAX( WRKBL, LDA*N+M )+M*M ) THEN
- *
- * WORK(IU) is LDA by N and WORK(IR) is M by M
- *
- LDWRKU = LDA
- CHUNK = N
- LDWRKR = M
- ELSE
- *
- * WORK(IU) is M by CHUNK and WORK(IR) is M by M
- *
- LDWRKU = M
- CHUNK = ( LWORK-M*M-M ) / M
- LDWRKR = M
- END IF
- ITAU = IR + LDWRKR*M
- IWORK = ITAU + M
- *
- * Compute A=L*Q
- * (Workspace: need M*M+2*M, prefer M*M+M+M*NB)
- *
- CALL SGELQF( M, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Copy L to WORK(IR) and zero out above it
- *
- CALL SLACPY( 'L', M, M, A, LDA, WORK( IR ), LDWRKR )
- CALL SLASET( 'U', M-1, M-1, ZERO, ZERO,
- $ WORK( IR+LDWRKR ), LDWRKR )
- *
- * Generate Q in A
- * (Workspace: need M*M+2*M, prefer M*M+M+M*NB)
- *
- CALL SORGLQ( M, N, M, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IE = ITAU
- ITAUQ = IE + M
- ITAUP = ITAUQ + M
- IWORK = ITAUP + M
- *
- * Bidiagonalize L in WORK(IR)
- * (Workspace: need M*M+4*M, prefer M*M+3*M+2*M*NB)
- *
- CALL SGEBRD( M, M, WORK( IR ), LDWRKR, S, WORK( IE ),
- $ WORK( ITAUQ ), WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Generate right vectors bidiagonalizing L
- * (Workspace: need M*M+4*M-1, prefer M*M+3*M+(M-1)*NB)
- *
- CALL SORGBR( 'P', M, M, M, WORK( IR ), LDWRKR,
- $ WORK( ITAUP ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- IWORK = IE + M
- *
- * Perform bidiagonal QR iteration, computing right
- * singular vectors of L in WORK(IR)
- * (Workspace: need M*M+BDSPAC)
- *
- CALL SBDSQR( 'U', M, M, 0, 0, S, WORK( IE ),
- $ WORK( IR ), LDWRKR, DUM, 1, DUM, 1,
- $ WORK( IWORK ), INFO )
- IU = IE + M
- *
- * Multiply right singular vectors of L in WORK(IR) by Q
- * in A, storing result in WORK(IU) and copying to A
- * (Workspace: need M*M+2*M, prefer M*M+M*N+M)
- *
- DO 30 I = 1, N, CHUNK
- BLK = MIN( N-I+1, CHUNK )
- CALL SGEMM( 'N', 'N', M, BLK, M, ONE, WORK( IR ),
- $ LDWRKR, A( 1, I ), LDA, ZERO,
- $ WORK( IU ), LDWRKU )
- CALL SLACPY( 'F', M, BLK, WORK( IU ), LDWRKU,
- $ A( 1, I ), LDA )
- 30 CONTINUE
- *
- ELSE
- *
- * Insufficient workspace for a fast algorithm
- *
- IE = 1
- ITAUQ = IE + M
- ITAUP = ITAUQ + M
- IWORK = ITAUP + M
- *
- * Bidiagonalize A
- * (Workspace: need 3*M+N, prefer 3*M+(M+N)*NB)
- *
- CALL SGEBRD( M, N, A, LDA, S, WORK( IE ),
- $ WORK( ITAUQ ), WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Generate right vectors bidiagonalizing A
- * (Workspace: need 4*M, prefer 3*M+M*NB)
- *
- CALL SORGBR( 'P', M, N, M, A, LDA, WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IWORK = IE + M
- *
- * Perform bidiagonal QR iteration, computing right
- * singular vectors of A in A
- * (Workspace: need BDSPAC)
- *
- CALL SBDSQR( 'L', M, N, 0, 0, S, WORK( IE ), A, LDA,
- $ DUM, 1, DUM, 1, WORK( IWORK ), INFO )
- *
- END IF
- *
- ELSE IF( WNTVO .AND. WNTUAS ) THEN
- *
- * Path 3t(N much larger than M, JOBU='S' or 'A', JOBVT='O')
- * M right singular vectors to be overwritten on A and
- * M left singular vectors to be computed in U
- *
- IF( LWORK.GE.M*M+MAX( 4*M, BDSPAC ) ) THEN
- *
- * Sufficient workspace for a fast algorithm
- *
- IR = 1
- IF( LWORK.GE.MAX( WRKBL, LDA*N+M )+LDA*M ) THEN
- *
- * WORK(IU) is LDA by N and WORK(IR) is LDA by M
- *
- LDWRKU = LDA
- CHUNK = N
- LDWRKR = LDA
- ELSE IF( LWORK.GE.MAX( WRKBL, LDA*N+M )+M*M ) THEN
- *
- * WORK(IU) is LDA by N and WORK(IR) is M by M
- *
- LDWRKU = LDA
- CHUNK = N
- LDWRKR = M
- ELSE
- *
- * WORK(IU) is M by CHUNK and WORK(IR) is M by M
- *
- LDWRKU = M
- CHUNK = ( LWORK-M*M-M ) / M
- LDWRKR = M
- END IF
- ITAU = IR + LDWRKR*M
- IWORK = ITAU + M
- *
- * Compute A=L*Q
- * (Workspace: need M*M+2*M, prefer M*M+M+M*NB)
- *
- CALL SGELQF( M, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Copy L to U, zeroing about above it
- *
- CALL SLACPY( 'L', M, M, A, LDA, U, LDU )
- CALL SLASET( 'U', M-1, M-1, ZERO, ZERO, U( 1, 2 ),
- $ LDU )
- *
- * Generate Q in A
- * (Workspace: need M*M+2*M, prefer M*M+M+M*NB)
- *
- CALL SORGLQ( M, N, M, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IE = ITAU
- ITAUQ = IE + M
- ITAUP = ITAUQ + M
- IWORK = ITAUP + M
- *
- * Bidiagonalize L in U, copying result to WORK(IR)
- * (Workspace: need M*M+4*M, prefer M*M+3*M+2*M*NB)
- *
- CALL SGEBRD( M, M, U, LDU, S, WORK( IE ),
- $ WORK( ITAUQ ), WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- CALL SLACPY( 'U', M, M, U, LDU, WORK( IR ), LDWRKR )
- *
