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## zgebak()

subroutine zgebak | ( | character | job,
|  | character | side,
|  | integer | n,
|  | integer | ilo,
|  | integer | ihi,
|  | double precision, dimension( * ) | scale,
|  | integer | m,
|  | complex*16, dimension( ldv, * ) | v,
|  | integer | ldv,
|  | integer | info )

ZGEBAK

Download ZGEBAK + dependencies [TGZ] [ZIP] [TXT]

Purpose:

      !>
      !> ZGEBAK forms the right or left eigenvectors of a complex general
      !> matrix by backward transformation on the computed eigenvectors of the
      !> balanced matrix output by ZGEBAL.
      !>

Parameters

  [in]

  JOB

      !>          JOB is CHARACTER*1
      !>          Specifies the type of backward transformation required:
      !>          = 'N': do nothing, return immediately;
      !>          = 'P': do backward transformation for permutation only;
      !>          = 'S': do backward transformation for scaling only;
      !>          = 'B': do backward transformations for both permutation and
      !>                 scaling.
      !>          JOB must be the same as the argument JOB supplied to ZGEBAL.
      !>

  [in]

  SIDE

      !>          SIDE is CHARACTER*1
      !>          = 'R':  V contains right eigenvectors;
      !>          = 'L':  V contains left eigenvectors.
      !>

  [in]

  N

      !>          N is INTEGER
      !>          The number of rows of the matrix V.  N >= 0.
      !>

  [in]

  ILO

      !>          ILO is INTEGER
      !>

  [in]

  IHI

      !>          IHI is INTEGER
      !>          The integers ILO and IHI determined by ZGEBAL.
      !>          1 <= ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if N=0.
      !>

  [in]

  SCALE

      !>          SCALE is DOUBLE PRECISION array, dimension (N)
      !>          Details of the permutation and scaling factors, as returned
      !>          by ZGEBAL.
      !>

  [in]

  M

      !>          M is INTEGER
      !>          The number of columns of the matrix V.  M >= 0.
      !>

  [in,out]

  V

      !>          V is COMPLEX*16 array, dimension (LDV,M)
      !>          On entry, the matrix of right or left eigenvectors to be
      !>          transformed, as returned by ZHSEIN or ZTREVC.
      !>          On exit, V is overwritten by the transformed eigenvectors.
      !>

  [in]

  LDV

      !>          LDV is INTEGER
      !>          The leading dimension of the array V. LDV >= max(1,N).
      !>

  [out]

  INFO

      !>          INFO is INTEGER
      !>          = 0:  successful exit
      !>          < 0:  if INFO = -i, the i-th argument had an illegal value.
      !>

Author
  Univ. of Tennessee
  Univ. of California Berkeley
  Univ. of Colorado Denver
  NAG Ltd.