int dtrsen_(char *job, char *compq, int *select, int
*n, double *t, int *ldt, double *q, int *ldq,
double *wr, double *wi, int *m, double *s, double
*sep, double *work, int *lwork, int *iwork, int *
liwork, int *info)
{
/* System generated locals */
int q_dim1, q_offset, t_dim1, t_offset, i__1, i__2;
double d__1, d__2;
/* Builtin functions */
double sqrt(double);
/* Local variables */
int k, n1, n2, kk, nn, ks;
double est;
int kase;
int pair;
int ierr;
int swap;
double scale;
extern int lsame_(char *, char *);
int isave[3], lwmin;
int wantq, wants;
double rnorm;
extern int dlacn2_(int *, double *, double *,
int *, double *, int *, int *);
extern double dlange_(char *, int *, int *, double *,
int *, double *);
extern int dlacpy_(char *, int *, int *,
double *, int *, double *, int *),
xerbla_(char *, int *);
int wantbh;
extern int dtrexc_(char *, int *, double *,
int *, double *, int *, int *, int *,
double *, int *);
int liwmin;
int wantsp, lquery;
extern int dtrsyl_(char *, char *, int *, int *,
int *, double *, int *, double *, int *,
double *, int *, double *, int *);
/* -- LAPACK routine (version 3.2) -- */
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/* November 2006 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* DTRSEN reorders the float Schur factorization of a float matrix */
/* A = Q*T*Q**T, so that a selected cluster of eigenvalues appears in */
/* the leading diagonal blocks of the upper quasi-triangular matrix T, */
/* and the leading columns of Q form an orthonormal basis of the */
/* corresponding right invariant subspace. */
/* Optionally the routine computes the reciprocal condition numbers of */
/* the cluster of eigenvalues and/or the invariant subspace. */
/* T must be in Schur canonical form (as returned by DHSEQR), that is, */
/* block upper triangular with 1-by-1 and 2-by-2 diagonal blocks; each */
/* 2-by-2 diagonal block has its diagonal elemnts equal and its */
/* off-diagonal elements of opposite sign. */
/* Arguments */
/* ========= */
/* JOB (input) CHARACTER*1 */
/* Specifies whether condition numbers are required for the */
/* cluster of eigenvalues (S) or the invariant subspace (SEP): */
/* = 'N': none; */
/* = 'E': for eigenvalues only (S); */
/* = 'V': for invariant subspace only (SEP); */
/* = 'B': for both eigenvalues and invariant subspace (S and */
/* SEP). */
/* COMPQ (input) CHARACTER*1 */
/* = 'V': update the matrix Q of Schur vectors; */
/* = 'N': do not update Q. */
/* SELECT (input) LOGICAL array, dimension (N) */
/* SELECT specifies the eigenvalues in the selected cluster. To */
/* select a float eigenvalue w(j), SELECT(j) must be set to */
/* .TRUE.. To select a complex conjugate pair of eigenvalues */
/* w(j) and w(j+1), corresponding to a 2-by-2 diagonal block, */
/* either SELECT(j) or SELECT(j+1) or both must be set to */
/* .TRUE.; a complex conjugate pair of eigenvalues must be */
/* either both included in the cluster or both excluded. */
/* N (input) INTEGER */
/* The order of the matrix T. N >= 0. */
/* T (input/output) DOUBLE PRECISION array, dimension (LDT,N) */
/* On entry, the upper quasi-triangular matrix T, in Schur */
