diff options
Diffstat (limited to 'SRC/sgesvd.f')
| -rw-r--r-- | SRC/sgesvd.f | 3402 |
1 files changed, 3402 insertions, 0 deletions
diff --git a/SRC/sgesvd.f b/SRC/sgesvd.f new file mode 100644 index 00000000..6217d039 --- /dev/null +++ b/SRC/sgesvd.f @@ -0,0 +1,3402 @@ + SUBROUTINE SGESVD( JOBU, JOBVT, M, N, A, LDA, S, U, LDU, VT, LDVT, + $ WORK, LWORK, INFO ) +* +* -- LAPACK driver routine (version 3.1) -- +* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. +* November 2006 +* +* .. Scalar Arguments .. + CHARACTER JOBU, JOBVT + INTEGER INFO, LDA, LDU, LDVT, LWORK, M, N +* .. +* .. Array Arguments .. + REAL A( LDA, * ), S( * ), U( LDU, * ), + $ VT( LDVT, * ), WORK( * ) +* .. +* +* Purpose +* ======= +* +* 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. +* +* Arguments +* ========= +* +* JOBU (input) 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. +* +* JOBVT (input) 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'. +* +* M (input) INTEGER +* The number of rows of the input matrix A. M >= 0. +* +* N (input) INTEGER +* The number of columns of the input matrix A. N >= 0. +* +* A (input/output) 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. +* +* LDA (input) INTEGER +* The leading dimension of the array A. LDA >= max(1,M). +* +* S (output) REAL array, dimension (min(M,N)) +* The singular values of A, sorted so that S(i) >= S(i+1). +* +* U (output) 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. +* +* LDU (input) INTEGER +* The leading dimension of the array U. LDU >= 1; if +* JOBU = 'S' or 'A', LDU >= M. +* +* VT (output) 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. +* +* LDVT (input) INTEGER +* The leading dimension of the array VT. LDVT >= 1; if +* JOBVT = 'A', LDVT >= N; if JOBVT = 'S', LDVT >= min(M,N). +* +* WORK (workspace/output) 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. +* +* LWORK (input) INTEGER +* The dimension of the array WORK. +* LWORK >= MAX(1,3*MIN(M,N)+MAX(M,N),5*MIN(M,N)). +* 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. +* +* INFO (output) 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. +* +* ===================================================================== +* +* .. 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 + 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 + EXTERNAL LSAME, ILAENV, SLAMCH, SLANGE +* .. +* .. 