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/* ctgexc.f -- translated by f2c (version 20061008).
You must link the resulting object file with libf2c:
on Microsoft Windows system, link with libf2c.lib;
on Linux or Unix systems, link with .../path/to/libf2c.a -lm
or, if you install libf2c.a in a standard place, with -lf2c -lm
-- in that order, at the end of the command line, as in
cc *.o -lf2c -lm
Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
http://www.netlib.org/f2c/libf2c.zip
*/
#include "f2c.h"
#include "blaswrap.h"
/* Subroutine */ int ctgexc_(logical *wantq, logical *wantz, integer *n,
complex *a, integer *lda, complex *b, integer *ldb, complex *q,
integer *ldq, complex *z__, integer *ldz, integer *ifst, integer *
ilst, integer *info)
{
/* System generated locals */
integer a_dim1, a_offset, b_dim1, b_offset, q_dim1, q_offset, z_dim1,
z_offset, i__1;
/* Local variables */
integer here;
extern /* Subroutine */ int ctgex2_(logical *, logical *, integer *,
complex *, integer *, complex *, integer *, complex *, integer *,
complex *, integer *, integer *, integer *), xerbla_(char *,
integer *);
/* -- LAPACK routine (version 3.2) -- */
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/* November 2006 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* CTGEXC reorders the generalized Schur decomposition of a complex */
/* matrix pair (A,B), using an unitary equivalence transformation */
/* (A, B) := Q * (A, B) * Z', so that the diagonal block of (A, B) with */
/* row index IFST is moved to row ILST. */
/* (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)' = Q(out) * A(out) * Z(out)' */
/* Q(in) * B(in) * Z(in)' = Q(out) * B(out) * Z(out)' */
/* Arguments */
/* ========= */
/* WANTQ (input) LOGICAL */
/* .TRUE. : update the left transformation matrix Q; */
/* .FALSE.: do not update Q. */
/* WANTZ (input) LOGICAL */
/* .TRUE. : update the right transformation matrix Z; */
/* .FALSE.: do not update Z. */
/* N (input) INTEGER */
/* The order of the matrices A and B. N >= 0. */
/* A (input/output) COMPLEX array, dimension (LDA,N) */
/* On entry, the upper triangular matrix A in the pair (A, B). */
/* On exit, the updated matrix A. */
/* LDA (input) INTEGER */
/* The leading dimension of the array A. LDA >= max(1,N). */
/* B (input/output) COMPLEX array, dimension (LDB,N) */
/* On entry, the upper triangular matrix B in the pair (A, B). */
/* On exit, the updated matrix B. */
/* LDB (input) INTEGER */
/* The leading dimension of the array B. LDB >= max(1,N). */
/* Q (input/output) COMPLEX array, dimension (LDZ,N) */
/* On entry, if WANTQ = .TRUE., the unitary matrix Q. */
/* On exit, the updated matrix Q. */
/* If WANTQ = .FALSE., Q is not referenced. */
/* LDQ (input) INTEGER */
/* The leading dimension of the array Q. LDQ >= 1; */
/* If WANTQ = .TRUE., LDQ >= N. */
/* Z (input/output) COMPLEX array, dimension (LDZ,N) */
/* On entry, if WANTZ = .TRUE., the unitary matrix Z. */
/* On exit, the updated matrix Z. */
/* If WANTZ = .FALSE., Z is not referenced. */
/* LDZ (input) INTEGER */
/* The leading dimension of the array Z. LDZ >= 1; */
/* If WANTZ = .TRUE., LDZ >= N. */
/* IFST (input) INTEGER */
/* ILST (input/output) INTEGER */
/* Specify the reordering of the diagonal blocks of (A, B). */
/* The block with row index IFST is moved to row ILST, by a */
/* sequence of swapping between adjacent blocks. */
/* INFO (output) INTEGER */
/* =0: Successful exit. */
/* <0: if INFO = -i, the i-th argument had an illegal value. */
/* =1: The transformed matrix pair (A, B) would be too far */
/* from generalized Schur form; the problem is ill- */
/* conditioned. (A, B) may have been partially reordered, */
/* and ILST points to the first row of the current */
/* position of the block being moved. */
/* Further Details */
/* =============== */
/* Based on contributions by */
/* Bo Kagstrom and Peter Poromaa, Department of Computing Science, */
/* Umea University, S-901 87 Umea, Sweden. */
/* [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. */
/* [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. */
/* [3] B. Kagstrom and P. Poromaa, LAPACK-Style Algorithms and Software */
/* for Solving the Generalized Sylvester Equation and Estimating the */
/* Separation between Regular Matrix Pairs, Report UMINF - 93.23, */
/* Department of Computing Science, Umea University, S-901 87 Umea, */
/* Sweden, December 1993, Revised April 1994, Also as LAPACK working */
/* Note 75. To appear in ACM Trans. on Math. Software, Vol 22, No 1, */
/* 1996. */
/* ===================================================================== */
/* .. Local Scalars .. */
/* .. */
/* .. External Subroutines .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* .. Executable Statements .. */
/* Decode and test input arguments. */
/* Parameter adjustments */
a_dim1 = *lda;
a_offset = 1 + a_dim1;
a -= a_offset;
b_dim1 = *ldb;
b_offset = 1 + b_dim1;
b -= b_offset;
q_dim1 = *ldq;
q_offset = 1 + q_dim1;
q -= q_offset;
z_dim1 = *ldz;
z_offset = 1 + z_dim1;
z__ -= z_offset;
/* Function Body */
*info = 0;
if (*n < 0) {
*info = -3;
} else if (*lda < max(1,*n)) {
*info = -5;
} else if (*ldb < max(1,*n)) {
*info = -7;
} else if (*ldq < 1 || *wantq && *ldq < max(1,*n)) {
*info = -9;
} else if (*ldz < 1 || *wantz && *ldz < max(1,*n)) {
*info = -11;
} else if (*ifst < 1 || *ifst > *n) {
*info = -12;
} else if (*ilst < 1 || *ilst > *n) {
*info = -13;
}
if (*info != 0) {
i__1 = -(*info);
xerbla_("CTGEXC", &i__1);
return 0;
}
/* Quick return if possible */
if (*n <= 1) {
return 0;
}
if (*ifst == *ilst) {
return 0;
}
if (*ifst < *ilst) {
here = *ifst;
L10:
/* Swap with next one below */
ctgex2_(wantq, wantz, n, &a[a_offset], lda, &b[b_offset], ldb, &q[
q_offset], ldq, &z__[z_offset], ldz, &here, info);
if (*info != 0) {
*ilst = here;
return 0;
}
++here;
if (here < *ilst) {
goto L10;
}
--here;
} else {
here = *ifst - 1;
L20:
/* Swap with next one above */
ctgex2_(wantq, wantz, n, &a[a_offset], lda, &b[b_offset], ldb, &q[
q_offset], ldq, &z__[z_offset], ldz, &here, info);
if (*info != 0) {
*ilst = here;
return 0;
}
--here;
if (here >= *ilst) {
goto L20;
}
++here;
}
*ilst = here;
return 0;
/* End of CTGEXC */
} /* ctgexc_ */
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