/* canonical form. */
/* On exit, T is overwritten by the reordered matrix T, again in */
/* Schur canonical form, with the selected eigenvalues in the */
/* leading diagonal blocks. */
/* LDT (input) INTEGER */
/* The leading dimension of the array T. LDT >= MAX(1,N). */
/* Q (input/output) DOUBLE PRECISION 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 */
/* orthogonal transformation matrix which reorders T; the */
/* leading M columns of Q form an orthonormal basis for the */
/* specified invariant subspace. */
/* If COMPQ = 'N', Q is not referenced. */
/* LDQ (input) INTEGER */
/* The leading dimension of the array Q. */
/* LDQ >= 1; and if COMPQ = 'V', LDQ >= N. */
/* WR (output) DOUBLE PRECISION array, dimension (N) */
/* WI (output) DOUBLE PRECISION array, dimension (N) */
/* The float and imaginary parts, respectively, of the reordered */
/* eigenvalues of T. The eigenvalues are stored in the same */
/* order as on the diagonal of T, with WR(i) = T(i,i) and, if */
/* T(i:i+1,i:i+1) is a 2-by-2 diagonal block, WI(i) > 0 and */
/* WI(i+1) = -WI(i). Note that if a complex eigenvalue is */
/* sufficiently ill-conditioned, then its value may differ */
/* significantly from its value before reordering. */
/* M (output) INTEGER */
/* The dimension of the specified invariant subspace. */
/* 0 < = M <= N. */
/* S (output) DOUBLE PRECISION */
/* If JOB = 'E' or 'B', S is a lower bound on the reciprocal */
/* condition number for the selected cluster of eigenvalues. */
/* S cannot underestimate the true reciprocal condition number */
/* by more than a factor of sqrt(N). If M = 0 or N, S = 1. */
/* If JOB = 'N' or 'V', S is not referenced. */
/* SEP (output) DOUBLE PRECISION */
/* If JOB = 'V' or 'B', SEP is the estimated reciprocal */
/* condition number of the specified invariant subspace. If */
/* M = 0 or N, SEP = norm(T). */
/* If JOB = 'N' or 'E', SEP is not referenced. */
/* WORK (workspace/output) DOUBLE PRECISION array, dimension (MAX(1,LWORK)) */
/* On exit, if INFO = 0, WORK(1) returns the optimal LWORK. */
/* LWORK (input) INTEGER */
/* The dimension of the array WORK. */
/* If JOB = 'N', LWORK >= MAX(1,N); */
/* if JOB = 'E', LWORK >= MAX(1,M*(N-M)); */
/* if JOB = 'V' or 'B', LWORK >= MAX(1,2*M*(N-M)). */
/* If LWORK = -1, then a workspace query is assumed; the routine */
/* only calculates the optimal size of the WORK array, returns */
/* this value as the first entry of the WORK array, and no error */
/* message related to LWORK is issued by XERBLA. */
/* IWORK (workspace) INTEGER array, dimension (MAX(1,LIWORK)) */
/* On exit, if INFO = 0, IWORK(1) returns the optimal LIWORK. */
/* LIWORK (input) INTEGER */
/* The dimension of the array IWORK. */
/* If JOB = 'N' or 'E', LIWORK >= 1; */
/* if JOB = 'V' or 'B', LIWORK >= MAX(1,M*(N-M)). */
/* If LIWORK = -1, then a workspace query is assumed; the */
/* routine only calculates the optimal size of the IWORK array, */
/* returns this value as the first entry of the IWORK array, and */
/* no error message related to LIWORK is issued by XERBLA. */
/* INFO (output) INTEGER */
/* = 0: successful exit */
