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LAPACK 3.11.0
LAPACK: Linear Algebra PACKage
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LAPACK 3.11.0
LAPACK: Linear Algebra PACKage
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| subroutine ctrexc | ( | character | COMPQ, |
| integer | N, | ||
| complex, dimension( ldt, * ) | T, | ||
| integer | LDT, | ||
| complex, dimension( ldq, * ) | Q, | ||
| integer | LDQ, | ||
| integer | IFST, | ||
| integer | ILST, | ||
| integer | INFO | ||
| ) |
CTREXC
Download CTREXC + dependencies [TGZ] [ZIP] [TXT]
CTREXC reorders the Schur factorization of a complex matrix A = Q*T*Q**H, so that the diagonal element of T with row index IFST is moved to row ILST. The Schur form T is reordered by a unitary similarity transformation Z**H*T*Z, and optionally the matrix Q of Schur vectors is updated by postmultplying it with Z.
| [in] | COMPQ | COMPQ is CHARACTER*1
= 'V': update the matrix Q of Schur vectors;
= 'N': do not update Q. |
| [in] | N | N is INTEGER
The order of the matrix T. N >= 0.
If N == 0 arguments ILST and IFST may be any value. |
| [in,out] | T | T is COMPLEX array, dimension (LDT,N)
On entry, the upper triangular matrix T.
On exit, the reordered upper triangular matrix. |
| [in] | LDT | LDT is INTEGER
The leading dimension of the array T. LDT >= max(1,N). |
| [in,out] | Q | Q is COMPLEX array, dimension (LDQ,N)
On entry, if COMPQ = 'V', the matrix Q of Schur vectors.
On exit, if COMPQ = 'V', Q has been postmultiplied by the
unitary transformation matrix Z which reorders T.
If COMPQ = 'N', Q is not referenced. |
| [in] | LDQ | LDQ is INTEGER
The leading dimension of the array Q. LDQ >= 1, and if
COMPQ = 'V', LDQ >= max(1,N). |
| [in] | IFST | IFST is INTEGER |
| [in] | ILST | ILST is INTEGER
Specify the reordering of the diagonal elements of T:
The element with row index IFST is moved to row ILST by a
sequence of transpositions between adjacent elements.
1 <= IFST <= N; 1 <= ILST <= N. |
| [out] | INFO | INFO is INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value |
1.9.4