- * Generate right vectors bidiagonalizing L in WORK(IR)
- * (Workspace: need M*M+4*M-1, prefer M*M+3*M+(M-1)*NB)
- *
- CALL SORGBR( 'P', M, M, M, WORK( IR ), LDWRKR,
- $ WORK( ITAUP ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- *
- * Generate left vectors bidiagonalizing L in U
- * (Workspace: need M*M+4*M, prefer M*M+3*M+M*NB)
- *
- CALL SORGBR( 'Q', M, M, M, U, LDU, WORK( ITAUQ ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IWORK = IE + M
- *
- * Perform bidiagonal QR iteration, computing left
- * singular vectors of L in U, and computing right
- * singular vectors of L in WORK(IR)
- * (Workspace: need M*M+BDSPAC)
- *
- CALL SBDSQR( 'U', M, M, M, 0, S, WORK( IE ),
- $ WORK( IR ), LDWRKR, U, LDU, DUM, 1,
- $ WORK( IWORK ), INFO )
- IU = IE + M
- *
- * Multiply right singular vectors of L in WORK(IR) by Q
- * in A, storing result in WORK(IU) and copying to A
- * (Workspace: need M*M+2*M, prefer M*M+M*N+M))
- *
- DO 40 I = 1, N, CHUNK
- BLK = MIN( N-I+1, CHUNK )
- CALL SGEMM( 'N', 'N', M, BLK, M, ONE, WORK( IR ),
- $ LDWRKR, A( 1, I ), LDA, ZERO,
- $ WORK( IU ), LDWRKU )
- CALL SLACPY( 'F', M, BLK, WORK( IU ), LDWRKU,
- $ A( 1, I ), LDA )
- 40 CONTINUE
- *
- ELSE
- *
- * Insufficient workspace for a fast algorithm
- *
- ITAU = 1
- IWORK = ITAU + M
- *
- * Compute A=L*Q
- * (Workspace: need 2*M, prefer M+M*NB)
- *
- CALL SGELQF( M, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Copy L to U, zeroing out above it
- *
- CALL SLACPY( 'L', M, M, A, LDA, U, LDU )
- CALL SLASET( 'U', M-1, M-1, ZERO, ZERO, U( 1, 2 ),
- $ LDU )
- *
- * Generate Q in A
- * (Workspace: need 2*M, prefer M+M*NB)
- *
- CALL SORGLQ( M, N, M, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IE = ITAU
- ITAUQ = IE + M
- ITAUP = ITAUQ + M
- IWORK = ITAUP + M
- *
- * Bidiagonalize L in U
- * (Workspace: need 4*M, prefer 3*M+2*M*NB)
- *
- CALL SGEBRD( M, M, U, LDU, S, WORK( IE ),
- $ WORK( ITAUQ ), WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Multiply right vectors bidiagonalizing L by Q in A
- * (Workspace: need 3*M+N, prefer 3*M+N*NB)
- *
- CALL SORMBR( 'P', 'L', 'T', M, N, M, U, LDU,
- $ WORK( ITAUP ), A, LDA, WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- *
- * Generate left vectors bidiagonalizing L in U
- * (Workspace: need 4*M, prefer 3*M+M*NB)
- *
- CALL SORGBR( 'Q', M, M, M, U, LDU, WORK( ITAUQ ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IWORK = IE + M
- *
- * Perform bidiagonal QR iteration, computing left
- * singular vectors of A in U and computing right
- * singular vectors of A in A
- * (Workspace: need BDSPAC)
- *
- CALL SBDSQR( 'U', M, N, M, 0, S, WORK( IE ), A, LDA,
- $ U, LDU, DUM, 1, WORK( IWORK ), INFO )
- *
- END IF
- *
- ELSE IF( WNTVS ) THEN
- *
- IF( WNTUN ) THEN
- *
- * Path 4t(N much larger than M, JOBU='N', JOBVT='S')
- * M right singular vectors to be computed in VT and
- * no left singular vectors to be computed
- *
- IF( LWORK.GE.M*M+MAX( 4*M, BDSPAC ) ) THEN
- *
- * Sufficient workspace for a fast algorithm
- *
- IR = 1
- IF( LWORK.GE.WRKBL+LDA*M ) THEN
- *
- * WORK(IR) is LDA by M
- *
- LDWRKR = LDA
- ELSE
- *
- * WORK(IR) is M by M
- *
- LDWRKR = M
- END IF
- ITAU = IR + LDWRKR*M
- IWORK = ITAU + M
- *
- * Compute A=L*Q
- * (Workspace: need M*M+2*M, prefer M*M+M+M*NB)
- *
- CALL SGELQF( M, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Copy L to WORK(IR), zeroing out above it
- *
- CALL SLACPY( 'L', M, M, A, LDA, WORK( IR ),
- $ LDWRKR )
- CALL SLASET( 'U', M-1, M-1, ZERO, ZERO,
- $ WORK( IR+LDWRKR ), LDWRKR )
- *
- * Generate Q in A
- * (Workspace: need M*M+2*M, prefer M*M+M+M*NB)
- *
- CALL SORGLQ( M, N, M, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IE = ITAU
- ITAUQ = IE + M
- ITAUP = ITAUQ + M
- IWORK = ITAUP + M
- *
- * Bidiagonalize L in WORK(IR)
- * (Workspace: need M*M+4*M, prefer M*M+3*M+2*M*NB)
- *
- CALL SGEBRD( M, M, WORK( IR ), LDWRKR, S,
- $ WORK( IE ), WORK( ITAUQ ),
- $ WORK( ITAUP ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- *
- * Generate right vectors bidiagonalizing L in
- * WORK(IR)
- * (Workspace: need M*M+4*M, prefer M*M+3*M+(M-1)*NB)
- *
- CALL SORGBR( 'P', M, M, M, WORK( IR ), LDWRKR,
- $ WORK( ITAUP ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- IWORK = IE + M
- *
- * Perform bidiagonal QR iteration, computing right
- * singular vectors of L in WORK(IR)