/* < 0: if INFO = -i, the i-th argument had an illegal value */
/* = 1: reordering of T failed because some eigenvalues are too */
/* close to separate (the problem is very ill-conditioned); */
/* T may have been partially reordered, and WR and WI */
/* contain the eigenvalues in the same order as in T; S and */
/* SEP (if requested) are set to zero. */
/* Further Details */
/* =============== */
/* DTRSEN first collects the selected eigenvalues by computing an */
/* orthogonal transformation Z to move them to the top left corner of T. */
/* In other words, the selected eigenvalues are the eigenvalues of T11 */
/* in: */
/* Z'*T*Z = ( T11 T12 ) n1 */
/* ( 0 T22 ) n2 */
/* n1 n2 */
/* where N = n1+n2 and Z' means the transpose of Z. The first n1 columns */
/* of Z span the specified invariant subspace of T. */
/* If T has been obtained from the float Schur factorization of a matrix */
/* A = Q*T*Q', then the reordered float Schur factorization of A is given */
/* by A = (Q*Z)*(Z'*T*Z)*(Q*Z)', and the first n1 columns of Q*Z span */
/* the corresponding invariant subspace of A. */
/* The reciprocal condition number of the average of the eigenvalues of */
/* T11 may be returned in S. S lies between 0 (very badly conditioned) */
/* and 1 (very well conditioned). It is computed as follows. First we */
/* compute R so that */
/* P = ( I R ) n1 */
/* ( 0 0 ) n2 */
/* n1 n2 */
/* is the projector on the invariant subspace associated with T11. */
/* R is the solution of the Sylvester equation: */
/* T11*R - R*T22 = T12. */
/* Let F-norm(M) denote the Frobenius-norm of M and 2-norm(M) denote */
/* the two-norm of M. Then S is computed as the lower bound */
/* (1 + F-norm(R)**2)**(-1/2) */
/* on the reciprocal of 2-norm(P), the true reciprocal condition number. */
/* S cannot underestimate 1 / 2-norm(P) by more than a factor of */
/* sqrt(N). */
/* An approximate error bound for the computed average of the */
/* eigenvalues of T11 is */
/* EPS * norm(T) / S */
/* where EPS is the machine precision. */
/* The reciprocal condition number of the right invariant subspace */
/* spanned by the first n1 columns of Z (or of Q*Z) is returned in SEP. */
/* SEP is defined as the separation of T11 and T22: */
/* sep( T11, T22 ) = sigma-MIN( C ) */
/* where sigma-MIN(C) is the smallest singular value of the */
/* n1*n2-by-n1*n2 matrix */
/* C = kprod( I(n2), T11 ) - kprod( transpose(T22), I(n1) ) */
/* I(m) is an m by m identity matrix, and kprod denotes the Kronecker */
/* product. We estimate sigma-MIN(C) by the reciprocal of an estimate of */
/* the 1-norm of inverse(C). The true reciprocal 1-norm of inverse(C) */
/* cannot differ from sigma-MIN(C) by more than a factor of sqrt(n1*n2). */
/* When SEP is small, small changes in T can cause large changes in */
/* the invariant subspace. An approximate bound on the maximum angular */
/* error in the computed right invariant subspace is */
/* EPS * norm(T) / SEP */
/* ===================================================================== */
/* .. Parameters .. */
/* .. */
/* .. Local Scalars .. */
/* .. */
/* .. Local Arrays .. */
/* .. */
/* .. External Functions .. */
/* .. */
