 LAPACK  3.8.0 LAPACK: Linear Algebra PACKage

## ◆ cggesx()

 subroutine cggesx ( character JOBVSL, character JOBVSR, character SORT, external SELCTG, character SENSE, integer N, complex, dimension( lda, * ) A, integer LDA, complex, dimension( ldb, * ) B, integer LDB, integer SDIM, complex, dimension( * ) ALPHA, complex, dimension( * ) BETA, complex, dimension( ldvsl, * ) VSL, integer LDVSL, complex, dimension( ldvsr, * ) VSR, integer LDVSR, real, dimension( 2 ) RCONDE, real, dimension( 2 ) RCONDV, complex, dimension( * ) WORK, integer LWORK, real, dimension( * ) RWORK, integer, dimension( * ) IWORK, integer LIWORK, logical, dimension( * ) BWORK, integer INFO )

CGGESX computes the eigenvalues, the Schur form, and, optionally, the matrix of Schur vectors for GE matrices

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Purpose:
``` CGGESX computes for a pair of N-by-N complex nonsymmetric matrices
(A,B), the generalized eigenvalues, the complex Schur form (S,T),
and, optionally, the left and/or right matrices of Schur vectors (VSL
and VSR).  This gives the generalized Schur factorization

(A,B) = ( (VSL) S (VSR)**H, (VSL) T (VSR)**H )

where (VSR)**H is the conjugate-transpose of VSR.

Optionally, it also orders the eigenvalues so that a selected cluster
of eigenvalues appears in the leading diagonal blocks of the upper
triangular matrix S and the upper triangular matrix T; computes
a reciprocal condition number for the average of the selected
eigenvalues (RCONDE); and computes a reciprocal condition number for
the right and left deflating subspaces corresponding to the selected
eigenvalues (RCONDV). The leading columns of VSL and VSR then form
an orthonormal basis for the corresponding left and right eigenspaces
(deflating subspaces).

A generalized eigenvalue for a pair of matrices (A,B) is a scalar w
or a ratio alpha/beta = w, such that  A - w*B is singular.  It is
usually represented as the pair (alpha,beta), as there is a
reasonable interpretation for beta=0 or for both being zero.

A pair of matrices (S,T) is in generalized complex Schur form if T is
upper triangular with non-negative diagonal and S is upper
triangular.```
Parameters
 [in] JOBVSL ``` JOBVSL is CHARACTER*1 = 'N': do not compute the left Schur vectors; = 'V': compute the left Schur vectors.``` [in] JOBVSR ``` JOBVSR is CHARACTER*1 = 'N': do not compute the right Schur vectors; = 'V': compute the right Schur vectors.``` [in] SORT ``` SORT is CHARACTER*1 Specifies whether or not to order the eigenvalues on the diagonal of the generalized Schur form. = 'N': Eigenvalues are not ordered; = 'S': Eigenvalues are ordered (see SELCTG).``` [in] SELCTG ``` SELCTG is a LOGICAL FUNCTION of two COMPLEX arguments SELCTG must be declared EXTERNAL in the calling subroutine. If SORT = 'N', SELCTG is not referenced. If SORT = 'S', SELCTG is used to select eigenvalues to sort to the top left of the Schur form. Note that a selected complex eigenvalue may no longer satisfy SELCTG(ALPHA(j),BETA(j)) = .TRUE. after ordering, since ordering may change the value of complex eigenvalues (especially if the eigenvalue is ill-conditioned), in this case INFO is set to N+3 see INFO below).``` [in] SENSE ``` SENSE is CHARACTER*1 Determines which reciprocal condition numbers are computed. = 'N' : None are computed; = 'E' : Computed for average of selected eigenvalues only; = 'V' : Computed for selected deflating subspaces only; = 'B' : Computed for both. If SENSE = 'E', 'V', or 'B', SORT must equal 'S'.``` [in] N ``` N is INTEGER The order of the matrices A, B, VSL, and VSR. N >= 0.``` [in,out] A ``` A is COMPLEX array, dimension (LDA, N) On entry, the first of the pair of matrices. On exit, A has been overwritten by its generalized Schur form S.``` [in] LDA ``` LDA is INTEGER The leading dimension of A. LDA >= max(1,N).``` [in,out] B ``` B is COMPLEX array, dimension (LDB, N) On entry, the second of the pair of matrices. On exit, B has been overwritten by its generalized Schur form T.