- * (Workspace: need M*M+BDSPAC)
- *
- CALL SBDSQR( 'U', M, M, 0, 0, S, WORK( IE ),
- $ WORK( IR ), LDWRKR, DUM, 1, DUM, 1,
- $ WORK( IWORK ), INFO )
- *
- * Multiply right singular vectors of L in WORK(IR) by
- * Q in A, storing result in VT
- * (Workspace: need M*M)
- *
- CALL SGEMM( 'N', 'N', M, N, M, ONE, WORK( IR ),
- $ LDWRKR, A, LDA, ZERO, VT, LDVT )
- *
- ELSE
- *
- * Insufficient workspace for a fast algorithm
- *
- ITAU = 1
- IWORK = ITAU + M
- *
- * Compute A=L*Q
- * (Workspace: need 2*M, prefer M+M*NB)
- *
- CALL SGELQF( M, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Copy result to VT
- *
- CALL SLACPY( 'U', M, N, A, LDA, VT, LDVT )
- *
- * Generate Q in VT
- * (Workspace: need 2*M, prefer M+M*NB)
- *
- CALL SORGLQ( M, N, M, VT, LDVT, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IE = ITAU
- ITAUQ = IE + M
- ITAUP = ITAUQ + M
- IWORK = ITAUP + M
- *
- * Zero out above L in A
- *
- CALL SLASET( 'U', M-1, M-1, ZERO, ZERO, A( 1, 2 ),
- $ LDA )
- *
- * Bidiagonalize L in A
- * (Workspace: need 4*M, prefer 3*M+2*M*NB)
- *
- CALL SGEBRD( M, M, A, LDA, S, WORK( IE ),
- $ WORK( ITAUQ ), WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Multiply right vectors bidiagonalizing L by Q in VT
- * (Workspace: need 3*M+N, prefer 3*M+N*NB)
- *
- CALL SORMBR( 'P', 'L', 'T', M, N, M, A, LDA,
- $ WORK( ITAUP ), VT, LDVT,
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IWORK = IE + M
- *
- * Perform bidiagonal QR iteration, computing right
- * singular vectors of A in VT
- * (Workspace: need BDSPAC)
- *
- CALL SBDSQR( 'U', M, N, 0, 0, S, WORK( IE ), VT,
- $ LDVT, DUM, 1, DUM, 1, WORK( IWORK ),
- $ INFO )
- *
- END IF
- *
- ELSE IF( WNTUO ) THEN
- *
- * Path 5t(N much larger than M, JOBU='O', JOBVT='S')
- * M right singular vectors to be computed in VT and
- * M left singular vectors to be overwritten on A
- *
- IF( LWORK.GE.2*M*M+MAX( 4*M, BDSPAC ) ) THEN
- *
- * Sufficient workspace for a fast algorithm
- *
- IU = 1
- IF( LWORK.GE.WRKBL+2*LDA*M ) THEN
- *
- * WORK(IU) is LDA by M and WORK(IR) is LDA by M
- *
- LDWRKU = LDA
- IR = IU + LDWRKU*M
- LDWRKR = LDA
- ELSE IF( LWORK.GE.WRKBL+( LDA+M )*M ) THEN
- *
- * WORK(IU) is LDA by M and WORK(IR) is M by M
- *
- LDWRKU = LDA
- IR = IU + LDWRKU*M
- LDWRKR = M
- ELSE
- *
- * WORK(IU) is M by M and WORK(IR) is M by M
- *
- LDWRKU = M
- IR = IU + LDWRKU*M
- LDWRKR = M
- END IF
- ITAU = IR + LDWRKR*M
- IWORK = ITAU + M
- *
- * Compute A=L*Q
- * (Workspace: need 2*M*M+2*M, prefer 2*M*M+M+M*NB)
- *
- CALL SGELQF( M, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Copy L to WORK(IU), zeroing out below it
- *
- CALL SLACPY( 'L', M, M, A, LDA, WORK( IU ),
- $ LDWRKU )
- CALL SLASET( 'U', M-1, M-1, ZERO, ZERO,
- $ WORK( IU+LDWRKU ), LDWRKU )
- *
- * Generate Q in A
- * (Workspace: need 2*M*M+2*M, prefer 2*M*M+M+M*NB)
- *
- CALL SORGLQ( M, N, M, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IE = ITAU
- ITAUQ = IE + M
- ITAUP = ITAUQ + M
- IWORK = ITAUP + M
- *
- * Bidiagonalize L in WORK(IU), copying result to
- * WORK(IR)
- * (Workspace: need 2*M*M+4*M,
- * prefer 2*M*M+3*M+2*M*NB)
- *
- CALL SGEBRD( M, M, WORK( IU ), LDWRKU, S,
- $ WORK( IE ), WORK( ITAUQ ),
- $ WORK( ITAUP ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- CALL SLACPY( 'L', M, M, WORK( IU ), LDWRKU,
- $ WORK( IR ), LDWRKR )
- *
- * Generate right bidiagonalizing vectors in WORK(IU)
- * (Workspace: need 2*M*M+4*M-1,
- * prefer 2*M*M+3*M+(M-1)*NB)
- *
- CALL SORGBR( 'P', M, M, M, WORK( IU ), LDWRKU,
- $ WORK( ITAUP ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- *
- * Generate left bidiagonalizing vectors in WORK(IR)
- * (Workspace: need 2*M*M+4*M, prefer 2*M*M+3*M+M*NB)
- *
- CALL SORGBR( 'Q', M, M, M, WORK( IR ), LDWRKR,
- $ WORK( ITAUQ ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- IWORK = IE + M
- *
- * Perform bidiagonal QR iteration, computing left
- * singular vectors of L in WORK(IR) and computing
- * right singular vectors of L in WORK(IU)
- * (Workspace: need 2*M*M+BDSPAC)
- *
- CALL SBDSQR( 'U', M, M, M, 0, S, WORK( IE ),
- $ WORK( IU ), LDWRKU, WORK( IR ),
- $ LDWRKR, DUM, 1, WORK( IWORK ), INFO )
- *
- * Multiply right singular vectors of L in WORK(IU) by
- * Q in A, storing result in VT
- * (Workspace: need M*M)
- *
- CALL SGEMM( 'N', 'N', M, N, M, ONE, WORK( IU ),
- $ LDWRKU, A, LDA, ZERO, VT, LDVT )