/* .. External Subroutines .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* .. Executable Statements .. */
/* Decode and test the input parameters */
/* Parameter adjustments */
--select;
t_dim1 = *ldt;
t_offset = 1 + t_dim1;
t -= t_offset;
q_dim1 = *ldq;
q_offset = 1 + q_dim1;
q -= q_offset;
--wr;
--wi;
--work;
--iwork;
/* Function Body */
wantbh = lsame_(job, "B");
wants = lsame_(job, "E") || wantbh;
wantsp = lsame_(job, "V") || wantbh;
wantq = lsame_(compq, "V");
*info = 0;
lquery = *lwork == -1;
if (! lsame_(job, "N") && ! wants && ! wantsp) {
*info = -1;
} else if (! lsame_(compq, "N") && ! wantq) {
*info = -2;
} else if (*n < 0) {
*info = -4;
} else if (*ldt < MAX(1,*n)) {
*info = -6;
} else if (*ldq < 1 || wantq && *ldq < *n) {
*info = -8;
} else {
/* Set M to the dimension of the specified invariant subspace, */
/* and test LWORK and LIWORK. */
*m = 0;
pair = FALSE;
i__1 = *n;
for (k = 1; k <= i__1; ++k) {
if (pair) {
pair = FALSE;
} else {
if (k < *n) {
if (t[k + 1 + k * t_dim1] == 0.) {
if (select[k]) {
++(*m);
}
} else {
pair = TRUE;
if (select[k] || select[k + 1]) {
*m += 2;
}
}
} else {
if (select[*n]) {
++(*m);
}
}
}
/* L10: */
}
n1 = *m;
n2 = *n - *m;
nn = n1 * n2;
if (wantsp) {
/* Computing MAX */
i__1 = 1, i__2 = nn << 1;
lwmin = MAX(i__1,i__2);
liwmin = MAX(1,nn);
} else if (lsame_(job, "N")) {
lwmin = MAX(1,*n);
liwmin = 1;
} else if (lsame_(job, "E")) {
lwmin = MAX(1,nn);
liwmin = 1;
}
if (*lwork < lwmin && ! lquery) {
*info = -15;
} else if (*liwork < liwmin && ! lquery) {
*info = -17;
}
}
if (*info == 0) {
work[1] = (double) lwmin;
iwork[1] = liwmin;
}
if (*info != 0) {
i__1 = -(*info);
xerbla_("DTRSEN", &i__1);
return 0;
} else if (lquery) {
return 0;
}
/* Quick return if possible. */
if (*m == *n || *m == 0) {
if (wants) {
*s = 1.;
}
if (wantsp) {
*sep = dlange_("1", n, n, &t[t_offset], ldt, &work[1]);
}
goto L40;
}
/* Collect the selected blocks at the top-left corner of T. */
ks = 0;
pair = FALSE;
i__1 = *n;
for (k = 1; k <= i__1; ++k) {
if (pair) {
pair = FALSE;
} else {
swap = select[k];
if (k < *n) {
if (t[k + 1 + k * t_dim1] != 0.) {
pair = TRUE;
swap = swap || select[k + 1];
}
}
if (swap) {
++ks;
/* Swap the K-th block to position KS. */
ierr = 0;
kk = k;
if (k != ks) {
dtrexc_(compq, n, &t[t_offset], ldt, &q[q_offset], ldq, &
kk, &ks, &work[1], &ierr);
}
if (ierr == 1 || ierr == 2) {
/* Blocks too close to swap: exit. */
*info = 1;
if (wants) {
*s = 0.;
}
if (wantsp) {
*sep = 0.;
}
goto L40;
}
if (pair) {
++ks;
}
}
}
/* L20: */
}
if (wants) {
/* Solve Sylvester equation for R: */
/* T11*R - R*T22 = scale*T12 */
dlacpy_("F", &n1, &n2, &t[(n1 + 1) * t_dim1 + 1], ldt, &work[1], &n1);
dtrsyl_("N", "N", &c_n1, &n1, &n2, &t[t_offset], ldt, &t[n1 + 1 + (n1
+ 1) * t_dim1], ldt, &work[1], &n1, &scale, &ierr);
/* Estimate the reciprocal of the condition number of the cluster */
/* of eigenvalues. */
rnorm = dlange_("F", &n1, &n2, &work[1], &n1, &work[1]);
if (rnorm == 0.) {
*s = 1.;
} else {
*s = scale / (sqrt(scale * scale / rnorm + rnorm) * sqrt(rnorm));
}
}
if (wantsp) {
/* Estimate sep(T11,T22). */
est = 0.;
kase = 0;
L30:
dlacn2_(&nn, &work[nn + 1], &work[1], &iwork[1], &est, &kase, isave);
