Annotation of rpl/lapack/lapack/zgeevx.f, revision 1.3

1.1       bertrand    1:       SUBROUTINE ZGEEVX( BALANC, JOBVL, JOBVR, SENSE, N, A, LDA, W, VL,
                      2:      $                   LDVL, VR, LDVR, ILO, IHI, SCALE, ABNRM, RCONDE,
                      3:      $                   RCONDV, WORK, LWORK, RWORK, INFO )
                      4: *
                      5: *  -- LAPACK driver routine (version 3.2) --
                      6: *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
                      7: *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
                      8: *     November 2006
                      9: *
                     10: *     .. Scalar Arguments ..
                     11:       CHARACTER          BALANC, JOBVL, JOBVR, SENSE
                     12:       INTEGER            IHI, ILO, INFO, LDA, LDVL, LDVR, LWORK, N
                     13:       DOUBLE PRECISION   ABNRM
                     14: *     ..
                     15: *     .. Array Arguments ..
                     16:       DOUBLE PRECISION   RCONDE( * ), RCONDV( * ), RWORK( * ),
                     17:      $                   SCALE( * )
                     18:       COMPLEX*16         A( LDA, * ), VL( LDVL, * ), VR( LDVR, * ),
                     19:      $                   W( * ), WORK( * )
                     20: *     ..
                     21: *
                     22: *  Purpose
                     23: *  =======
                     24: *
                     25: *  ZGEEVX computes for an N-by-N complex nonsymmetric matrix A, the
                     26: *  eigenvalues and, optionally, the left and/or right eigenvectors.
                     27: *
                     28: *  Optionally also, it computes a balancing transformation to improve
                     29: *  the conditioning of the eigenvalues and eigenvectors (ILO, IHI,
                     30: *  SCALE, and ABNRM), reciprocal condition numbers for the eigenvalues
                     31: *  (RCONDE), and reciprocal condition numbers for the right
                     32: *  eigenvectors (RCONDV).
                     33: *
                     34: *  The right eigenvector v(j) of A satisfies
                     35: *                   A * v(j) = lambda(j) * v(j)
                     36: *  where lambda(j) is its eigenvalue.
                     37: *  The left eigenvector u(j) of A satisfies
                     38: *                u(j)**H * A = lambda(j) * u(j)**H
                     39: *  where u(j)**H denotes the conjugate transpose of u(j).
                     40: *
                     41: *  The computed eigenvectors are normalized to have Euclidean norm
                     42: *  equal to 1 and largest component real.
                     43: *
                     44: *  Balancing a matrix means permuting the rows and columns to make it
                     45: *  more nearly upper triangular, and applying a diagonal similarity
                     46: *  transformation D * A * D**(-1), where D is a diagonal matrix, to
                     47: *  make its rows and columns closer in norm and the condition numbers
                     48: *  of its eigenvalues and eigenvectors smaller.  The computed
                     49: *  reciprocal condition numbers correspond to the balanced matrix.
                     50: *  Permuting rows and columns will not change the condition numbers
                     51: *  (in exact arithmetic) but diagonal scaling will.  For further
                     52: *  explanation of balancing, see section 4.10.2 of the LAPACK
                     53: *  Users' Guide.
                     54: *
                     55: *  Arguments
                     56: *  =========
                     57: *
                     58: *  BALANC  (input) CHARACTER*1
                     59: *          Indicates how the input matrix should be diagonally scaled
                     60: *          and/or permuted to improve the conditioning of its
                     61: *          eigenvalues.
                     62: *          = 'N': Do not diagonally scale or permute;
                     63: *          = 'P': Perform permutations to make the matrix more nearly
                     64: *                 upper triangular. Do not diagonally scale;
                     65: *          = 'S': Diagonally scale the matrix, ie. replace A by
                     66: *                 D*A*D**(-1), where D is a diagonal matrix chosen
                     67: *                 to make the rows and columns of A more equal in
                     68: *                 norm. Do not permute;
                     69: *          = 'B': Both diagonally scale and permute A.
                     70: *
                     71: *          Computed reciprocal condition numbers will be for the matrix
                     72: *          after balancing and/or permuting. Permuting does not change
                     73: *          condition numbers (in exact arithmetic), but balancing does.