``` [in] LDB ``` LDB is INTEGER The leading dimension of B. LDB >= max(1,N).``` [out] SDIM ``` SDIM is INTEGER If SORT = 'N', SDIM = 0. If SORT = 'S', SDIM = number of eigenvalues (after sorting) for which SELCTG is true.``` [out] ALPHA ` ALPHA is COMPLEX array, dimension (N)` [out] BETA ``` BETA is COMPLEX array, dimension (N) On exit, ALPHA(j)/BETA(j), j=1,...,N, will be the generalized eigenvalues. ALPHA(j) and BETA(j),j=1,...,N are the diagonals of the complex Schur form (S,T). BETA(j) will be non-negative real. Note: the quotients ALPHA(j)/BETA(j) may easily over- or underflow, and BETA(j) may even be zero. Thus, the user should avoid naively computing the ratio alpha/beta. However, ALPHA will be always less than and usually comparable with norm(A) in magnitude, and BETA always less than and usually comparable with norm(B).``` [out] VSL ``` VSL is COMPLEX array, dimension (LDVSL,N) If JOBVSL = 'V', VSL will contain the left Schur vectors. Not referenced if JOBVSL = 'N'.``` [in] LDVSL ``` LDVSL is INTEGER The leading dimension of the matrix VSL. LDVSL >=1, and if JOBVSL = 'V', LDVSL >= N.``` [out] VSR ``` VSR is COMPLEX array, dimension (LDVSR,N) If JOBVSR = 'V', VSR will contain the right Schur vectors. Not referenced if JOBVSR = 'N'.``` [in] LDVSR ``` LDVSR is INTEGER The leading dimension of the matrix VSR. LDVSR >= 1, and if JOBVSR = 'V', LDVSR >= N.``` [out] RCONDE ``` RCONDE is REAL array, dimension ( 2 ) If SENSE = 'E' or 'B', RCONDE(1) and RCONDE(2) contain the reciprocal condition numbers for the average of the selected eigenvalues. Not referenced if SENSE = 'N' or 'V'.``` [out] RCONDV ``` RCONDV is REAL array, dimension ( 2 ) If SENSE = 'V' or 'B', RCONDV(1) and RCONDV(2) contain the reciprocal condition number for the selected deflating subspaces. Not referenced if SENSE = 'N' or 'E'.``` [out] WORK ``` WORK is COMPLEX array, dimension (MAX(1,LWORK)) On exit, if INFO = 0, WORK(1) returns the optimal LWORK.``` [in] LWORK ``` LWORK is INTEGER The dimension of the array WORK. If N = 0, LWORK >= 1, else if SENSE = 'E', 'V', or 'B', LWORK >= MAX(1,2*N,2*SDIM*(N-SDIM)), else LWORK >= MAX(1,2*N). Note that 2*SDIM*(N-SDIM) <= N*N/2. Note also that an error is only returned if LWORK < MAX(1,2*N), but if SENSE = 'E' or 'V' or 'B' this may not be large enough. If LWORK = -1, then a workspace query is assumed; the routine only calculates the bound on the optimal size of the WORK array and the minimum size of the IWORK array, returns these values as the first entries of the WORK and IWORK arrays, and no error message related to LWORK or LIWORK is issued by XERBLA.``` [out] RWORK ``` RWORK is REAL array, dimension ( 8*N ) Real workspace.``` [out] IWORK ``` IWORK is INTEGER array, dimension (MAX(1,LIWORK)) On exit, if INFO = 0, IWORK(1) returns the minimum LIWORK.``` [in] LIWORK ``` LIWORK is INTEGER The dimension of the array WORK. If SENSE = 'N' or N = 0, LIWORK >= 1, otherwise LIWORK >= N+2. If LIWORK = -1, then a workspace query is assumed; the routine only calculates the bound on the optimal size of the WORK array and the minimum size of the IWORK array, returns these values as the first entries of the WORK and IWORK arrays, and no error message related to LWORK or LIWORK is issued by XERBLA.``` [out] BWORK ``` BWORK is LOGICAL array, dimension (N) Not referenced if SORT = 'N'.``` [out] INFO ``` INFO is INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value. = 1,...,N: The QZ iteration failed. (A,B) are not in Schur form, but ALPHA(j) and BETA(j) should be correct for j=INFO+1,...,N. > N: =N+1: other than QZ iteration failed in CHGEQZ =N+2: after reordering, roundoff changed values of some complex eigenvalues so that leading eigenvalues in the Generalized Schur form no longer satisfy SELCTG=.TRUE. This could also be caused due to scaling. =N+3: reordering failed in CTGSEN.```
Date
June 2017

Definition at line 332 of file cggesx.f.

