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LAPACK
3.7.0
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 |
Definition at line 128 of file ctrexc.f.