ztrexc (l)  Linux Manuals
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
Command to display ztrexc
manual in Linux: $ man l ztrexc
NAME
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
SYNOPSIS
 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

= aqVaq: update the matrix Q of Schur vectors;
= aqNaq: 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 = aqVaq, the matrix Q of Schur vectors.
On exit, if COMPQ = aqVaq, Q has been postmultiplied by the
unitary transformation matrix Z which reorders T.
If COMPQ = aqNaq, 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 = i, the ith argument had an illegal value
Pages related to ztrexc
 ztrexc (3)
 ztrevc (l)  computes some or all of the right and/or left eigenvectors of a complex upper triangular matrix T
 ztrcon (l)  estimates the reciprocal of the condition number of a triangular matrix A, in either the 1norm or the infinitynorm
 ztrmm (l)  performs one of the matrixmatrix operations B := alpha*op( A )*B, or B := alpha*B*op( A ) where alpha is a scalar, B is an m by n matrix, A is a unit, or nonunit, upper or lower triangular matrix and op( A ) is one of op( A ) = A or op( A ) = Aaq or op( A ) = conjg( Aaq )
 ztrmv (l)  performs one of the matrixvector operations x := A*x, or x := Aaq*x, or x := conjg( Aaq )*x,
 ztrrfs (l)  provides error bounds and backward error estimates for the solution to a system of linear equations with a triangular coefficient matrix
 ztrsen (l)  reorders the Schur factorization of a complex matrix A = Q*T*Q**H, so that a selected cluster of eigenvalues appears in the leading positions on the diagonal of the upper triangular matrix T, and the leading columns of Q form an orthonormal basis of the corresponding right invariant subspace
 ztrsm (l)  solves one of the matrix equations op( A )*X = alpha*B, or X*op( A ) = alpha*B,