naginterfaces.library.lapackeig.ztrexc¶
- naginterfaces.library.lapackeig.ztrexc(compq, t, q, ifst, ilst)[source]¶
ztrexc
reorders the Schur factorization of a complex general matrix.For full information please refer to the NAG Library document for f08qt
https://support.nag.com/numeric/nl/nagdoc_30.2/flhtml/f08/f08qtf.html
- Parameters
- compqstr, length 1
Indicates whether the matrix of Schur vectors is to be updated.
The matrix of Schur vectors is updated.
No Schur vectors are updated.
- tcomplex, array-like, shape
The upper triangular matrix , as returned by
zhseqr()
.- qcomplex, array-like, shape
Note: the required extent for this argument in dimension 1 is determined as follows: if : ; if : ; otherwise: .
Note: the required extent for this argument in dimension 2 is determined as follows: if : ; if : ; otherwise: .
If , must contain the unitary matrix of Schur vectors.
- ifstint
and must specify the reordering of the diagonal elements of . The element with row index is moved to row by a sequence of exchanges between adjacent elements.
- ilstint
and must specify the reordering of the diagonal elements of . The element with row index is moved to row by a sequence of exchanges between adjacent elements.
- Returns
- tcomplex, ndarray, shape
is overwritten by the updated matrix .
- qcomplex, ndarray, shape
If , contains the updated matrix of Schur vectors.
If , is not referenced.
- Raises
- NagValueError
- (errno )
On entry, error in parameter .
Constraint: or .
- (errno )
On entry, error in parameter .
Constraint: .
- (errno )
On entry, error in parameter .
Constraint: .
- (errno )
On entry, error in parameter .
Constraint: .
- Notes
ztrexc
reorders the Schur factorization of a complex general matrix , so that the diagonal element of with row index is moved to row .The reordered Schur form is computed by a unitary similarity transformation: . Optionally the updated matrix of Schur vectors is computed as , giving .
- References
Golub, G H and Van Loan, C F, 1996, Matrix Computations, (3rd Edition), Johns Hopkins University Press, Baltimore