                     74: *
                     75: *  JOBVL   (input) CHARACTER*1
                     76: *          = 'N': left eigenvectors of A are not computed;
                     77: *          = 'V': left eigenvectors of A are computed.
                     78: *          If SENSE = 'E' or 'B', JOBVL must = 'V'.
                     79: *
                     80: *  JOBVR   (input) CHARACTER*1
                     81: *          = 'N': right eigenvectors of A are not computed;
                     82: *          = 'V': right eigenvectors of A are computed.
                     83: *          If SENSE = 'E' or 'B', JOBVR must = 'V'.
                     84: *
                     85: *  SENSE   (input) CHARACTER*1
                     86: *          Determines which reciprocal condition numbers are computed.
                     87: *          = 'N': None are computed;
                     88: *          = 'E': Computed for eigenvalues only;
                     89: *          = 'V': Computed for right eigenvectors only;
                     90: *          = 'B': Computed for eigenvalues and right eigenvectors.
                     91: *
                     92: *          If SENSE = 'E' or 'B', both left and right eigenvectors
                     93: *          must also be computed (JOBVL = 'V' and JOBVR = 'V').
                     94: *
                     95: *  N       (input) INTEGER
                     96: *          The order of the matrix A. N >= 0.
                     97: *
                     98: *  A       (input/output) COMPLEX*16 array, dimension (LDA,N)
                     99: *          On entry, the N-by-N matrix A.
                    100: *          On exit, A has been overwritten.  If JOBVL = 'V' or
                    101: *          JOBVR = 'V', A contains the Schur form of the balanced
                    102: *          version of the matrix A.
                    103: *
                    104: *  LDA     (input) INTEGER
                    105: *          The leading dimension of the array A.  LDA >= max(1,N).
                    106: *
                    107: *  W       (output) COMPLEX*16 array, dimension (N)
                    108: *          W contains the computed eigenvalues.
                    109: *
                    110: *  VL      (output) COMPLEX*16 array, dimension (LDVL,N)
                    111: *          If JOBVL = 'V', the left eigenvectors u(j) are stored one
                    112: *          after another in the columns of VL, in the same order
                    113: *          as their eigenvalues.
                    114: *          If JOBVL = 'N', VL is not referenced.
                    115: *          u(j) = VL(:,j), the j-th column of VL.
                    116: *
                    117: *  LDVL    (input) INTEGER
                    118: *          The leading dimension of the array VL.  LDVL >= 1; if
                    119: *          JOBVL = 'V', LDVL >= N.
                    120: *
                    121: *  VR      (output) COMPLEX*16 array, dimension (LDVR,N)
                    122: *          If JOBVR = 'V', the right eigenvectors v(j) are stored one
                    123: *          after another in the columns of VR, in the same order
                    124: *          as their eigenvalues.
                    125: *          If JOBVR = 'N', VR is not referenced.
                    126: *          v(j) = VR(:,j), the j-th column of VR.
                    127: *
                    128: *  LDVR    (input) INTEGER
                    129: *          The leading dimension of the array VR.  LDVR >= 1; if
                    130: *          JOBVR = 'V', LDVR >= N.
                    131: *
                    132: *  ILO     (output) INTEGER
                    133: *  IHI     (output) INTEGER
                    134: *          ILO and IHI are integer values determined when A was
                    135: *          balanced.  The balanced A(i,j) = 0 if I > J and
                    136: *          J = 1,...,ILO-1 or I = IHI+1,...,N.
                    137: *
                    138: *  SCALE   (output) DOUBLE PRECISION array, dimension (N)
                    139: *          Details of the permutations and scaling factors applied
                    140: *          when balancing A.  If P(j) is the index of the row and column
                    141: *          interchanged with row and column j, and D(j) is the scaling
                    142: *          factor applied to row and column j, then
                    143: *          SCALE(J) = P(J),    for J = 1,...,ILO-1
                    144: *                   = D(J),    for J = ILO,...,IHI
                    145: *                   = P(J)     for J = IHI+1,...,N.
                    146: *          The order in which the interchanges are made is N to IHI+1,
                    147: *          then 1 to ILO-1.
