  Quick Navigator

 Search Site Miscellaneous Server Agreement Year 2038 Credits   zggbak.f(3) LAPACK zggbak.f(3)

zggbak.f -

# SYNOPSIS

## Functions/Subroutines

subroutine zggbak (JOB, SIDE, N, ILO, IHI, LSCALE, RSCALE, M, V, LDV, INFO)

ZGGBAK

# Function/Subroutine Documentation

## subroutine zggbak (characterJOB, characterSIDE, integerN, integerILO, integerIHI, double precision, dimension( * )LSCALE, double precision, dimension( * )RSCALE, integerM, complex*16, dimension( ldv, * )V, integerLDV, integerINFO)

ZGGBAK
Purpose:
``` ZGGBAK forms the right or left eigenvectors of a complex generalized
eigenvalue problem A*x = lambda*B*x, by backward transformation on
the computed eigenvectors of the balanced pair of matrices output by
ZGGBAL.
```
Parameters:
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 ZGGBAL.
```
SIDE
```          SIDE is CHARACTER*1
= 'R':  V contains right eigenvectors;
= 'L':  V contains left eigenvectors.
```
N
```          N is INTEGER
The number of rows of the matrix V.  N >= 0.
```
ILO
```          ILO is INTEGER
```
IHI
```          IHI is INTEGER
The integers ILO and IHI determined by ZGGBAL.
1 <= ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if N=0.
```
LSCALE
```          LSCALE is DOUBLE PRECISION array, dimension (N)
Details of the permutations and/or scaling factors applied
to the left side of A and B, as returned by ZGGBAL.
```
RSCALE
```          RSCALE is DOUBLE PRECISION array, dimension (N)
Details of the permutations and/or scaling factors applied
to the right side of A and B, as returned by ZGGBAL.
```
M
```          M is INTEGER
The number of columns of the matrix V.  M >= 0.
```
V
```          V is COMPLEX*16 array, dimension (LDV,M)
On entry, the matrix of right or left eigenvectors to be
transformed, as returned by ZTGEVC.
On exit, V is overwritten by the transformed eigenvectors.
```
LDV
```          LDV is INTEGER
The leading dimension of the matrix V. LDV >= max(1,N).
```
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
NAG Ltd.
Date:
November 2011
Further Details:
```  See R.C. Ward, Balancing the generalized eigenvalue problem,
SIAM J. Sci. Stat. Comp. 2 (1981), 141-152.
```
Definition at line 148 of file zggbak.f.

# Author

Generated automatically by Doxygen for LAPACK from the source code.
 Sat Nov 16 2013 Version 3.4.2

Search for    or go to Top of page |  Section 3 |  Main Index Visit the GSP FreeBSD Man Page Interface.
Output converted with ManDoc.