332 *
333 * -- LAPACK driver routine (version 3.7.1) --
334 * -- LAPACK is a software package provided by Univ. of Tennessee, --
335 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
336 * June 2017
337 *
338 * .. Scalar Arguments ..
339  CHARACTER jobvsl, jobvsr, sense, sort
340  INTEGER info, lda, ldb, ldvsl, ldvsr, liwork, lwork, n,
341  \$ sdim
342 * ..
343 * .. Array Arguments ..
344  LOGICAL bwork( * )
345  INTEGER iwork( * )
346  REAL rconde( 2 ), rcondv( 2 ), rwork( * )
347  COMPLEX a( lda, * ), alpha( * ), b( ldb, * ),
348  \$ beta( * ), vsl( ldvsl, * ), vsr( ldvsr, * ),
349  \$ work( * )
350 * ..
351 * .. Function Arguments ..
352  LOGICAL selctg
353  EXTERNAL selctg
354 * ..
355 *
356 * =====================================================================
357 *
358 * .. Parameters ..
359  REAL zero, one
360  parameter( zero = 0.0e+0, one = 1.0e+0 )
361  COMPLEX czero, cone
362  parameter( czero = ( 0.0e+0, 0.0e+0 ),
363  \$ cone = ( 1.0e+0, 0.0e+0 ) )
364 * ..
365 * .. Local Scalars ..
366  LOGICAL cursl, ilascl, ilbscl, ilvsl, ilvsr, lastsl,
367  \$ lquery, wantsb, wantse, wantsn, wantst, wantsv
368  INTEGER i, icols, ierr, ihi, ijob, ijobvl, ijobvr,
369  \$ ileft, ilo, iright, irows, irwrk, itau, iwrk,
370  \$ liwmin, lwrk, maxwrk, minwrk
371  REAL anrm, anrmto, bignum, bnrm, bnrmto, eps, pl,
372  \$ pr, smlnum
373 * ..
374 * .. Local Arrays ..
375  REAL dif( 2 )
376 * ..
377 * .. External Subroutines ..
378  EXTERNAL cgeqrf, cggbak, cggbal, cgghrd, chgeqz, clacpy,
380  \$ xerbla
381 * ..
382 * .. External Functions ..
383  LOGICAL lsame
384  INTEGER ilaenv
385  REAL clange, slamch
386  EXTERNAL lsame, ilaenv, clange, slamch
387 * ..
388 * .. Intrinsic Functions ..
389  INTRINSIC max, sqrt
390 * ..
391 * .. Executable Statements ..
392 *
393 * Decode the input arguments
394 *
395  IF( lsame( jobvsl, 'N' ) ) THEN
396  ijobvl = 1
397  ilvsl = .false.
398  ELSE IF( lsame( jobvsl, 'V' ) ) THEN
399  ijobvl = 2
400  ilvsl = .true.