- *
- * Copy left singular vectors of L to A
- * (Workspace: need M*M)
- *
- CALL SLACPY( 'F', M, M, WORK( IR ), LDWRKR, A,
- $ LDA )
- *
- ELSE
- *
- * Insufficient workspace for a fast algorithm
- *
- ITAU = 1
- IWORK = ITAU + M
- *
- * Compute A=L*Q, copying result to VT
- * (Workspace: need 2*M, prefer M+M*NB)
- *
- CALL SGELQF( M, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- CALL SLACPY( 'U', M, N, A, LDA, VT, LDVT )
- *
- * Generate Q in VT
- * (Workspace: need 2*M, prefer M+M*NB)
- *
- CALL SORGLQ( M, N, M, VT, LDVT, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IE = ITAU
- ITAUQ = IE + M
- ITAUP = ITAUQ + M
- IWORK = ITAUP + M
- *
- * Zero out above L in A
- *
- CALL SLASET( 'U', M-1, M-1, ZERO, ZERO, A( 1, 2 ),
- $ LDA )
- *
- * Bidiagonalize L in A
- * (Workspace: need 4*M, prefer 3*M+2*M*NB)
- *
- CALL SGEBRD( M, M, A, LDA, S, WORK( IE ),
- $ WORK( ITAUQ ), WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Multiply right vectors bidiagonalizing L by Q in VT
- * (Workspace: need 3*M+N, prefer 3*M+N*NB)
- *
- CALL SORMBR( 'P', 'L', 'T', M, N, M, A, LDA,
- $ WORK( ITAUP ), VT, LDVT,
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Generate left bidiagonalizing vectors of L in A
- * (Workspace: need 4*M, prefer 3*M+M*NB)
- *
- CALL SORGBR( 'Q', M, M, M, A, LDA, WORK( ITAUQ ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IWORK = IE + M
- *
- * Perform bidiagonal QR iteration, compute left
- * singular vectors of A in A and compute right
- * singular vectors of A in VT
- * (Workspace: need BDSPAC)
- *
- CALL SBDSQR( 'U', M, N, M, 0, S, WORK( IE ), VT,
- $ LDVT, A, LDA, DUM, 1, WORK( IWORK ),
- $ INFO )
- *
- END IF
- *
- ELSE IF( WNTUAS ) THEN
- *
- * Path 6t(N much larger than M, JOBU='S' or 'A',
- * JOBVT='S')
- * M right singular vectors to be computed in VT and
- * M left singular vectors to be computed in U
- *
- IF( LWORK.GE.M*M+MAX( 4*M, BDSPAC ) ) THEN
- *
- * Sufficient workspace for a fast algorithm
- *
- IU = 1
- IF( LWORK.GE.WRKBL+LDA*M ) THEN
- *
- * WORK(IU) is LDA by N
- *
- LDWRKU = LDA
- ELSE
- *
- * WORK(IU) is LDA by M
- *
- LDWRKU = M
- END IF
- ITAU = IU + LDWRKU*M
- IWORK = ITAU + M
- *
- * Compute A=L*Q
- * (Workspace: need M*M+2*M, prefer M*M+M+M*NB)
- *
- CALL SGELQF( M, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Copy L to WORK(IU), zeroing out above it
- *
- CALL SLACPY( 'L', M, M, A, LDA, WORK( IU ),
- $ LDWRKU )
- CALL SLASET( 'U', M-1, M-1, ZERO, ZERO,
- $ WORK( IU+LDWRKU ), LDWRKU )
- *
- * Generate Q in A
- * (Workspace: need M*M+2*M, prefer M*M+M+M*NB)
- *
- CALL SORGLQ( M, N, M, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IE = ITAU
- ITAUQ = IE + M
- ITAUP = ITAUQ + M
- IWORK = ITAUP + M
- *
- * Bidiagonalize L in WORK(IU), copying result to U
- * (Workspace: need M*M+4*M, prefer M*M+3*M+2*M*NB)
- *
- CALL SGEBRD( M, M, WORK( IU ), LDWRKU, S,
- $ WORK( IE ), WORK( ITAUQ ),
- $ WORK( ITAUP ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- CALL SLACPY( 'L', M, M, WORK( IU ), LDWRKU, U,
- $ LDU )
- *
- * Generate right bidiagonalizing vectors in WORK(IU)
- * (Workspace: need M*M+4*M-1,
- * prefer M*M+3*M+(M-1)*NB)
- *
- CALL SORGBR( 'P', M, M, M, WORK( IU ), LDWRKU,
- $ WORK( ITAUP ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- *
- * Generate left bidiagonalizing vectors in U
- * (Workspace: need M*M+4*M, prefer M*M+3*M+M*NB)
- *
- CALL SORGBR( 'Q', M, M, M, U, LDU, WORK( ITAUQ ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IWORK = IE + M
- *
- * Perform bidiagonal QR iteration, computing left
- * singular vectors of L in U and computing right
- * singular vectors of L in WORK(IU)
- * (Workspace: need M*M+BDSPAC)
- *
- CALL SBDSQR( 'U', M, M, M, 0, S, WORK( IE ),
- $ WORK( IU ), LDWRKU, U, LDU, DUM, 1,
- $ WORK( IWORK ), INFO )
- *
- * Multiply right singular vectors of L in WORK(IU) by
- * Q in A, storing result in VT
- * (Workspace: need M*M)
- *
- CALL SGEMM( 'N', 'N', M, N, M, ONE, WORK( IU ),
- $ LDWRKU, A, LDA, ZERO, VT, LDVT )
- *
- ELSE
- *
- * Insufficient workspace for a fast algorithm
- *
- ITAU = 1
- IWORK = ITAU + M
- *
- * Compute A=L*Q, copying result to VT
- * (Workspace: need 2*M, prefer M+M*NB)
- *
- CALL SGELQF( M, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- CALL SLACPY( 'U', M, N, A, LDA, VT, LDVT )
- *
- * Generate Q in VT
