DGEBAK(3)      LAPACK routine of NEC Numeric Library Collection      DGEBAK(3)



NAME
       DGEBAK

SYNOPSIS
       SUBROUTINE DGEBAK (JOB, SIDE, N, ILO, IHI, SCALE, M, V, LDV, INFO)



PURPOSE
            DGEBAK forms the right or left eigenvectors of a real general matrix
            by backward transformation on the computed eigenvectors of the
            balanced matrix output by DGEBAL.




ARGUMENTS
           JOB       (input)
                     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 DGEBAL.

           SIDE      (input)
                     SIDE is CHARACTER*1
                     = 'R':  V contains right eigenvectors;
                     = 'L':  V contains left eigenvectors.

           N         (input)
                     N is INTEGER
                     The number of rows of the matrix V.  N >= 0.

           ILO       (input)
                     ILO is INTEGER

           IHI       (input)
                     IHI is INTEGER
                     The integers ILO and IHI determined by DGEBAL.
                     1 <= ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if N=0.

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

           M         (input)
                     M is INTEGER
                     The number of columns of the matrix V.  M >= 0.

           V         (input/output)
                     V is DOUBLE PRECISION array, dimension (LDV,M)
                     On entry, the matrix of right or left eigenvectors to be
                     transformed, as returned by DHSEIN or DTREVC.
                     On exit, V is overwritten by the transformed eigenvectors.

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

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



LAPACK routine                  31 October 2017                      DGEBAK(3)