401  ELSE
402  ijobvl = -1
403  ilvsl = .false.
404  END IF
405 *
406  IF( lsame( jobvsr, 'N' ) ) THEN
407  ijobvr = 1
408  ilvsr = .false.
409  ELSE IF( lsame( jobvsr, 'V' ) ) THEN
410  ijobvr = 2
411  ilvsr = .true.
412  ELSE
413  ijobvr = -1
414  ilvsr = .false.
415  END IF
416 *
417  wantst = lsame( sort, 'S' )
418  wantsn = lsame( sense, 'N' )
419  wantse = lsame( sense, 'E' )
420  wantsv = lsame( sense, 'V' )
421  wantsb = lsame( sense, 'B' )
422  lquery = ( lwork.EQ.-1 .OR. liwork.EQ.-1 )
423  IF( wantsn ) THEN
424  ijob = 0
425  ELSE IF( wantse ) THEN
426  ijob = 1
427  ELSE IF( wantsv ) THEN
428  ijob = 2
429  ELSE IF( wantsb ) THEN
430  ijob = 4
431  END IF
432 *
433 * Test the input arguments
434 *
435  info = 0
436  IF( ijobvl.LE.0 ) THEN
437  info = -1
438  ELSE IF( ijobvr.LE.0 ) THEN
439  info = -2
440  ELSE IF( ( .NOT.wantst ) .AND. ( .NOT.lsame( sort, 'N' ) ) ) THEN
441  info = -3
442  ELSE IF( .NOT.( wantsn .OR. wantse .OR. wantsv .OR. wantsb ) .OR.
443  \$ ( .NOT.wantst .AND. .NOT.wantsn ) ) THEN
444  info = -5
445  ELSE IF( n.LT.0 ) THEN
446  info = -6
447  ELSE IF( lda.LT.max( 1, n ) ) THEN
448  info = -8
449  ELSE IF( ldb.LT.max( 1, n ) ) THEN
450  info = -10
451  ELSE IF( ldvsl.LT.1 .OR. ( ilvsl .AND. ldvsl.LT.n ) ) THEN
452  info = -15
453  ELSE IF( ldvsr.LT.1 .OR. ( ilvsr .AND. ldvsr.LT.n ) ) THEN
454  info = -17
455  END IF
456 *
457 * Compute workspace
458 * (Note: Comments in the code beginning "Workspace:" describe the
459 * minimal amount of workspace needed at that point in the code,
460 * as well as the preferred amount for good performance.
461 * NB refers to the optimal block size for the immediately
462 * following subroutine, as returned by ILAENV.)
463 *
464  IF( info.EQ.0 ) THEN
465  IF( n.GT.0) THEN
466  minwrk = 2*n
467  maxwrk = n*(1 + ilaenv( 1, 'CGEQRF', ' ', n, 1, n, 0 ) )
468  maxwrk = max( maxwrk, n*( 1 +
469  \$ ilaenv( 1, 'CUNMQR', ' ', n, 1, n, -1 ) ) )
470  IF( ilvsl ) THEN
471  maxwrk = max( maxwrk, n*( 1 +
472  \$ ilaenv( 1, 'CUNGQR', ' ', n, 1, n, -1 ) ) )
473  END IF
474  lwrk = maxwrk
475  IF( ijob.GE.1 )
476  \$ lwrk = max( lwrk, n*n/2 )
477  ELSE
478  minwrk = 1
479  maxwrk = 1
480  lwrk = 1
481  END IF
482  work( 1 ) = lwrk
483  IF( wantsn .OR. n.EQ.0 ) THEN
484  liwmin = 1
485  ELSE
486  liwmin = n + 2
487  END IF
488  iwork( 1 ) = liwmin
489 *
490  IF( lwork.LT.minwrk .AND. .NOT.lquery ) THEN
491  info = -21
492  ELSE IF( liwork.LT.liwmin .AND. .NOT.lquery) THEN
493  info = -24
494  END IF
495  END IF
496 *
497  IF( info.NE.0 ) THEN
498  CALL xerbla( 'CGGESX', -info )
499  RETURN
500  ELSE IF (lquery) THEN
501  RETURN
502  END IF
503 *
504 * Quick return if possible
505 *
506  IF( n.EQ.0 ) THEN
507  sdim = 0
508  RETURN
509  END IF
510 *
511 * Get machine constants
512 *
513  eps = slamch( 'P' )
514  smlnum = slamch( 'S' )
515  bignum = one / smlnum
516  CALL slabad( smlnum, bignum )
517  smlnum = sqrt( smlnum ) / eps
518  bignum = one / smlnum
519 *
520 * Scale A if max element outside range [SMLNUM,BIGNUM]
521 *
522  anrm = clange( 'M', n, n, a, lda, rwork )
523  ilascl = .false.
