.TH "ztgex2.f" 3 "Sun May 26 2013" "Version 3.4.1" "LAPACK" \" -*- nroff -*-
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.nh
.SH NAME
ztgex2.f \- 
.SH SYNOPSIS
.br
.PP
.SS "Functions/Subroutines"

.in +1c
.ti -1c
.RI "subroutine \fBztgex2\fP (WANTQ, WANTZ, N, A, LDA, B, LDB, Q, LDQ, Z, LDZ, J1, INFO)"
.br
.RI "\fI\fBZTGEX2\fP \fP"
.in -1c
.SH "Function/Subroutine Documentation"
.PP 
.SS "subroutine ztgex2 (logicalWANTQ, logicalWANTZ, integerN, complex*16, dimension( lda, * )A, integerLDA, complex*16, dimension( ldb, * )B, integerLDB, complex*16, dimension( ldq, * )Q, integerLDQ, complex*16, dimension( ldz, * )Z, integerLDZ, integerJ1, integerINFO)"

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\fBZTGEX2\fP  
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\fBPurpose: \fP
.RS 4

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.nf
 ZTGEX2 swaps adjacent diagonal 1 by 1 blocks (A11,B11) and (A22,B22)
 in an upper triangular matrix pair (A, B) by an unitary equivalence
 transformation.

 (A, B) must be in generalized Schur canonical form, that is, A and
 B are both upper triangular.

 Optionally, the matrices Q and Z of generalized Schur vectors are
 updated.

        Q(in) * A(in) * Z(in)**H = Q(out) * A(out) * Z(out)**H
        Q(in) * B(in) * Z(in)**H = Q(out) * B(out) * Z(out)**H
.fi
.PP
 
.RE
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\fBParameters:\fP
.RS 4
\fIWANTQ\fP 
.PP
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          WANTQ is LOGICAL
          .TRUE. : update the left transformation matrix Q;
          .FALSE.: do not update Q.
.fi
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.br
\fIWANTZ\fP 
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.nf
          WANTZ is LOGICAL
          .TRUE. : update the right transformation matrix Z;
          .FALSE.: do not update Z.
.fi
.PP
.br
\fIN\fP 
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          N is INTEGER
          The order of the matrices A and B. N >= 0.
.fi
.PP
.br
\fIA\fP 
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          A is COMPLEX*16 arrays, dimensions (LDA,N)
          On entry, the matrix A in the pair (A, B).
          On exit, the updated matrix A.
.fi
.PP
.br
\fILDA\fP 
.PP
.nf
          LDA is INTEGER
          The leading dimension of the array A. LDA >= max(1,N).
.fi
.PP
.br
\fIB\fP 
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          B is COMPLEX*16 arrays, dimensions (LDB,N)
          On entry, the matrix B in the pair (A, B).
          On exit, the updated matrix B.
.fi
.PP
.br
\fILDB\fP 
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          LDB is INTEGER
          The leading dimension of the array B. LDB >= max(1,N).
.fi
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.br
\fIQ\fP 
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          Q is COMPLEX*16 array, dimension (LDZ,N)
          If WANTQ = .TRUE, on entry, the unitary matrix Q. On exit,
          the updated matrix Q.
          Not referenced if WANTQ = .FALSE..
.fi
.PP
.br
\fILDQ\fP 
.PP
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          LDQ is INTEGER
          The leading dimension of the array Q. LDQ >= 1;
          If WANTQ = .TRUE., LDQ >= N.
.fi
.PP
.br
\fIZ\fP 
.PP
.nf
          Z is COMPLEX*16 array, dimension (LDZ,N)
          If WANTZ = .TRUE, on entry, the unitary matrix Z. On exit,
          the updated matrix Z.
          Not referenced if WANTZ = .FALSE..
.fi
.PP
.br
\fILDZ\fP 
.PP
.nf
          LDZ is INTEGER
          The leading dimension of the array Z. LDZ >= 1;
          If WANTZ = .TRUE., LDZ >= N.
.fi
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.br
\fIJ1\fP 
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.nf
          J1 is INTEGER
          The index to the first block (A11, B11).
.fi
.PP
.br
\fIINFO\fP 
.PP
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          INFO is INTEGER
           =0:  Successful exit.
           =1:  The transformed matrix pair (A, B) would be too far
                from generalized Schur form; the problem is ill-
                conditioned. 
.fi
.PP
 
.RE
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\fBAuthor:\fP
.RS 4
Univ\&. of Tennessee 
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Univ\&. of California Berkeley 
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Univ\&. of Colorado Denver 
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NAG Ltd\&. 
.RE
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\fBDate:\fP
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November 2011 
.RE
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\fBFurther Details: \fP
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In the current code both weak and strong stability tests are performed\&. The user can omit the strong stability test by changing the internal logical parameter WANDS to \&.FALSE\&.\&. See ref\&. [2] for details\&. 
.RE
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\fBContributors: \fP
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Bo Kagstrom and Peter Poromaa, Department of Computing Science, Umea University, S-901 87 Umea, Sweden\&. 
.RE
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\fBReferences: \fP
.RS 4
[1] B\&. Kagstrom; A Direct Method for Reordering Eigenvalues in the Generalized Real Schur Form of a Regular Matrix Pair (A, B), in M\&.S\&. Moonen et al (eds), Linear Algebra for Large Scale and Real-Time Applications, Kluwer Academic Publ\&. 1993, pp 195-218\&. 
.br
 [2] B\&. Kagstrom and P\&. Poromaa; Computing Eigenspaces with Specified Eigenvalues of a Regular Matrix Pair (A, B) and Condition Estimation: Theory, Algorithms and Software, Report UMINF-94\&.04, Department of Computing Science, Umea University, S-901 87 Umea, Sweden, 1994\&. Also as LAPACK Working Note 87\&. To appear in Numerical Algorithms, 1996\&. 
.RE
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Definition at line 190 of file ztgex2\&.f\&.
.SH "Author"
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Generated automatically by Doxygen for LAPACK from the source code\&.