                    148: *
                    149: *  ABNRM   (output) DOUBLE PRECISION
                    150: *          The one-norm of the balanced matrix (the maximum
                    151: *          of the sum of absolute values of elements of any column).
                    152: *
                    153: *  RCONDE  (output) DOUBLE PRECISION array, dimension (N)
                    154: *          RCONDE(j) is the reciprocal condition number of the j-th
                    155: *          eigenvalue.
                    156: *
                    157: *  RCONDV  (output) DOUBLE PRECISION array, dimension (N)
                    158: *          RCONDV(j) is the reciprocal condition number of the j-th
                    159: *          right eigenvector.
                    160: *
                    161: *  WORK    (workspace/output) COMPLEX*16 array, dimension (MAX(1,LWORK))
                    162: *          On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
                    163: *
                    164: *  LWORK   (input) INTEGER
                    165: *          The dimension of the array WORK.  If SENSE = 'N' or 'E',
                    166: *          LWORK >= max(1,2*N), and if SENSE = 'V' or 'B',
                    167: *          LWORK >= N*N+2*N.
                    168: *          For good performance, LWORK must generally be larger.
                    169: *
                    170: *          If LWORK = -1, then a workspace query is assumed; the routine
                    171: *          only calculates the optimal size of the WORK array, returns
                    172: *          this value as the first entry of the WORK array, and no error
                    173: *          message related to LWORK is issued by XERBLA.
                    174: *
                    175: *  RWORK   (workspace) DOUBLE PRECISION array, dimension (2*N)
                    176: *
                    177: *  INFO    (output) INTEGER
                    178: *          = 0:  successful exit
                    179: *          < 0:  if INFO = -i, the i-th argument had an illegal value.
                    180: *          > 0:  if INFO = i, the QR algorithm failed to compute all the
                    181: *                eigenvalues, and no eigenvectors or condition numbers
                    182: *                have been computed; elements 1:ILO-1 and i+1:N of W
                    183: *                contain eigenvalues which have converged.
                    184: *
                    185: *  =====================================================================
                    186: *
                    187: *     .. Parameters ..
                    188:       DOUBLE PRECISION   ZERO, ONE
                    189:       PARAMETER          ( ZERO = 0.0D0, ONE = 1.0D0 )
                    190: *     ..
                    191: *     .. Local Scalars ..
                    192:       LOGICAL            LQUERY, SCALEA, WANTVL, WANTVR, WNTSNB, WNTSNE,
                    193:      $                   WNTSNN, WNTSNV
                    194:       CHARACTER          JOB, SIDE
                    195:       INTEGER            HSWORK, I, ICOND, IERR, ITAU, IWRK, K, MAXWRK,
                    196:      $                   MINWRK, NOUT
                    197:       DOUBLE PRECISION   ANRM, BIGNUM, CSCALE, EPS, SCL, SMLNUM
                    198:       COMPLEX*16         TMP
                    199: *     ..
                    200: *     .. Local Arrays ..
                    201:       LOGICAL            SELECT( 1 )
                    202:       DOUBLE PRECISION   DUM( 1 )
                    203: *     ..
                    204: *     .. External Subroutines ..
                    205:       EXTERNAL           DLABAD, DLASCL, XERBLA, ZDSCAL, ZGEBAK, ZGEBAL,
                    206:      $                   ZGEHRD, ZHSEQR, ZLACPY, ZLASCL, ZSCAL, ZTREVC,
                    207:      $                   ZTRSNA, ZUNGHR
                    208: *     ..
                    209: *     .. External Functions ..
                    210:       LOGICAL            LSAME
                    211:       INTEGER            IDAMAX, ILAENV
                    212:       DOUBLE PRECISION   DLAMCH, DZNRM2, ZLANGE
                    213:       EXTERNAL           LSAME, IDAMAX, ILAENV, DLAMCH, DZNRM2, ZLANGE
                    214: *     ..
                    215: *     .. Intrinsic Functions ..
                    216:       INTRINSIC          DBLE, DCMPLX, DCONJG, DIMAG, MAX, SQRT
                    217: *     ..
                    218: *     .. Executable Statements ..