524  IF( anrm.GT.zero .AND. anrm.LT.smlnum ) THEN
525  anrmto = smlnum
526  ilascl = .true.
527  ELSE IF( anrm.GT.bignum ) THEN
528  anrmto = bignum
529  ilascl = .true.
530  END IF
531  IF( ilascl )
532  \$ CALL clascl( 'G', 0, 0, anrm, anrmto, n, n, a, lda, ierr )
533 *
534 * Scale B if max element outside range [SMLNUM,BIGNUM]
535 *
536  bnrm = clange( 'M', n, n, b, ldb, rwork )
537  ilbscl = .false.
538  IF( bnrm.GT.zero .AND. bnrm.LT.smlnum ) THEN
539  bnrmto = smlnum
540  ilbscl = .true.
541  ELSE IF( bnrm.GT.bignum ) THEN
542  bnrmto = bignum
543  ilbscl = .true.
544  END IF
545  IF( ilbscl )
546  \$ CALL clascl( 'G', 0, 0, bnrm, bnrmto, n, n, b, ldb, ierr )
547 *
548 * Permute the matrix to make it more nearly triangular
549 * (Real Workspace: need 6*N)
550 *
551  ileft = 1
552  iright = n + 1
553  irwrk = iright + n
554  CALL cggbal( 'P', n, a, lda, b, ldb, ilo, ihi, rwork( ileft ),
555  \$ rwork( iright ), rwork( irwrk ), ierr )
556 *
557 * Reduce B to triangular form (QR decomposition of B)
558 * (Complex Workspace: need N, prefer N*NB)
559 *
560  irows = ihi + 1 - ilo
561  icols = n + 1 - ilo
562  itau = 1
563  iwrk = itau + irows
564  CALL cgeqrf( irows, icols, b( ilo, ilo ), ldb, work( itau ),
565  \$ work( iwrk ), lwork+1-iwrk, ierr )
566 *
567 * Apply the unitary transformation to matrix A
568 * (Complex Workspace: need N, prefer N*NB)
569 *
570  CALL cunmqr( 'L', 'C', irows, icols, irows, b( ilo, ilo ), ldb,
571  \$ work( itau ), a( ilo, ilo ), lda, work( iwrk ),
572  \$ lwork+1-iwrk, ierr )
573 *
574 * Initialize VSL
575 * (Complex Workspace: need N, prefer N*NB)
576 *
577  IF( ilvsl ) THEN
578  CALL claset( 'Full', n, n, czero, cone, vsl, ldvsl )
579  IF( irows.GT.1 ) THEN
580  CALL clacpy( 'L', irows-1, irows-1, b( ilo+1, ilo ), ldb,
581  \$ vsl( ilo+1, ilo ), ldvsl )
582  END IF
583  CALL cungqr( irows, irows, irows, vsl( ilo, ilo ), ldvsl,
584  \$ work( itau ), work( iwrk ), lwork+1-iwrk, ierr )
585  END IF
586 *
587 * Initialize VSR
588 *
589  IF( ilvsr )
590  \$ CALL claset( 'Full', n, n, czero, cone, vsr, ldvsr )
591 *
592 * Reduce to generalized Hessenberg form
593 * (Workspace: none needed)
594 *
595  CALL cgghrd( jobvsl, jobvsr, n, ilo, ihi, a, lda, b, ldb, vsl,
596  \$ ldvsl, vsr, ldvsr, ierr )
597 *
598  sdim = 0
599 *
600 * Perform QZ algorithm, computing Schur vectors if desired
601 * (Complex Workspace: need N)
602 * (Real Workspace: need N)
603 *
604  iwrk = itau
605  CALL chgeqz( 'S', jobvsl, jobvsr, n, ilo, ihi, a, lda, b, ldb,
