ctrexc-f(3)

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

 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 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

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