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template<typename T>
void ggbak(char *job, char *side, integer *n, integer *ilo, integer *ihi, T *lscale, T *rscale, integer *m, T *v, integer *ldv, integer *info)# GGBAK forms the right or left eigenvectors of a real generalized eigenvalue problem.
Purpose:
GGBAK forms the right or left eigenvectors of a real generalized eigenvalue problem A*x = lambda*B*x, by backward transformation on the computed eigenvectors of the balanced pair of matrices output by GGBAL.
- Parameters:
JOB – [in]
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 SGGBAL.SIDE – [in]
SIDE is CHARACTER*1
= ‘R’: V contains right eigenvectors;
= ‘L’: V contains left eigenvectors.N – [in]
N is INTEGER
The number of rows of the matrix V. N >= 0.
ILO – [in] ILO is INTEGER
IHI – [in]
IHI is INTEGER
The integers ILO and IHI determined by SGGBAL.
1 <= ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if N=0.LSCALE – [in]
LSCALE is REAL array, dimension (N)
Details of the permutations and/or scaling factors applied to the left side of A and B, as returned by SGGBAL.
RSCALE – [in]
RSCALE is REAL array, dimension (N)
Details of the permutations and/or scaling factors applied to the right side of A and B, as returned by SGGBAL.
M – [in]
M is INTEGER
The number of columns of the matrix V. M >= 0.
V – [inout]
V is REAL array, dimension (LDV,M)
On entry, the matrix of right or left eigenvectors to be transformed, as returned by STGEVC.
On exit, V is overwritten by the transformed eigenvectors.LDV – [in]
LDV is INTEGER
The leading dimension of the matrix V. LDV >= fla_max(1,N).
INFO – [out]
INFO is INTEGER
= 0: successful exit.
< 0: if INFO = -i, the i-th argument had an illegal value.