- * (Workspace: need 2*M, prefer M+M*NB)
- *
- CALL SORGLQ( M, N, M, VT, LDVT, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Copy L to U, zeroing out above it
- *
- CALL SLACPY( 'L', M, M, A, LDA, U, LDU )
- CALL SLASET( 'U', M-1, M-1, ZERO, ZERO, U( 1, 2 ),
- $ LDU )
- IE = ITAU
- ITAUQ = IE + M
- ITAUP = ITAUQ + M
- IWORK = ITAUP + M
- *
- * Bidiagonalize L in U
- * (Workspace: need 4*M, prefer 3*M+2*M*NB)
- *
- CALL SGEBRD( M, M, U, LDU, S, WORK( IE ),
- $ WORK( ITAUQ ), WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Multiply right bidiagonalizing vectors in U by Q
- * in VT
- * (Workspace: need 3*M+N, prefer 3*M+N*NB)
- *
- CALL SORMBR( 'P', 'L', 'T', M, N, M, U, LDU,
- $ WORK( ITAUP ), VT, LDVT,
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Generate left bidiagonalizing vectors in U
- * (Workspace: need 4*M, prefer 3*M+M*NB)
- *
- CALL SORGBR( 'Q', M, M, M, U, LDU, WORK( ITAUQ ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IWORK = IE + M
- *
- * Perform bidiagonal QR iteration, computing left
- * singular vectors of A in U and computing right
- * singular vectors of A in VT
- * (Workspace: need BDSPAC)
- *
- CALL SBDSQR( 'U', M, N, M, 0, S, WORK( IE ), VT,
- $ LDVT, U, LDU, DUM, 1, WORK( IWORK ),
- $ INFO )
- *
- END IF
- *
- END IF
- *
- ELSE IF( WNTVA ) THEN
- *
- IF( WNTUN ) THEN
- *
- * Path 7t(N much larger than M, JOBU='N', JOBVT='A')
- * N right singular vectors to be computed in VT and
- * no left singular vectors to be computed
- *
- IF( LWORK.GE.M*M+MAX( N+M, 4*M, BDSPAC ) ) THEN
- *
- * Sufficient workspace for a fast algorithm
- *
- IR = 1
- IF( LWORK.GE.WRKBL+LDA*M ) THEN
- *
- * WORK(IR) is LDA by M
- *
- LDWRKR = LDA
- ELSE
- *
- * WORK(IR) is M by M
- *
- LDWRKR = M
- END IF
- ITAU = IR + LDWRKR*M
- IWORK = ITAU + M
- *
- * Compute A=L*Q, copying result to VT
- * (Workspace: need M*M+2*M, prefer M*M+M+M*NB)
- *
- CALL SGELQF( M, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- CALL SLACPY( 'U', M, N, A, LDA, VT, LDVT )
- *
- * Copy L to WORK(IR), zeroing out above it
- *
- CALL SLACPY( 'L', M, M, A, LDA, WORK( IR ),
- $ LDWRKR )
- CALL SLASET( 'U', M-1, M-1, ZERO, ZERO,
- $ WORK( IR+LDWRKR ), LDWRKR )
- *
- * Generate Q in VT
- * (Workspace: need M*M+M+N, prefer M*M+M+N*NB)
- *
- CALL SORGLQ( N, N, M, VT, LDVT, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IE = ITAU
- ITAUQ = IE + M
- ITAUP = ITAUQ + M
- IWORK = ITAUP + M
- *
- * Bidiagonalize L in WORK(IR)
- * (Workspace: need M*M+4*M, prefer M*M+3*M+2*M*NB)
- *
- CALL SGEBRD( M, M, WORK( IR ), LDWRKR, S,
- $ WORK( IE ), WORK( ITAUQ ),
- $ WORK( ITAUP ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- *
- * Generate right bidiagonalizing vectors in WORK(IR)
- * (Workspace: need M*M+4*M-1,
- * prefer M*M+3*M+(M-1)*NB)
- *
- CALL SORGBR( 'P', M, M, M, WORK( IR ), LDWRKR,
- $ WORK( ITAUP ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- IWORK = IE + M
- *
- * Perform bidiagonal QR iteration, computing right
- * singular vectors of L in WORK(IR)
- * (Workspace: need M*M+BDSPAC)
- *
- CALL SBDSQR( 'U', M, M, 0, 0, S, WORK( IE ),
- $ WORK( IR ), LDWRKR, DUM, 1, DUM, 1,
- $ WORK( IWORK ), INFO )
- *
- * Multiply right singular vectors of L in WORK(IR) by
- * Q in VT, storing result in A
- * (Workspace: need M*M)
- *
- CALL SGEMM( 'N', 'N', M, N, M, ONE, WORK( IR ),
- $ LDWRKR, VT, LDVT, ZERO, A, LDA )
- *
- * Copy right singular vectors of A from A to VT
- *
- CALL SLACPY( 'F', M, N, A, LDA, VT, LDVT )
- *
- ELSE
- *
- * Insufficient workspace for a fast algorithm
- *
- ITAU = 1
- IWORK = ITAU + M
- *
- * Compute A=L*Q, copying result to VT
- * (Workspace: need 2*M, prefer M+M*NB)
- *
- CALL SGELQF( M, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- CALL SLACPY( 'U', M, N, A, LDA, VT, LDVT )
- *
- * Generate Q in VT
- * (Workspace: need M+N, prefer M+N*NB)
- *
- CALL SORGLQ( N, N, M, VT, LDVT, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IE = ITAU
- ITAUQ = IE + M
- ITAUP = ITAUQ + M
- IWORK = ITAUP + M
- *
- * Zero out above L in A
- *
- CALL SLASET( 'U', M-1, M-1, ZERO, ZERO, A( 1, 2 ),
- $ LDA )
- *
- * Bidiagonalize L in A
- * (Workspace: need 4*M, prefer 3*M+2*M*NB)
- *
- CALL SGEBRD( M, M, A, LDA, S, WORK( IE ),
- $ WORK( ITAUQ ), WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Multiply right bidiagonalizing vectors in A by Q