                    219: *
                    220: *     Test the input arguments
                    221: *
                    222:       INFO = 0
                    223:       LQUERY = ( LWORK.EQ.-1 )
                    224:       WANTVL = LSAME( JOBVL, 'V' )
                    225:       WANTVR = LSAME( JOBVR, 'V' )
                    226:       WNTSNN = LSAME( SENSE, 'N' )
                    227:       WNTSNE = LSAME( SENSE, 'E' )
                    228:       WNTSNV = LSAME( SENSE, 'V' )
                    229:       WNTSNB = LSAME( SENSE, 'B' )
                    230:       IF( .NOT.( LSAME( BALANC, 'N' ) .OR. LSAME( BALANC, 'S' ) .OR.
                    231:      $    LSAME( BALANC, 'P' ) .OR. LSAME( BALANC, 'B' ) ) ) THEN
                    232:          INFO = -1
                    233:       ELSE IF( ( .NOT.WANTVL ) .AND. ( .NOT.LSAME( JOBVL, 'N' ) ) ) THEN
                    234:          INFO = -2
                    235:       ELSE IF( ( .NOT.WANTVR ) .AND. ( .NOT.LSAME( JOBVR, 'N' ) ) ) THEN
                    236:          INFO = -3
                    237:       ELSE IF( .NOT.( WNTSNN .OR. WNTSNE .OR. WNTSNB .OR. WNTSNV ) .OR.
                    238:      $         ( ( WNTSNE .OR. WNTSNB ) .AND. .NOT.( WANTVL .AND.
                    239:      $         WANTVR ) ) ) THEN
                    240:          INFO = -4
                    241:       ELSE IF( N.LT.0 ) THEN
                    242:          INFO = -5
                    243:       ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
                    244:          INFO = -7
                    245:       ELSE IF( LDVL.LT.1 .OR. ( WANTVL .AND. LDVL.LT.N ) ) THEN
                    246:          INFO = -10
                    247:       ELSE IF( LDVR.LT.1 .OR. ( WANTVR .AND. LDVR.LT.N ) ) THEN
                    248:          INFO = -12
                    249:       END IF
                    250: *
                    251: *     Compute workspace
                    252: *      (Note: Comments in the code beginning "Workspace:" describe the
                    253: *       minimal amount of workspace needed at that point in the code,
                    254: *       as well as the preferred amount for good performance.
                    255: *       CWorkspace refers to complex workspace, and RWorkspace to real
                    256: *       workspace. NB refers to the optimal block size for the
                    257: *       immediately following subroutine, as returned by ILAENV.
                    258: *       HSWORK refers to the workspace preferred by ZHSEQR, as
                    259: *       calculated below. HSWORK is computed assuming ILO=1 and IHI=N,
                    260: *       the worst case.)
                    261: *
                    262:       IF( INFO.EQ.0 ) THEN
                    263:          IF( N.EQ.0 ) THEN
                    264:             MINWRK = 1
                    265:             MAXWRK = 1
                    266:          ELSE
                    267:             MAXWRK = N + N*ILAENV( 1, 'ZGEHRD', ' ', N, 1, N, 0 )
                    268: *
                    269:             IF( WANTVL ) THEN
                    270:                CALL ZHSEQR( 'S', 'V', N, 1, N, A, LDA, W, VL, LDVL,
                    271:      $                WORK, -1, INFO )
                    272:             ELSE IF( WANTVR ) THEN
                    273:                CALL ZHSEQR( 'S', 'V', N, 1, N, A, LDA, W, VR, LDVR,
                    274:      $                WORK, -1, INFO )
                    275:             ELSE
                    276:                IF( WNTSNN ) THEN
                    277:                   CALL ZHSEQR( 'E', 'N', N, 1, N, A, LDA, W, VR, LDVR,
                    278:      $                WORK, -1, INFO )
                    279:                ELSE
                    280:                   CALL ZHSEQR( 'S', 'N', N, 1, N, A, LDA, W, VR, LDVR,
                    281:      $                WORK, -1, INFO )
                    282:                END IF
                    283:             END IF
                    284:             HSWORK = WORK( 1 )
                    285: *
                    286:             IF( ( .NOT.WANTVL ) .AND. ( .NOT.WANTVR ) ) THEN
                    287:                MINWRK = 2*N
                    288:                IF( .NOT.( WNTSNN .OR. WNTSNE ) )
