SGEBAK
November 2006
Purpose
SGEBAK forms the right or left eigenvectors of a real general matrix
by backward transformation on the computed eigenvectors of the
balanced matrix output by SGEBAL.
by backward transformation on the computed eigenvectors of the
balanced matrix output by SGEBAL.
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 SGEBAL. |
| 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 SGEBAL.
1 <= ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if N=0. |
| SCALE |
(input) REAL array, dimension (N)
Details of the permutation and scaling factors, as returned
by SGEBAL. |
| M |
(input) INTEGER
The number of columns of the matrix V. M >= 0.
|
| V |
(input/output) REAL array, dimension (LDV,M)
On entry, the matrix of right or left eigenvectors to be
transformed, as returned by SHSEIN or STREVC. 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. |