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ctrexc.f

NAME

ctrexc.f −

SYNOPSIS

Functions/Subroutines

subroutine ctrexc (COMPQ, N, T, LDT, Q, LDQ, IFST, ILST, INFO)
CTREXC

Function/Subroutine Documentation

subroutine ctrexc (characterCOMPQ, integerN, complex, dimension( ldt, * )T, integerLDT, complex, dimension( ldq, * )Q, integerLDQ, integerIFST, integerILST, integerINFO)
CTREXC

Purpose:

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.

Parameters:

COMPQ

COMPQ is CHARACTER*1
= ’V’: update the matrix Q of Schur vectors;
= ’N’: do not update Q.

N

N is INTEGER
The order of the matrix T. N >= 0.

T

T is COMPLEX array, dimension (LDT,N)
On entry, the upper triangular matrix T.
On exit, the reordered upper triangular matrix.

LDT

LDT is INTEGER
The leading dimension of the array T. LDT >= max(1,N).

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.

LDQ

LDQ is INTEGER
The leading dimension of the array Q. LDQ >= max(1,N).

IFST

IFST is INTEGER

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.

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

Univ. of Colorado Denver

NAG Ltd.

Date:

November 2011

Definition at line 125 of file ctrexc.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

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