DGEBAK
November 2006
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.
by backward transformation on the computed eigenvectors of the
balanced matrix output by DGEBAL.
Arguments
| JOB |
(input) 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) CHARACTER*1
= 'R': V contains right eigenvectors;
= 'L': V contains left eigenvectors. |
| N |
(input) INTEGER
The number of rows of the matrix V. N >= 0.
|
| ILO |
(input) INTEGER
|
| IHI |
(input) 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) DOUBLE PRECISION array, dimension (N)
Details of the permutation and scaling factors, as returned
by DGEBAL. |
| M |
(input) INTEGER
The number of columns of the matrix V. M >= 0.
|
| V |
(input/output) 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) INTEGER
The leading dimension of the array V. LDV >= max(1,N).
|
| INFO |
(output) INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value. |