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 + IF( M.GE.MNTHR ) THEN + IF( WNTUN ) THEN +* +* Path 1 (M much larger than N, JOBU='N') +* + MAXWRK = N + N*ILAENV( 1, 'SGEQRF', ' ', M, N, -1, + $ -1 ) + MAXWRK = MAX( MAXWRK, 3*N+2*N* + $ ILAENV( 1, 'SGEBRD', ' ', N, N, -1, -1 ) ) + IF( WNTVO .OR. WNTVAS ) + $ MAXWRK = MAX( MAXWRK, 3*N+( N-1 )* + $ ILAENV( 1, 'SORGBR', 'P', N, N, N, -1 ) ) + 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 + N*ILAENV( 1, 'SGEQRF', ' ', M, N, -1, -1 ) + WRKBL = MAX( WRKBL, N+N*ILAENV( 1, 'SORGQR', ' ', M, + $ N, N, -1 ) ) + WRKBL = MAX( WRKBL, 3*N+2*N* + $ ILAENV( 1, 'SGEBRD', ' ', N, N, -1, -1 ) ) + WRKBL = MAX( WRKBL, 3*N+N* + $ ILAENV( 1, 'SORGBR', 'Q', N, N, N, -1 ) ) + 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 + N*ILAENV( 1, 'SGEQRF', ' ', M, N, -1, -1 ) + WRKBL = MAX( WRKBL, N+N*ILAENV( 1, 'SORGQR', ' ', M, + $ N, N, -1 ) ) + WRKBL = MAX( WRKBL, 3*N+2*N* + $ ILAENV( 1, 'SGEBRD', ' ', N, N, -1, -1 ) ) + WRKBL = MAX( WRKBL, 3*N+N* + $ ILAENV( 1, 'SORGBR', 'Q', N, N, N, -1 ) ) + WRKBL = MAX( WRKBL, 3*N+( N-1 )* + $ ILAENV( 1, 'SORGBR', 'P', N, N, N, -1 ) ) + 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 + N*ILAENV( 1, 'SGEQRF', ' ', M, N, -1, -1 ) + WRKBL = MAX( WRKBL, N+N*ILAENV( 1, 'SORGQR', ' ', M, + $ N, N, -1 ) ) + WRKBL = MAX( WRKBL, 3*N+2*N* + $ ILAENV( 1, 'SGEBRD', ' ', N, N, -1, -1 ) ) + WRKBL = MAX( WRKBL, 3*N+N* + $ ILAENV( 1, 'SORGBR', 'Q', N, N, N, -1 ) ) + 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 + N*ILAENV( 1, 'SGEQRF', ' ', M, N, -1, -1 ) + WRKBL = MAX( WRKBL, N+N*ILAENV( 1, 'SORGQR', ' ', M, + $ N, N, -1 ) ) + WRKBL = MAX( WRKBL, 3*N+2*N* + $ ILAENV( 1, 'SGEBRD', ' ', N, N, -1, -1 ) ) + WRKBL = MAX( WRKBL, 3*N+N* + $ ILAENV( 1, 'SORGBR', 'Q', N, N, N, -1 ) ) + WRKBL = MAX( WRKBL, 3*N+( N-1 )* + $ ILAENV( 1, 'SORGBR', 'P', N, N, N, -1 ) ) + 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 + N*ILAENV( 1, 'SGEQRF', ' ', M, N, -1, -1 ) + WRKBL = MAX( WRKBL, N+N*ILAENV( 1, 'SORGQR', ' ', M, + $ N, N, -1 ) ) + WRKBL = MAX( WRKBL, 3*N+2*N* + $ ILAENV( 1, 'SGEBRD', ' ', N, N, -1, -1 ) ) + WRKBL = MAX( WRKBL, 3*N+N* + $ ILAENV( 1, 'SORGBR', 'Q', N, N, N, -1 ) ) + WRKBL = MAX( WRKBL, 3*N+( N-1 )* + $ ILAENV( 1, 'SORGBR', 'P', N, N, N, -1 ) ) + 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 + N*ILAENV( 1, 'SGEQRF', ' ', M, N, -1, -1 ) + WRKBL = MAX( WRKBL, N+M*ILAENV( 1, 'SORGQR', ' ', M, + $ M, N, -1 ) ) + WRKBL = MAX( WRKBL, 3*N+2*N* + $ ILAENV( 1, 'SGEBRD', ' ', N, N, -1, -1 ) ) + WRKBL = MAX( WRKBL, 3*N+N* + $ ILAENV( 1, 'SORGBR', 'Q', N, N, N, -1 ) ) + 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 + N*ILAENV( 1, 'SGEQRF', ' ', M, N, -1, -1 ) + WRKBL = MAX( WRKBL, N+M*ILAENV( 1, 'SORGQR', ' ', M, + $ M, N, -1 ) ) + WRKBL = MAX( WRKBL, 3*N+2*N* + $ ILAENV( 1, 'SGEBRD', ' ', N, N, -1, -1 ) ) + WRKBL = MAX( WRKBL, 3*N+N* + $ ILAENV( 1, 'SORGBR', 'Q', N, N, N, -1 ) ) + WRKBL = MAX( WRKBL, 3*N+( N-1 )* + $ ILAENV( 1, 'SORGBR', 'P', N, N, N, -1 ) ) + 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 + N*ILAENV( 1, 'SGEQRF', ' ', M, N, -1, -1 ) + WRKBL = MAX( WRKBL, N+M*ILAENV( 1, 'SORGQR', ' ', M, + $ M, N, -1 ) ) + WRKBL = MAX( WRKBL, 3*N+2*N* + $ ILAENV( 1, 'SGEBRD', ' ', N, N, -1, -1 ) ) + WRKBL = MAX( WRKBL, 3*N+N* + $ ILAENV( 1, 'SORGBR', 'Q', N, N, N, -1 ) ) + WRKBL = MAX( WRKBL, 3*N+( N-1 )* + $ ILAENV( 1, 'SORGBR', 'P', N, N, N, -1 ) ) + 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) +* + MAXWRK = 3*N + ( M+N )*ILAENV( 1, 'SGEBRD', ' ', M, N, + $ -1, -1 ) + IF( WNTUS .OR. WNTUO ) + $ MAXWRK = MAX( MAXWRK, 3*N+N* + $ ILAENV( 1, 'SORGBR', 'Q', M, N, N, -1 ) ) + IF( WNTUA ) + $ MAXWRK = MAX( MAXWRK, 3*N+M* + $ ILAENV( 1, 'SORGBR', 'Q', M, M, N, -1 ) ) + IF( .NOT.WNTVN ) + $ MAXWRK = MAX( MAXWRK, 3*N+( N-1 )* + $ ILAENV( 1, 'SORGBR', 'P', N, N, N, -1 ) ) + 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 + IF( N.GE.MNTHR ) THEN + IF( WNTVN ) THEN +* +* Path 1t(N much larger than M, JOBVT='N') +* + MAXWRK = M + M*ILAENV( 1, 'SGELQF', ' ', M, N, -1, + $ -1 ) + MAXWRK = MAX( MAXWRK, 3*M+2*M* + $ ILAENV( 1, 'SGEBRD', ' ', M, M, -1, -1 ) ) + IF( WNTUO .OR. WNTUAS ) + $ MAXWRK = MAX( MAXWRK, 3*M+M* + $ ILAENV( 1, 'SORGBR', 'Q', M, M, M, -1 ) ) + 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 + M*ILAENV( 1, 'SGELQF', ' ', M, N, -1, -1 ) + WRKBL = MAX( WRKBL, M+M*ILAENV( 1, 'SORGLQ', ' ', M, + $ N, M, -1 ) ) + WRKBL = MAX( WRKBL, 3*M+2*M* + $ ILAENV( 1, 'SGEBRD', ' ', M, M, -1, -1 ) ) + WRKBL = MAX( WRKBL, 3*M+( M-1 )* + $ ILAENV( 1, 'SORGBR', 'P', M, M, M, -1 ) ) + 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 + M*ILAENV( 1, 'SGELQF', ' ', M, N, -1, -1 ) + WRKBL = MAX( WRKBL, M+M*ILAENV( 1, 'SORGLQ', ' ', M, + $ N, M, -1 ) ) + WRKBL = MAX( WRKBL, 3*M+2*M* + $ ILAENV( 1, 'SGEBRD', ' ', M, M, -1, -1 ) ) + WRKBL = MAX( WRKBL, 3*M+( M-1 )* + $ ILAENV( 1, 'SORGBR', 'P', M, M, M, -1 ) ) + WRKBL = MAX( WRKBL, 3*M+M* + $ ILAENV( 1, 'SORGBR', 'Q', M, M, M, -1 ) ) + 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 + M*ILAENV( 1, 'SGELQF', ' ', M, N, -1, -1 ) + WRKBL = MAX( WRKBL, M+M*ILAENV( 1, 'SORGLQ', ' ', M, + $ N, M, -1 ) ) + WRKBL = MAX( WRKBL, 3*M+2*M* + $ ILAENV( 1, 'SGEBRD', ' ', M, M, -1, -1 ) ) + WRKBL = MAX( WRKBL, 3*M+( M-1 )* + $ ILAENV( 1, 'SORGBR', 'P', M, M, M, -1 ) ) + 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 + M*ILAENV( 1, 'SGELQF', ' ', M, N, -1, -1 ) + WRKBL = MAX( WRKBL, M+M*ILAENV( 1, 'SORGLQ', ' ', M, + $ N, M, -1 ) ) + WRKBL = MAX( WRKBL, 3*M+2*M* + $ ILAENV( 1, 'SGEBRD', ' ', M, M, -1, -1 ) ) + WRKBL = MAX( WRKBL, 3*M+( M-1 )* + $ ILAENV( 1, 'SORGBR', 'P', M, M, M, -1 ) ) + WRKBL = MAX( WRKBL, 3*M+M* + $ ILAENV( 1, 'SORGBR', 'Q', M, M, M, -1 ) ) + 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 + M*ILAENV( 1, 'SGELQF', ' ', M, N, -1, -1 ) + WRKBL = MAX( WRKBL, M+M*ILAENV( 1, 'SORGLQ', ' ', M, + $ N, M, -1 ) ) + WRKBL = MAX( WRKBL, 3*M+2*M* + $ ILAENV( 1, 'SGEBRD', ' ', M, M, -1, -1 ) ) + WRKBL = MAX( WRKBL, 3*M+( M-1 )* + $ ILAENV( 1, 'SORGBR', 'P', M, M, M, -1 ) ) + WRKBL = MAX( WRKBL, 3*M+M* + $ ILAENV( 1, 'SORGBR', 'Q', M, M, M, -1 ) ) + 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 + M*ILAENV( 1, 'SGELQF', ' ', M, N, -1, -1 ) + WRKBL = MAX( WRKBL, M+N*ILAENV( 1, 'SORGLQ', ' ', N, + $ N, M, -1 ) ) + WRKBL = MAX( WRKBL, 3*M+2*M* + $ ILAENV( 1, 'SGEBRD', ' ', M, M, -1, -1 ) ) + WRKBL = MAX( WRKBL, 3*M+( M-1 )* + $ ILAENV( 1, 'SORGBR', 'P', M, M, M, -1 ) ) + 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 + M*ILAENV( 1, 'SGELQF', ' ', M, N, -1, -1 ) + WRKBL = MAX( WRKBL, M+N*ILAENV( 1, 'SORGLQ', ' ', N, + $ N, M, -1 ) ) + WRKBL = MAX( WRKBL, 3*M+2*M* + $ ILAENV( 1, 'SGEBRD', ' ', M, M, -1, -1 ) ) + WRKBL = MAX( WRKBL, 3*M+( M-1 )* + $ ILAENV( 1, 'SORGBR', 'P', M, M, M, -1 ) ) + WRKBL = MAX( WRKBL, 3*M+M* + $ ILAENV( 1, 'SORGBR', 'Q', M, M, M, -1 ) ) + 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 + M*ILAENV( 1, 'SGELQF', ' ', M, N, -1, -1 ) + WRKBL = MAX( WRKBL, M+N*ILAENV( 1, 'SORGLQ', ' ', N, + $ N, M, -1 ) ) + WRKBL = MAX( WRKBL, 3*M+2*M* + $ ILAENV( 1, 'SGEBRD', ' ', M, M, -1, -1 ) ) + WRKBL = MAX( WRKBL, 3*M+( M-1 )* + $ ILAENV( 1, 'SORGBR', 'P', M, M, M, -1 ) ) + WRKBL = MAX( WRKBL, 3*M+M* + $ ILAENV( 1, 'SORGBR', 'Q', M, M, M, -1 ) ) + 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) +* + MAXWRK = 3*M + ( M+N )*ILAENV( 1, 'SGEBRD', ' ', M, N, + $ -1, -1 ) + IF( WNTVS .OR. WNTVO ) + $ MAXWRK = MAX( MAXWRK, 3*M+M* + $ ILAENV( 1, 'SORGBR', 'P', M, N, M, -1 ) ) + IF( WNTVA ) + $ MAXWRK = MAX( MAXWRK, 3*M+N* + $ ILAENV( 1, 'SORGBR', 'P', N, N, M, -1 ) ) + IF( .NOT.WNTUN ) + $ MAXWRK = MAX( MAXWRK, 3*M+( M-1 )* + $ ILAENV( 1, 'SORGBR', 'Q', M, M, M, -1 ) ) + MAXWRK = MAX( MAXWRK, BDSPAC ) + MINWRK = MAX( 3*M+N, BDSPAC ) + END IF + END IF + MAXWRK = MAX( MAXWRK, MINWRK ) + WORK( 1 ) = 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 +* + CALL SLASET( 'L', N-1, N-1, ZERO, ZERO, A( 2, 1 ), LDA ) + 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 +* + CALL SLASET( 'L', N-1, N-1, ZERO, ZERO, A( 2, 1 ), + $ LDA ) +* +* 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 +* + CALL SLASET( 'L', N-1, N-1, ZERO, ZERO, A( 2, 1 ), + $ LDA ) +* +* 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 +* + CALL SLASET( 'L', N-1, N-1, ZERO, ZERO, A( 2, 1 ), + $ LDA ) +* +* 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 +* + CALL SLASET( 'L', N-1, N-1, ZERO, ZERO, A( 2, 1 ), + $ LDA ) +* +* 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 ) = MAXWRK +* + RETURN +* +* End of SGESVD +* + END |