                    289:      $            MINWRK = MAX( MINWRK, N*N + 2*N )
                    290:                MAXWRK = MAX( MAXWRK, HSWORK )
                    291:                IF( .NOT.( WNTSNN .OR. WNTSNE ) )
                    292:      $            MAXWRK = MAX( MAXWRK, N*N + 2*N )
                    293:             ELSE
                    294:                MINWRK = 2*N
                    295:                IF( .NOT.( WNTSNN .OR. WNTSNE ) )
                    296:      $            MINWRK = MAX( MINWRK, N*N + 2*N )
                    297:                MAXWRK = MAX( MAXWRK, HSWORK )
                    298:                MAXWRK = MAX( MAXWRK, N + ( N - 1 )*ILAENV( 1, 'ZUNGHR',
                    299:      $                       ' ', N, 1, N, -1 ) )
                    300:                IF( .NOT.( WNTSNN .OR. WNTSNE ) )
                    301:      $            MAXWRK = MAX( MAXWRK, N*N + 2*N )
                    302:                MAXWRK = MAX( MAXWRK, 2*N )
                    303:             END IF
                    304:             MAXWRK = MAX( MAXWRK, MINWRK )
                    305:          END IF
                    306:          WORK( 1 ) = MAXWRK
                    307: *
                    308:          IF( LWORK.LT.MINWRK .AND. .NOT.LQUERY ) THEN
                    309:             INFO = -20
                    310:          END IF
                    311:       END IF
                    312: *
                    313:       IF( INFO.NE.0 ) THEN
                    314:          CALL XERBLA( 'ZGEEVX', -INFO )
                    315:          RETURN
                    316:       ELSE IF( LQUERY ) THEN
                    317:          RETURN
                    318:       END IF
                    319: *
                    320: *     Quick return if possible
                    321: *
                    322:       IF( N.EQ.0 )
                    323:      $   RETURN
                    324: *
                    325: *     Get machine constants
                    326: *
                    327:       EPS = DLAMCH( 'P' )
                    328:       SMLNUM = DLAMCH( 'S' )
                    329:       BIGNUM = ONE / SMLNUM
                    330:       CALL DLABAD( SMLNUM, BIGNUM )
                    331:       SMLNUM = SQRT( SMLNUM ) / EPS
                    332:       BIGNUM = ONE / SMLNUM
                    333: *
                    334: *     Scale A if max element outside range [SMLNUM,BIGNUM]
                    335: *
                    336:       ICOND = 0
                    337:       ANRM = ZLANGE( 'M', N, N, A, LDA, DUM )
                    338:       SCALEA = .FALSE.
                    339:       IF( ANRM.GT.ZERO .AND. ANRM.LT.SMLNUM ) THEN
                    340:          SCALEA = .TRUE.
                    341:          CSCALE = SMLNUM
                    342:       ELSE IF( ANRM.GT.BIGNUM ) THEN
                    343:          SCALEA = .TRUE.
                    344:          CSCALE = BIGNUM
                    345:       END IF
                    346:       IF( SCALEA )
                    347:      $   CALL ZLASCL( 'G', 0, 0, ANRM, CSCALE, N, N, A, LDA, IERR )
                    348: *
                    349: *     Balance the matrix and compute ABNRM
                    350: *
                    351:       CALL ZGEBAL( BALANC, N, A, LDA, ILO, IHI, SCALE, IERR )
                    352:       ABNRM = ZLANGE( '1', N, N, A, LDA, DUM )
                    353:       IF( SCALEA ) THEN
                    354:          DUM( 1 ) = ABNRM
                    355:          CALL DLASCL( 'G', 0, 0, CSCALE, ANRM, 1, 1, DUM, 1, IERR )
                    356:          ABNRM = DUM( 1 )
                    357:       END IF
                    358: *
                    359: *     Reduce to upper Hessenberg form
                    360: *     (CWorkspace: need 2*N, prefer N+N*NB)
                    361: *     (RWorkspace: none)
                    362: *
                    363:       ITAU = 1
                    364:       IWRK = ITAU + N
                    365:       CALL ZGEHRD( N, ILO, IHI, A, LDA, WORK( ITAU ), WORK( IWRK ),
                    366:      $             LWORK-IWRK+1, IERR )
                    367: *
                    368:       IF( WANTVL ) THEN
                    369: *
                    370: *        Want left eigenvectors
                    371: *        Copy Householder vectors to VL
                    372: *
