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/* lapack/complex16/ztrexc.f -- translated by f2c (version 20090411).
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
*/
#ifdef __cplusplus
extern "C" {
#endif
#include "v3p_netlib.h"
/* Table of constant values */
static integer c__1 = 1;
/*< SUBROUTINE ZTREXC( COMPQ, N, T, LDT, Q, LDQ, IFST, ILST, INFO ) >*/
/* Subroutine */ int ztrexc_(char *compq, integer *n, doublecomplex *t,
integer *ldt, doublecomplex *q, integer *ldq, integer *ifst, integer *
ilst, integer *info, ftnlen compq_len)
{
/* System generated locals */
integer q_dim1, q_offset, t_dim1, t_offset, i__1, i__2, i__3;
doublecomplex z__1;
/* Builtin functions */
void d_cnjg(doublecomplex *, doublecomplex *);
/* Local variables */
integer k, m1, m2, m3;
doublereal cs;
doublecomplex t11, t22, sn, temp;
extern /* Subroutine */ int zrot_(integer *, doublecomplex *, integer *,
doublecomplex *, integer *, doublereal *, doublecomplex *);
extern logical lsame_(const char *, const char *, ftnlen, ftnlen);
logical wantq;
extern /* Subroutine */ int xerbla_(char *, integer *, ftnlen), zlartg_(
doublecomplex *, doublecomplex *, doublereal *, doublecomplex *,
doublecomplex *);
(void)compq_len;
/* -- LAPACK routine (version 3.2) -- */
/* -- LAPACK is a software package provided by Univ. of Tennessee, -- */
/* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- */
/* November 2006 */
/* .. Scalar Arguments .. */
/*< CHARACTER COMPQ >*/
/*< INTEGER IFST, ILST, INFO, LDQ, LDT, N >*/
/* .. */
/* .. Array Arguments .. */
/*< 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 transformation 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 = -i, the i-th argument had an illegal value */
/* ===================================================================== */
/* .. Local Scalars .. */
/*< LOGICAL WANTQ >*/
/*< INTEGER K, M1, M2, M3 >*/
/*< DOUBLE PRECISION CS >*/
/*< COMPLEX*16 SN, T11, T22, TEMP >*/
/* .. */
/* .. External Functions .. */
/*< LOGICAL LSAME >*/
/*< EXTERNAL LSAME >*/
/* .. */
/* .. External Subroutines .. */
/*< EXTERNAL XERBLA, ZLARTG, ZROT >*/
/* .. */
/* .. Intrinsic Functions .. */
/*< INTRINSIC DCONJG, MAX >*/
/* .. */
/* .. Executable Statements .. */
/* Decode and test the input parameters. */
/*< INFO = 0 >*/
/* Parameter adjustments */
t_dim1 = *ldt;
t_offset = 1 + t_dim1;
t -= t_offset;
q_dim1 = *ldq;
q_offset = 1 + q_dim1;
q -= q_offset;
/* Function Body */
*info = 0;
/*< WANTQ = LSAME( COMPQ, 'V' ) >*/
wantq = lsame_(compq, "V", (ftnlen)1, (ftnlen)1);
/*< IF( .NOT.LSAME( COMPQ, 'N' ) .AND. .NOT.WANTQ ) THEN >*/
if (! lsame_(compq, "N", (ftnlen)1, (ftnlen)1) && ! wantq) {
/*< INFO = -1 >*/
*info = -1;
/*< ELSE IF( N.LT.0 ) THEN >*/
