ctrexc.f (3) Linux Manual Page

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

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