                    373:          SIDE = 'L'
                    374:          CALL ZLACPY( 'L', N, N, A, LDA, VL, LDVL )
                    375: *
                    376: *        Generate unitary matrix in VL
                    377: *        (CWorkspace: need 2*N-1, prefer N+(N-1)*NB)
                    378: *        (RWorkspace: none)
                    379: *
                    380:          CALL ZUNGHR( N, ILO, IHI, VL, LDVL, WORK( ITAU ), WORK( IWRK ),
                    381:      $                LWORK-IWRK+1, IERR )
                    382: *
                    383: *        Perform QR iteration, accumulating Schur vectors in VL
                    384: *        (CWorkspace: need 1, prefer HSWORK (see comments) )
                    385: *        (RWorkspace: none)
                    386: *
                    387:          IWRK = ITAU
                    388:          CALL ZHSEQR( 'S', 'V', N, ILO, IHI, A, LDA, W, VL, LDVL,
                    389:      $                WORK( IWRK ), LWORK-IWRK+1, INFO )
                    390: *
                    391:          IF( WANTVR ) THEN
                    392: *
                    393: *           Want left and right eigenvectors
                    394: *           Copy Schur vectors to VR
                    395: *
                    396:             SIDE = 'B'
                    397:             CALL ZLACPY( 'F', N, N, VL, LDVL, VR, LDVR )
                    398:          END IF
                    399: *
                    400:       ELSE IF( WANTVR ) THEN
                    401: *
                    402: *        Want right eigenvectors
                    403: *        Copy Householder vectors to VR
                    404: *
                    405:          SIDE = 'R'
                    406:          CALL ZLACPY( 'L', N, N, A, LDA, VR, LDVR )
                    407: *
                    408: *        Generate unitary matrix in VR
                    409: *        (CWorkspace: need 2*N-1, prefer N+(N-1)*NB)
                    410: *        (RWorkspace: none)
                    411: *
                    412:          CALL ZUNGHR( N, ILO, IHI, VR, LDVR, WORK( ITAU ), WORK( IWRK ),
                    413:      $                LWORK-IWRK+1, IERR )
                    414: *
                    415: *        Perform QR iteration, accumulating Schur vectors in VR
                    416: *        (CWorkspace: need 1, prefer HSWORK (see comments) )
                    417: *        (RWorkspace: none)
                    418: *
                    419:          IWRK = ITAU
                    420:          CALL ZHSEQR( 'S', 'V', N, ILO, IHI, A, LDA, W, VR, LDVR,
                    421:      $                WORK( IWRK ), LWORK-IWRK+1, INFO )
                    422: *
                    423:       ELSE
                    424: *
                    425: *        Compute eigenvalues only
                    426: *        If condition numbers desired, compute Schur form
                    427: *
                    428:          IF( WNTSNN ) THEN
                    429:             JOB = 'E'
                    430:          ELSE
                    431:             JOB = 'S'
                    432:          END IF
                    433: *
                    434: *        (CWorkspace: need 1, prefer HSWORK (see comments) )
                    435: *        (RWorkspace: none)
                    436: *
                    437:          IWRK = ITAU
                    438:          CALL ZHSEQR( JOB, 'N', N, ILO, IHI, A, LDA, W, VR, LDVR,
                    439:      $                WORK( IWRK ), LWORK-IWRK+1, INFO )
                    440:       END IF
                    441: *
                    442: *     If INFO > 0 from ZHSEQR, then quit
                    443: *
                    444:       IF( INFO.GT.0 )
                    445:      $   GO TO 50
                    446: *
                    447:       IF( WANTVL .OR. WANTVR ) THEN
                    448: *
                    449: *        Compute left and/or right eigenvectors
                    450: *        (CWorkspace: need 2*N)
                    451: *        (RWorkspace: need N)
                    452: *
                    453:          CALL ZTREVC( SIDE, 'B', SELECT, N, A, LDA, VL, LDVL, VR, LDVR,
                    454:      $                N, NOUT, WORK( IWRK ), RWORK, IERR )
                    455:       END IF