} else if (*n < 0) {
/*< INFO = -2 >*/
*info = -2;
/*< ELSE IF( LDT.LT.MAX( 1, N ) ) THEN >*/
} else if (*ldt < max(1,*n)) {
/*< INFO = -4 >*/
*info = -4;
/*< ELSE IF( LDQ.LT.1 .OR. ( WANTQ .AND. LDQ.LT.MAX( 1, N ) ) ) THEN >*/
} else if (*ldq < 1 || (wantq && *ldq < max(1,*n))) {
/*< INFO = -6 >*/
*info = -6;
/*< ELSE IF( IFST.LT.1 .OR. IFST.GT.N ) THEN >*/
} else if (*ifst < 1 || *ifst > *n) {
/*< INFO = -7 >*/
*info = -7;
/*< ELSE IF( ILST.LT.1 .OR. ILST.GT.N ) THEN >*/
} else if (*ilst < 1 || *ilst > *n) {
/*< INFO = -8 >*/
*info = -8;
/*< END IF >*/
}
/*< IF( INFO.NE.0 ) THEN >*/
if (*info != 0) {
/*< CALL XERBLA( 'ZTREXC', -INFO ) >*/
i__1 = -(*info);
xerbla_("ZTREXC", &i__1, (ftnlen)6);
/*< RETURN >*/
return 0;
/*< END IF >*/
}
/* Quick return if possible */
/*< >*/
if (*n == 1 || *ifst == *ilst) {
return 0;
}
/*< IF( IFST.LT.ILST ) THEN >*/
if (*ifst < *ilst) {
/* Move the IFST-th diagonal element forward down the diagonal. */
/*< M1 = 0 >*/
m1 = 0;
/*< M2 = -1 >*/
m2 = -1;
/*< M3 = 1 >*/
m3 = 1;
/*< ELSE >*/
} else {
/* Move the IFST-th diagonal element backward up the diagonal. */
/*< M1 = -1 >*/
m1 = -1;
/*< M2 = 0 >*/
m2 = 0;
/*< M3 = -1 >*/
m3 = -1;
/*< END IF >*/
}
/*< DO 10 K = IFST + M1, ILST + M2, M3 >*/
i__1 = *ilst + m2;
i__2 = m3;
for (k = *ifst + m1; i__2 < 0 ? k >= i__1 : k <= i__1; k += i__2) {
/* Interchange the k-th and (k+1)-th diagonal elements. */
/*< T11 = T( K, K ) >*/
i__3 = k + k * t_dim1;
t11.r = t[i__3].r, t11.i = t[i__3].i;
/*< T22 = T( K+1, K+1 ) >*/
i__3 = k + 1 + (k + 1) * t_dim1;
t22.r = t[i__3].r, t22.i = t[i__3].i;
/* Determine the transformation to perform the interchange. */
/*< CALL ZLARTG( T( K, K+1 ), T22-T11, CS, SN, TEMP ) >*/
z__1.r = t22.r - t11.r, z__1.i = t22.i - t11.i;
zlartg_(&t[k + (k + 1) * t_dim1], &z__1, &cs, &sn, &temp);
/* Apply transformation to the matrix T. */
/*< >*/
if (k + 2 <= *n) {
i__3 = *n - k - 1;
zrot_(&i__3, &t[k + (k + 2) * t_dim1], ldt, &t[k + 1 + (k + 2) *
t_dim1], ldt, &cs, &sn);
}
/*< >*/
i__3 = k - 1;
d_cnjg(&z__1, &sn);
zrot_(&i__3, &t[k * t_dim1 + 1], &c__1, &t[(k + 1) * t_dim1 + 1], &
c__1, &cs, &z__1);
/*< T( K, K ) = T22 >*/
i__3 = k + k * t_dim1;
t[i__3].r = t22.r, t[i__3].i = t22.i;
/*< T( K+1, K+1 ) = T11 >*/
i__3 = k + 1 + (k + 1) * t_dim1;
t[i__3].r = t11.r, t[i__3].i = t11.i;
/*< IF( WANTQ ) THEN >*/
if (wantq) {
/* Accumulate transformation in the matrix Q. */
/*< >*/
d_cnjg(&z__1, &sn);
zrot_(n, &q[k * q_dim1 + 1], &c__1, &q[(k + 1) * q_dim1 + 1], &
c__1, &cs, &z__1);
/*< END IF >*/
}
/*< 10 CONTINUE >*/
/* L10: */
}
/*< RETURN >*/
return 0;
/* End of ZTREXC */
/*< END >*/
} /* ztrexc_ */
#ifdef __cplusplus
}
#endif
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