if (kase != 0) {
if (kase == 1) {
/* Solve T11*R - R*T22 = scale*X. */
dtrsyl_("N", "N", &c_n1, &n1, &n2, &t[t_offset], ldt, &t[n1 +
1 + (n1 + 1) * t_dim1], ldt, &work[1], &n1, &scale, &
ierr);
} else {
/* Solve T11'*R - R*T22' = scale*X. */
dtrsyl_("T", "T", &c_n1, &n1, &n2, &t[t_offset], ldt, &t[n1 +
1 + (n1 + 1) * t_dim1], ldt, &work[1], &n1, &scale, &
ierr);
}
goto L30;
}
*sep = scale / est;
}
L40:
/* Store the output eigenvalues in WR and WI. */
i__1 = *n;
for (k = 1; k <= i__1; ++k) {
wr[k] = t[k + k * t_dim1];
wi[k] = 0.;
/* L50: */
}
i__1 = *n - 1;
for (k = 1; k <= i__1; ++k) {
if (t[k + 1 + k * t_dim1] != 0.) {
wi[k] = sqrt((d__1 = t[k + (k + 1) * t_dim1], ABS(d__1))) * sqrt((
d__2 = t[k + 1 + k * t_dim1], ABS(d__2)));
wi[k + 1] = -wi[k];
}
/* L60: */
}
work[1] = (double) lwmin;
iwork[1] = liwmin;
return 0;
/* End of DTRSEN */
} /* dtrsen_ */
int main(void)
{
/* Local scalars */
char compq, compq_i;
lapack_int n, n_i;
lapack_int ldt, ldt_i;
lapack_int ldt_r;
lapack_int ldq, ldq_i;
lapack_int ldq_r;
lapack_int ifst, ifst_i, ifst_save;
lapack_int ilst, ilst_i, ilst_save;
lapack_int info, info_i;
lapack_int i;
int failed;
/* Local arrays */
double *t = NULL, *t_i = NULL;
double *q = NULL, *q_i = NULL;
double *work = NULL, *work_i = NULL;
double *t_save = NULL;
double *q_save = NULL;
double *t_r = NULL;
double *q_r = NULL;
/* Iniitialize the scalar parameters */
init_scalars_dtrexc( &compq, &n, &ldt, &ldq, &ifst, &ilst );
ldt_r = n+2;
ldq_r = n+2;
compq_i = compq;
n_i = n;
ldt_i = ldt;
ldq_i = ldq;
ifst_i = ifst_save = ifst;
ilst_i = ilst_save = ilst;
/* Allocate memory for the LAPACK routine arrays */
t = (double *)LAPACKE_malloc( ldt*n * sizeof(double) );
q = (double *)LAPACKE_malloc( ldq*n * sizeof(double) );
work = (double *)LAPACKE_malloc( n * sizeof(double) );
/* Allocate memory for the C interface function arrays */
t_i = (double *)LAPACKE_malloc( ldt*n * sizeof(double) );
q_i = (double *)LAPACKE_malloc( ldq*n * sizeof(double) );
work_i = (double *)LAPACKE_malloc( n * sizeof(double) );
/* Allocate memory for the backup arrays */
t_save = (double *)LAPACKE_malloc( ldt*n * sizeof(double) );
q_save = (double *)LAPACKE_malloc( ldq*n * sizeof(double) );
/* Allocate memory for the row-major arrays */
t_r = (double *)LAPACKE_malloc( n*(n+2) * sizeof(double) );
q_r = (double *)LAPACKE_malloc( n*(n+2) * sizeof(double) );
/* Initialize input arrays */
init_t( ldt*n, t );
init_q( ldq*n, q );
init_work( n, work );
/* Backup the ouptut arrays */
for( i = 0; i < ldt*n; i++ ) {
t_save[i] = t[i];
}
for( i = 0; i < ldq*n; i++ ) {
q_save[i] = q[i];
}
/* Call the LAPACK routine */
dtrexc_( &compq, &n, t, &ldt, q, &ldq, &ifst, &ilst, work, &info );
/* Initialize input data, call the column-major middle-level
* interface to LAPACK routine and check the results */
ifst_i = ifst_save;
ilst_i = ilst_save;
for( i = 0; i < ldt*n; i++ ) {
t_i[i] = t_save[i];
}
for( i = 0; i < ldq*n; i++ ) {
q_i[i] = q_save[i];
}
for( i = 0; i < n; i++ ) {
work_i[i] = work[i];
}
info_i = LAPACKE_dtrexc_work( LAPACK_COL_MAJOR, compq_i, n_i, t_i, ldt_i,
q_i, ldq_i, &ifst_i, &ilst_i, work_i );