606  \$ alpha, beta, vsl, ldvsl, vsr, ldvsr, work( iwrk ),
607  \$ lwork+1-iwrk, rwork( irwrk ), ierr )
608  IF( ierr.NE.0 ) THEN
609  IF( ierr.GT.0 .AND. ierr.LE.n ) THEN
610  info = ierr
611  ELSE IF( ierr.GT.n .AND. ierr.LE.2*n ) THEN
612  info = ierr - n
613  ELSE
614  info = n + 1
615  END IF
616  GO TO 40
617  END IF
618 *
619 * Sort eigenvalues ALPHA/BETA and compute the reciprocal of
620 * condition number(s)
621 *
622  IF( wantst ) THEN
623 *
624 * Undo scaling on eigenvalues before SELCTGing
625 *
626  IF( ilascl )
627  \$ CALL clascl( 'G', 0, 0, anrmto, anrm, n, 1, alpha, n, ierr )
628  IF( ilbscl )
629  \$ CALL clascl( 'G', 0, 0, bnrmto, bnrm, n, 1, beta, n, ierr )
630 *
631 * Select eigenvalues
632 *
633  DO 10 i = 1, n
634  bwork( i ) = selctg( alpha( i ), beta( i ) )
635  10 CONTINUE
636 *
637 * Reorder eigenvalues, transform Generalized Schur vectors, and
638 * compute reciprocal condition numbers
639 * (Complex Workspace: If IJOB >= 1, need MAX(1, 2*SDIM*(N-SDIM))
640 * otherwise, need 1 )
641 *
642  CALL ctgsen( ijob, ilvsl, ilvsr, bwork, n, a, lda, b, ldb,
643  \$ alpha, beta, vsl, ldvsl, vsr, ldvsr, sdim, pl, pr,
644  \$ dif, work( iwrk ), lwork-iwrk+1, iwork, liwork,
645  \$ ierr )
646 *
647  IF( ijob.GE.1 )
648  \$ maxwrk = max( maxwrk, 2*sdim*( n-sdim ) )
649  IF( ierr.EQ.-21 ) THEN
650 *
651 * not enough complex workspace
652 *
653  info = -21
654  ELSE
655  IF( ijob.EQ.1 .OR. ijob.EQ.4 ) THEN
656  rconde( 1 ) = pl
657  rconde( 2 ) = pr
658  END IF
659  IF( ijob.EQ.2 .OR. ijob.EQ.4 ) THEN
660  rcondv( 1 ) = dif( 1 )
661  rcondv( 2 ) = dif( 2 )
662  END IF
663  IF( ierr.EQ.1 )
664  \$ info = n + 3
665  END IF
666 *
667  END IF
668 *
669 * Apply permutation to VSL and VSR
670 * (Workspace: none needed)
671 *
672  IF( ilvsl )
673  \$ CALL cggbak( 'P', 'L', n, ilo, ihi, rwork( ileft ),
674  \$ rwork( iright ), n, vsl, ldvsl, ierr )
675 *
676  IF( ilvsr )
677  \$ CALL cggbak( 'P', 'R', n, ilo, ihi, rwork( ileft ),
678  \$ rwork( iright ), n, vsr, ldvsr, ierr )
679 *
680 * Undo scaling
681 *
682  IF( ilascl ) THEN
683  CALL clascl( 'U', 0, 0, anrmto, anrm, n, n, a, lda, ierr )
684  CALL clascl( 'G', 0, 0, anrmto, anrm, n, 1, alpha, n, ierr )
685  END IF
686 *
687  IF( ilbscl ) THEN
688  CALL clascl( 'U', 0, 0, bnrmto, bnrm, n, n, b, ldb, ierr )
689  CALL clascl( 'G', 0, 0, bnrmto, bnrm, n, 1, beta, n, ierr )
690  END IF
691 *
692  IF( wantst ) THEN
693 *
694 * Check if reordering is correct
695 *
696  lastsl = .true.
