nag_dgebak (f08njc) is intended to be used after a real nonsymmetric matrix
has been balanced by
nag_dgebal (f08nhc), and eigenvectors of the balanced matrix
have subsequently been computed.
For a description of balancing, see the document for
nag_dgebal (f08nhc). The balanced matrix
is obtained as
, where
is a permutation matrix and
is a diagonal scaling matrix. This function transforms left or right eigenvectors as follows:
- if is a right eigenvector of , is a right eigenvector of ;
- if is a left eigenvector of , is a left eigenvector of .
None.
- NE_ALLOC_FAIL
-
Dynamic memory allocation failed.
See
Section 2.3.1.2 in How to Use the NAG Library and its Documentation for further information.
- NE_BAD_PARAM
-
On entry, argument had an illegal value.
- NE_INT
-
On entry, .
Constraint: .
On entry, .
Constraint: .
On entry, .
Constraint: .
- NE_INT_2
-
On entry, and .
Constraint: .
On entry, and .
Constraint: .
- NE_INT_3
-
On entry, , and .
Constraint: if , ;
if , and .
- NE_INTERNAL_ERROR
-
An internal error has occurred in this function. Check the function call and any array sizes. If the call is correct then please contact
NAG for assistance.
See
Section 2.7.6 in How to Use the NAG Library and its Documentation for further information.
- NE_NO_LICENCE
-
Your licence key may have expired or may not have been installed correctly.
See
Section 2.7.5 in How to Use the NAG Library and its Documentation for further information.
The errors are negligible.
Please consult the
x06 Chapter Introduction for information on how to control and interrogate the OpenMP environment used within this function. Please also consult the
Users' Note for your implementation for any additional implementation-specific information.
The complex analogue of this function is
nag_zgebak (f08nwc).