- * in VT
- * (Workspace: need 3*M+N, prefer 3*M+N*NB)
- *
- CALL SORMBR( 'P', 'L', 'T', M, N, M, A, LDA,
- $ WORK( ITAUP ), VT, LDVT,
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IWORK = IE + M
- *
- * Perform bidiagonal QR iteration, computing right
- * singular vectors of A in VT
- * (Workspace: need BDSPAC)
- *
- CALL SBDSQR( 'U', M, N, 0, 0, S, WORK( IE ), VT,
- $ LDVT, DUM, 1, DUM, 1, WORK( IWORK ),
- $ INFO )
- *
- END IF
- *
- ELSE IF( WNTUO ) THEN
- *
- * Path 8t(N much larger than M, JOBU='O', JOBVT='A')
- * N right singular vectors to be computed in VT and
- * M left singular vectors to be overwritten on A
- *
- IF( LWORK.GE.2*M*M+MAX( N+M, 4*M, BDSPAC ) ) THEN
- *
- * Sufficient workspace for a fast algorithm
- *
- IU = 1
- IF( LWORK.GE.WRKBL+2*LDA*M ) THEN
- *
- * WORK(IU) is LDA by M and WORK(IR) is LDA by M
- *
- LDWRKU = LDA
- IR = IU + LDWRKU*M
- LDWRKR = LDA
- ELSE IF( LWORK.GE.WRKBL+( LDA+M )*M ) THEN
- *
- * WORK(IU) is LDA by M and WORK(IR) is M by M
- *
- LDWRKU = LDA
- IR = IU + LDWRKU*M
- LDWRKR = M
- ELSE
- *
- * WORK(IU) is M by M and WORK(IR) is M by M
- *
- LDWRKU = M
- IR = IU + LDWRKU*M
- LDWRKR = M
- END IF
- ITAU = IR + LDWRKR*M
- IWORK = ITAU + M
- *
- * Compute A=L*Q, copying result to VT
- * (Workspace: need 2*M*M+2*M, prefer 2*M*M+M+M*NB)
- *
- CALL SGELQF( M, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- CALL SLACPY( 'U', M, N, A, LDA, VT, LDVT )
- *
- * Generate Q in VT
- * (Workspace: need 2*M*M+M+N, prefer 2*M*M+M+N*NB)
- *
- CALL SORGLQ( N, N, M, VT, LDVT, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Copy L to WORK(IU), zeroing out above it
- *
- CALL SLACPY( 'L', M, M, A, LDA, WORK( IU ),
- $ LDWRKU )
- CALL SLASET( 'U', M-1, M-1, ZERO, ZERO,
- $ WORK( IU+LDWRKU ), LDWRKU )
- IE = ITAU
- ITAUQ = IE + M
- ITAUP = ITAUQ + M
- IWORK = ITAUP + M
- *
- * Bidiagonalize L in WORK(IU), copying result to
- * WORK(IR)
- * (Workspace: need 2*M*M+4*M,
- * prefer 2*M*M+3*M+2*M*NB)
- *
- CALL SGEBRD( M, M, WORK( IU ), LDWRKU, S,
- $ WORK( IE ), WORK( ITAUQ ),
- $ WORK( ITAUP ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- CALL SLACPY( 'L', M, M, WORK( IU ), LDWRKU,
- $ WORK( IR ), LDWRKR )
- *
- * Generate right bidiagonalizing vectors in WORK(IU)
- * (Workspace: need 2*M*M+4*M-1,
- * prefer 2*M*M+3*M+(M-1)*NB)
- *
- CALL SORGBR( 'P', M, M, M, WORK( IU ), LDWRKU,
- $ WORK( ITAUP ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- *
- * Generate left bidiagonalizing vectors in WORK(IR)
- * (Workspace: need 2*M*M+4*M, prefer 2*M*M+3*M+M*NB)
- *
- CALL SORGBR( 'Q', M, M, M, WORK( IR ), LDWRKR,
- $ WORK( ITAUQ ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- IWORK = IE + M
- *
- * Perform bidiagonal QR iteration, computing left
- * singular vectors of L in WORK(IR) and computing
- * right singular vectors of L in WORK(IU)
- * (Workspace: need 2*M*M+BDSPAC)
- *
- CALL SBDSQR( 'U', M, M, M, 0, S, WORK( IE ),
- $ WORK( IU ), LDWRKU, WORK( IR ),
- $ LDWRKR, DUM, 1, WORK( IWORK ), INFO )
- *
- * Multiply right singular vectors of L in WORK(IU) by
- * Q in VT, storing result in A
- * (Workspace: need M*M)
- *
- CALL SGEMM( 'N', 'N', M, N, M, ONE, WORK( IU ),
- $ LDWRKU, VT, LDVT, ZERO, A, LDA )
- *
- * Copy right singular vectors of A from A to VT
- *
- CALL SLACPY( 'F', M, N, A, LDA, VT, LDVT )
- *
- * Copy left singular vectors of A from WORK(IR) to A
- *
- CALL SLACPY( 'F', M, M, WORK( IR ), LDWRKR, A,
- $ LDA )
- *
- ELSE
- *
- * Insufficient workspace for a fast algorithm
- *
- ITAU = 1
- IWORK = ITAU + M
- *
- * Compute A=L*Q, copying result to VT
- * (Workspace: need 2*M, prefer M+M*NB)
- *
- CALL SGELQF( M, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- CALL SLACPY( 'U', M, N, A, LDA, VT, LDVT )
- *
- * Generate Q in VT
- * (Workspace: need M+N, prefer M+N*NB)
- *
- CALL SORGLQ( N, N, M, VT, LDVT, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IE = ITAU
- ITAUQ = IE + M
- ITAUP = ITAUQ + M
- IWORK = ITAUP + M
- *
- * Zero out above L in A
- *
- CALL SLASET( 'U', M-1, M-1, ZERO, ZERO, A( 1, 2 ),
- $ LDA )
- *
- * Bidiagonalize L in A
- * (Workspace: need 4*M, prefer 3*M+2*M*NB)
- *
- CALL SGEBRD( M, M, A, LDA, S, WORK( IE ),
- $ WORK( ITAUQ ), WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Multiply right bidiagonalizing vectors in A by Q
- * in VT