697  sdim = 0
698  DO 30 i = 1, n
699  cursl = selctg( alpha( i ), beta( i ) )
700  IF( cursl )
701  \$ sdim = sdim + 1
702  IF( cursl .AND. .NOT.lastsl )
703  \$ info = n + 2
704  lastsl = cursl
705  30 CONTINUE
706 *
707  END IF
708 *
709  40 CONTINUE
710 *
711  work( 1 ) = maxwrk
712  iwork( 1 ) = liwmin
713 *
714  RETURN
715 *
716 * End of CGGESX
717 *
subroutine cggbal(JOB, N, A, LDA, B, LDB, ILO, IHI, LSCALE, RSCALE, WORK, INFO)
CGGBAL
Definition: cggbal.f:179
subroutine claset(UPLO, M, N, ALPHA, BETA, A, LDA)
CLASET initializes the off-diagonal elements and the diagonal elements of a matrix to given values...
Definition: claset.f:108
subroutine cungqr(M, N, K, A, LDA, TAU, WORK, LWORK, INFO)
CUNGQR
Definition: cungqr.f:130
subroutine clascl(TYPE, KL, KU, CFROM, CTO, M, N, A, LDA, INFO)
CLASCL multiplies a general rectangular matrix by a real scalar defined as cto/cfrom.
Definition: clascl.f:145
subroutine chgeqz(JOB, COMPQ, COMPZ, N, ILO, IHI, H, LDH, T, LDT, ALPHA, BETA, Q, LDQ, Z, LDZ, WORK, LWORK, RWORK, INFO)
CHGEQZ
Definition: chgeqz.f:286
integer function ilaenv(ISPEC, NAME, OPTS, N1, N2, N3, N4)
ILAENV
Definition: tstiee.f:83
real function clange(NORM, M, N, A, LDA, WORK)
CLANGE returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value ...
Definition: clange.f:117
subroutine xerbla(SRNAME, INFO)
XERBLA
Definition: xerbla.f:62
subroutine cgeqrf(M, N, A, LDA, TAU, WORK, LWORK, INFO)
CGEQRF
Definition: cgeqrf.f:138
subroutine ctgsen(IJOB, WANTQ, WANTZ, SELECT, N, A, LDA, B, LDB, ALPHA, BETA, Q, LDQ, Z, LDZ, M, PL, PR, DIF, WORK, LWORK, IWORK, LIWORK, INFO)
CTGSEN
Definition: ctgsen.f:435
logical function lsame(CA, CB)
LSAME
Definition: lsame.f:55
real function slamch(CMACH)
SLAMCH
Definition: slamch.f:69
subroutine clacpy(UPLO, M, N, A, LDA, B, LDB)
CLACPY copies all or part of one two-dimensional array to another.
Definition: clacpy.f:105
subroutine slabad(SMALL, LARGE)
SLABAD
Definition: slabad.f:76
subroutine cgghrd(COMPQ, COMPZ, N, ILO, IHI, A, LDA, B, LDB, Q, LDQ, Z, LDZ, INFO)
CGGHRD
Definition: cgghrd.f:206
subroutine cggbak(JOB, SIDE, N, ILO, IHI, LSCALE, RSCALE, M, V, LDV, INFO)
CGGBAK
Definition: cggbak.f:150
subroutine cunmqr(SIDE, TRANS, M, N, K, A, LDA, TAU, C, LDC, WORK, LWORK, INFO)
CUNMQR
Definition: cunmqr.f:170
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