# ctrexc(3) [centos man page]

ctrexc.f(3) LAPACK ctrexc.f(3)NAME

ctrexc.f-SYNOPSIS

Functions/Subroutines subroutine ctrexc (COMPQ, N, T, LDT, Q, LDQ, IFST, ILST, INFO) CTREXCFunction/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 =, 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.-iAuthorGenerated automatically by Doxygen for LAPACK from the source code.Version 3.4.2Tue Sep 25 2012 ctrexc.f(3)

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ZTREXC(l)) ZTREXC(l)NAME

ZTREXC - reorder 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 ILSTSYNOPSIS

SUBROUTINE ZTREXC( COMPQ, N, T, LDT, Q, LDQ, IFST, ILST, INFO ) CHARACTER COMPQ INTEGER IFST, ILST, INFO, LDQ, LDT, N COMPLEX*16 Q( LDQ, * ), T( LDT, * )PURPOSE

ZTREXC 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.ARGUMENTS

COMPQ (input) CHARACTER*1 = 'V': update the matrix Q of Schur vectors; = 'N': do not update Q. N (input) INTEGER The order of the matrix T. N >= 0. T (input/output) COMPLEX*16 array, dimension (LDT,N) On entry, the upper triangular matrix T. On exit, the reordered upper triangular matrix. LDT (input) INTEGER The leading dimension of the array T. LDT >= max(1,N). Q (input/output) COMPLEX*16 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 trans- formation matrix Z which reorders T. If COMPQ = 'N', Q is not referenced. LDQ (input) INTEGER The leading dimension of the array Q. LDQ >= max(1,N). IFST (input) INTEGER ILST (input) 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 (output) INTEGER = 0: successful exit < 0: if INFO =, the i-th argument had an illegal value-iLAPACK version 3.015 June 2000 ZTREXC(l)