- * (Workspace: need 3*M+N, prefer 3*M+N*NB)
- *
- CALL SORMBR( 'P', 'L', 'T', M, N, M, A, LDA,
- $ WORK( ITAUP ), VT, LDVT,
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Generate left bidiagonalizing vectors in A
- * (Workspace: need 4*M, prefer 3*M+M*NB)
- *
- CALL SORGBR( 'Q', M, M, M, A, LDA, WORK( ITAUQ ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IWORK = IE + M
- *
- * Perform bidiagonal QR iteration, computing left
- * singular vectors of A in A and computing right
- * singular vectors of A in VT
- * (Workspace: need BDSPAC)
- *
- CALL SBDSQR( 'U', M, N, M, 0, S, WORK( IE ), VT,
- $ LDVT, A, LDA, DUM, 1, WORK( IWORK ),
- $ INFO )
- *
- END IF
- *
- ELSE IF( WNTUAS ) THEN
- *
- * Path 9t(N much larger than M, JOBU='S' or 'A',
- * JOBVT='A')
- * N right singular vectors to be computed in VT and
- * M left singular vectors to be computed in U
- *
- IF( LWORK.GE.M*M+MAX( N+M, 4*M, BDSPAC ) ) THEN
- *
- * Sufficient workspace for a fast algorithm
- *
- IU = 1
- IF( LWORK.GE.WRKBL+LDA*M ) THEN
- *
- * WORK(IU) is LDA by M
- *
- LDWRKU = LDA
- ELSE
- *
- * WORK(IU) is M by M
- *
- LDWRKU = M
- END IF
- ITAU = IU + LDWRKU*M
- IWORK = ITAU + M
- *
- * Compute A=L*Q, copying result to VT
- * (Workspace: need M*M+2*M, prefer M*M+M+M*NB)
- *
- CALL SGELQF( M, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- CALL SLACPY( 'U', M, N, A, LDA, VT, LDVT )
- *
- * Generate Q in VT
- * (Workspace: need M*M+M+N, prefer M*M+M+N*NB)
- *
- CALL SORGLQ( N, N, M, VT, LDVT, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Copy L to WORK(IU), zeroing out above it
- *
- CALL SLACPY( 'L', M, M, A, LDA, WORK( IU ),
- $ LDWRKU )
- CALL SLASET( 'U', M-1, M-1, ZERO, ZERO,
- $ WORK( IU+LDWRKU ), LDWRKU )
- IE = ITAU
- ITAUQ = IE + M
- ITAUP = ITAUQ + M
- IWORK = ITAUP + M
- *
- * Bidiagonalize L in WORK(IU), copying result to U
- * (Workspace: need M*M+4*M, prefer M*M+3*M+2*M*NB)
- *
- CALL SGEBRD( M, M, WORK( IU ), LDWRKU, S,
- $ WORK( IE ), WORK( ITAUQ ),
- $ WORK( ITAUP ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- CALL SLACPY( 'L', M, M, WORK( IU ), LDWRKU, U,
- $ LDU )
- *
- * Generate right bidiagonalizing vectors in WORK(IU)
- * (Workspace: need M*M+4*M, prefer M*M+3*M+(M-1)*NB)
- *
- CALL SORGBR( 'P', M, M, M, WORK( IU ), LDWRKU,
- $ WORK( ITAUP ), WORK( IWORK ),
- $ LWORK-IWORK+1, IERR )
- *
- * Generate left bidiagonalizing vectors in U
- * (Workspace: need M*M+4*M, prefer M*M+3*M+M*NB)
- *
- CALL SORGBR( 'Q', M, M, M, U, LDU, WORK( ITAUQ ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IWORK = IE + M
- *
- * Perform bidiagonal QR iteration, computing left
- * singular vectors of L in U and computing right
- * singular vectors of L in WORK(IU)
- * (Workspace: need M*M+BDSPAC)
- *
- CALL SBDSQR( 'U', M, M, M, 0, S, WORK( IE ),
- $ WORK( IU ), LDWRKU, U, LDU, DUM, 1,
- $ WORK( IWORK ), INFO )
- *
- * Multiply right singular vectors of L in WORK(IU) by
- * Q in VT, storing result in A
- * (Workspace: need M*M)
- *
- CALL SGEMM( 'N', 'N', M, N, M, ONE, WORK( IU ),
- $ LDWRKU, VT, LDVT, ZERO, A, LDA )
- *
- * Copy right singular vectors of A from A to VT
- *
- CALL SLACPY( 'F', M, N, A, LDA, VT, LDVT )
- *
- ELSE
- *
- * Insufficient workspace for a fast algorithm
- *
- ITAU = 1
- IWORK = ITAU + M
- *
- * Compute A=L*Q, copying result to VT
- * (Workspace: need 2*M, prefer M+M*NB)
- *
- CALL SGELQF( M, N, A, LDA, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- CALL SLACPY( 'U', M, N, A, LDA, VT, LDVT )
- *
- * Generate Q in VT
- * (Workspace: need M+N, prefer M+N*NB)
- *
- CALL SORGLQ( N, N, M, VT, LDVT, WORK( ITAU ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Copy L to U, zeroing out above it
- *
- CALL SLACPY( 'L', M, M, A, LDA, U, LDU )
- CALL SLASET( 'U', M-1, M-1, ZERO, ZERO, U( 1, 2 ),
- $ LDU )
- IE = ITAU
- ITAUQ = IE + M
- ITAUP = ITAUQ + M
- IWORK = ITAUP + M
- *
- * Bidiagonalize L in U
- * (Workspace: need 4*M, prefer 3*M+2*M*NB)
- *
- CALL SGEBRD( M, M, U, LDU, S, WORK( IE ),
- $ WORK( ITAUQ ), WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Multiply right bidiagonalizing vectors in U by Q
- * in VT
- * (Workspace: need 3*M+N, prefer 3*M+N*NB)
- *
- CALL SORMBR( 'P', 'L', 'T', M, N, M, U, LDU,
- $ WORK( ITAUP ), VT, LDVT,
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- *
- * Generate left bidiagonalizing vectors in U