                    456: *
                    457: *     Compute condition numbers if desired
                    458: *     (CWorkspace: need N*N+2*N unless SENSE = 'E')
                    459: *     (RWorkspace: need 2*N unless SENSE = 'E')
                    460: *
                    461:       IF( .NOT.WNTSNN ) THEN
                    462:          CALL ZTRSNA( SENSE, 'A', SELECT, N, A, LDA, VL, LDVL, VR, LDVR,
                    463:      $                RCONDE, RCONDV, N, NOUT, WORK( IWRK ), N, RWORK,
                    464:      $                ICOND )
                    465:       END IF
                    466: *
                    467:       IF( WANTVL ) THEN
                    468: *
                    469: *        Undo balancing of left eigenvectors
                    470: *
                    471:          CALL ZGEBAK( BALANC, 'L', N, ILO, IHI, SCALE, N, VL, LDVL,
                    472:      $                IERR )
                    473: *
                    474: *        Normalize left eigenvectors and make largest component real
                    475: *
                    476:          DO 20 I = 1, N
                    477:             SCL = ONE / DZNRM2( N, VL( 1, I ), 1 )
                    478:             CALL ZDSCAL( N, SCL, VL( 1, I ), 1 )
                    479:             DO 10 K = 1, N
                    480:                RWORK( K ) = DBLE( VL( K, I ) )**2 +
                    481:      $                      DIMAG( VL( K, I ) )**2
                    482:    10       CONTINUE
                    483:             K = IDAMAX( N, RWORK, 1 )
                    484:             TMP = DCONJG( VL( K, I ) ) / SQRT( RWORK( K ) )
                    485:             CALL ZSCAL( N, TMP, VL( 1, I ), 1 )
                    486:             VL( K, I ) = DCMPLX( DBLE( VL( K, I ) ), ZERO )
                    487:    20    CONTINUE
                    488:       END IF
                    489: *
                    490:       IF( WANTVR ) THEN
                    491: *
                    492: *        Undo balancing of right eigenvectors
                    493: *
                    494:          CALL ZGEBAK( BALANC, 'R', N, ILO, IHI, SCALE, N, VR, LDVR,
                    495:      $                IERR )
                    496: *
                    497: *        Normalize right eigenvectors and make largest component real
                    498: *
                    499:          DO 40 I = 1, N
                    500:             SCL = ONE / DZNRM2( N, VR( 1, I ), 1 )
                    501:             CALL ZDSCAL( N, SCL, VR( 1, I ), 1 )
                    502:             DO 30 K = 1, N
                    503:                RWORK( K ) = DBLE( VR( K, I ) )**2 +
                    504:      $                      DIMAG( VR( K, I ) )**2
                    505:    30       CONTINUE
                    506:             K = IDAMAX( N, RWORK, 1 )
                    507:             TMP = DCONJG( VR( K, I ) ) / SQRT( RWORK( K ) )
                    508:             CALL ZSCAL( N, TMP, VR( 1, I ), 1 )
                    509:             VR( K, I ) = DCMPLX( DBLE( VR( K, I ) ), ZERO )
                    510:    40    CONTINUE
                    511:       END IF
                    512: *
                    513: *     Undo scaling if necessary
                    514: *
                    515:    50 CONTINUE
                    516:       IF( SCALEA ) THEN
                    517:          CALL ZLASCL( 'G', 0, 0, CSCALE, ANRM, N-INFO, 1, W( INFO+1 ),
                    518:      $                MAX( N-INFO, 1 ), IERR )
                    519:          IF( INFO.EQ.0 ) THEN
                    520:             IF( ( WNTSNV .OR. WNTSNB ) .AND. ICOND.EQ.0 )
                    521:      $         CALL DLASCL( 'G', 0, 0, CSCALE, ANRM, N, 1, RCONDV, N,
                    522:      $                      IERR )
                    523:          ELSE
                    524:             CALL ZLASCL( 'G', 0, 0, CSCALE, ANRM, ILO-1, 1, W, N, IERR )
                    525:          END IF
                    526:       END IF
                    527: *
                    528:       WORK( 1 ) = MAXWRK
                    529:       RETURN
                    530: *
                    531: *     End of ZGEEVX
                    532: *
                    533:       END

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