- * (Workspace: need 4*M, prefer 3*M+M*NB)
- *
- CALL SORGBR( 'Q', M, M, M, U, LDU, WORK( ITAUQ ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- IWORK = IE + M
- *
- * Perform bidiagonal QR iteration, computing left
- * singular vectors of A in U and computing right
- * singular vectors of A in VT
- * (Workspace: need BDSPAC)
- *
- CALL SBDSQR( 'U', M, N, M, 0, S, WORK( IE ), VT,
- $ LDVT, U, LDU, DUM, 1, WORK( IWORK ),
- $ INFO )
- *
- END IF
- *
- END IF
- *
- END IF
- *
- ELSE
- *
- * N .LT. MNTHR
- *
- * Path 10t(N greater than M, but not much larger)
- * Reduce to bidiagonal form without LQ decomposition
- *
- IE = 1
- ITAUQ = IE + M
- ITAUP = ITAUQ + M
- IWORK = ITAUP + M
- *
- * Bidiagonalize A
- * (Workspace: need 3*M+N, prefer 3*M+(M+N)*NB)
- *
- CALL SGEBRD( M, N, A, LDA, S, WORK( IE ), WORK( ITAUQ ),
- $ WORK( ITAUP ), WORK( IWORK ), LWORK-IWORK+1,
- $ IERR )
- IF( WNTUAS ) THEN
- *
- * If left singular vectors desired in U, copy result to U
- * and generate left bidiagonalizing vectors in U
- * (Workspace: need 4*M-1, prefer 3*M+(M-1)*NB)
- *
- CALL SLACPY( 'L', M, M, A, LDA, U, LDU )
- CALL SORGBR( 'Q', M, M, N, U, LDU, WORK( ITAUQ ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- END IF
- IF( WNTVAS ) THEN
- *
- * If right singular vectors desired in VT, copy result to
- * VT and generate right bidiagonalizing vectors in VT
- * (Workspace: need 3*M+NRVT, prefer 3*M+NRVT*NB)
- *
- CALL SLACPY( 'U', M, N, A, LDA, VT, LDVT )
- IF( WNTVA )
- $ NRVT = N
- IF( WNTVS )
- $ NRVT = M
- CALL SORGBR( 'P', NRVT, N, M, VT, LDVT, WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- END IF
- IF( WNTUO ) THEN
- *
- * If left singular vectors desired in A, generate left
- * bidiagonalizing vectors in A
- * (Workspace: need 4*M-1, prefer 3*M+(M-1)*NB)
- *
- CALL SORGBR( 'Q', M, M, N, A, LDA, WORK( ITAUQ ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- END IF
- IF( WNTVO ) THEN
- *
- * If right singular vectors desired in A, generate right
- * bidiagonalizing vectors in A
- * (Workspace: need 4*M, prefer 3*M+M*NB)
- *
- CALL SORGBR( 'P', M, N, M, A, LDA, WORK( ITAUP ),
- $ WORK( IWORK ), LWORK-IWORK+1, IERR )
- END IF
- IWORK = IE + M
- IF( WNTUAS .OR. WNTUO )
- $ NRU = M
- IF( WNTUN )
- $ NRU = 0
- IF( WNTVAS .OR. WNTVO )
- $ NCVT = N
- IF( WNTVN )
- $ NCVT = 0
- IF( ( .NOT.WNTUO ) .AND. ( .NOT.WNTVO ) ) THEN
- *
- * Perform bidiagonal QR iteration, if desired, computing
- * left singular vectors in U and computing right singular
- * vectors in VT
- * (Workspace: need BDSPAC)
- *
- CALL SBDSQR( 'L', M, NCVT, NRU, 0, S, WORK( IE ), VT,
- $ LDVT, U, LDU, DUM, 1, WORK( IWORK ), INFO )
- ELSE IF( ( .NOT.WNTUO ) .AND. WNTVO ) THEN
- *
- * Perform bidiagonal QR iteration, if desired, computing
- * left singular vectors in U and computing right singular
- * vectors in A
- * (Workspace: need BDSPAC)
- *
- CALL SBDSQR( 'L', M, NCVT, NRU, 0, S, WORK( IE ), A, LDA,
- $ U, LDU, DUM, 1, WORK( IWORK ), INFO )
- ELSE
- *
- * Perform bidiagonal QR iteration, if desired, computing
- * left singular vectors in A and computing right singular
- * vectors in VT
- * (Workspace: need BDSPAC)
- *
- CALL SBDSQR( 'L', M, NCVT, NRU, 0, S, WORK( IE ), VT,
- $ LDVT, A, LDA, DUM, 1, WORK( IWORK ), INFO )
- END IF
- *
- END IF
- *
- END IF
- *
- * If SBDSQR failed to converge, copy unconverged superdiagonals
- * to WORK( 2:MINMN )
- *
- IF( INFO.NE.0 ) THEN
- IF( IE.GT.2 ) THEN
- DO 50 I = 1, MINMN - 1
- WORK( I+1 ) = WORK( I+IE-1 )
- 50 CONTINUE
- END IF
- IF( IE.LT.2 ) THEN
- DO 60 I = MINMN - 1, 1, -1
- WORK( I+1 ) = WORK( I+IE-1 )
- 60 CONTINUE
- END IF
- END IF
- *
- * Undo scaling if necessary
- *
- IF( ISCL.EQ.1 ) THEN
- IF( ANRM.GT.BIGNUM )
- $ CALL SLASCL( 'G', 0, 0, BIGNUM, ANRM, MINMN, 1, S, MINMN,
- $ IERR )
- IF( INFO.NE.0 .AND. ANRM.GT.BIGNUM )
- $ CALL SLASCL( 'G', 0, 0, BIGNUM, ANRM, MINMN-1, 1, WORK( 2 ),
- $ MINMN, IERR )
- IF( ANRM.LT.SMLNUM )
- $ CALL SLASCL( 'G', 0, 0, SMLNUM, ANRM, MINMN, 1, S, MINMN,
- $ IERR )
- IF( INFO.NE.0 .AND. ANRM.LT.SMLNUM )
- $ CALL SLASCL( 'G', 0, 0, SMLNUM, ANRM, MINMN-1, 1, WORK( 2 ),
- $ MINMN, IERR )
- END IF
- *
- * Return optimal workspace in WORK(1)
- *
- WORK( 1 ) = SROUNDUP_LWORK(MAXWRK)
- *
- RETURN
- *
- * End of SGESVD
- *
- END
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