failed = compare_dtrexc( t, t_i, q, q_i, ifst, ifst_i, ilst, ilst_i, info,
info_i, compq, ldq, ldt, n );
if( failed == 0 ) {
printf( "PASSED: column-major middle-level interface to dtrexc\n" );
} else {
printf( "FAILED: column-major middle-level interface to dtrexc\n" );
}
/* Initialize input data, call the column-major high-level
* interface to LAPACK routine and check the results */
ifst_i = ifst_save;
ilst_i = ilst_save;
for( i = 0; i < ldt*n; i++ ) {
t_i[i] = t_save[i];
}
for( i = 0; i < ldq*n; i++ ) {
q_i[i] = q_save[i];
}
for( i = 0; i < n; i++ ) {
work_i[i] = work[i];
}
info_i = LAPACKE_dtrexc( LAPACK_COL_MAJOR, compq_i, n_i, t_i, ldt_i, q_i,
ldq_i, &ifst_i, &ilst_i );
failed = compare_dtrexc( t, t_i, q, q_i, ifst, ifst_i, ilst, ilst_i, info,
info_i, compq, ldq, ldt, n );
if( failed == 0 ) {
printf( "PASSED: column-major high-level interface to dtrexc\n" );
} else {
printf( "FAILED: column-major high-level interface to dtrexc\n" );
}
/* Initialize input data, call the row-major middle-level
* interface to LAPACK routine and check the results */
ifst_i = ifst_save;
ilst_i = ilst_save;
for( i = 0; i < ldt*n; i++ ) {
t_i[i] = t_save[i];
}
for( i = 0; i < ldq*n; i++ ) {
q_i[i] = q_save[i];
}
for( i = 0; i < n; i++ ) {
work_i[i] = work[i];
}
LAPACKE_dge_trans( LAPACK_COL_MAJOR, n, n, t_i, ldt, t_r, n+2 );
if( LAPACKE_lsame( compq, 'v' ) ) {
LAPACKE_dge_trans( LAPACK_COL_MAJOR, n, n, q_i, ldq, q_r, n+2 );
}
info_i = LAPACKE_dtrexc_work( LAPACK_ROW_MAJOR, compq_i, n_i, t_r, ldt_r,
q_r, ldq_r, &ifst_i, &ilst_i, work_i );
LAPACKE_dge_trans( LAPACK_ROW_MAJOR, n, n, t_r, n+2, t_i, ldt );
if( LAPACKE_lsame( compq, 'v' ) ) {
LAPACKE_dge_trans( LAPACK_ROW_MAJOR, n, n, q_r, n+2, q_i, ldq );
}
failed = compare_dtrexc( t, t_i, q, q_i, ifst, ifst_i, ilst, ilst_i, info,
info_i, compq, ldq, ldt, n );
if( failed == 0 ) {
printf( "PASSED: row-major middle-level interface to dtrexc\n" );
} else {
printf( "FAILED: row-major middle-level interface to dtrexc\n" );
}
/* Initialize input data, call the row-major high-level
* interface to LAPACK routine and check the results */
ifst_i = ifst_save;
ilst_i = ilst_save;
for( i = 0; i < ldt*n; i++ ) {
t_i[i] = t_save[i];
}
for( i = 0; i < ldq*n; i++ ) {
q_i[i] = q_save[i];
}
for( i = 0; i < n; i++ ) {
work_i[i] = work[i];
}
/* Init row_major arrays */
LAPACKE_dge_trans( LAPACK_COL_MAJOR, n, n, t_i, ldt, t_r, n+2 );
if( LAPACKE_lsame( compq, 'v' ) ) {
LAPACKE_dge_trans( LAPACK_COL_MAJOR, n, n, q_i, ldq, q_r, n+2 );
}
info_i = LAPACKE_dtrexc( LAPACK_ROW_MAJOR, compq_i, n_i, t_r, ldt_r, q_r,
ldq_r, &ifst_i, &ilst_i );
LAPACKE_dge_trans( LAPACK_ROW_MAJOR, n, n, t_r, n+2, t_i, ldt );
if( LAPACKE_lsame( compq, 'v' ) ) {
LAPACKE_dge_trans( LAPACK_ROW_MAJOR, n, n, q_r, n+2, q_i, ldq );
}
failed = compare_dtrexc( t, t_i, q, q_i, ifst, ifst_i, ilst, ilst_i, info,
info_i, compq, ldq, ldt, n );
if( failed == 0 ) {
printf( "PASSED: row-major high-level interface to dtrexc\n" );
} else {
printf( "FAILED: row-major high-level interface to dtrexc\n" );
}
/* Release memory */
if( t != NULL ) {
LAPACKE_free( t );
}
if( t_i != NULL ) {
LAPACKE_free( t_i );
}
if( t_r != NULL ) {
LAPACKE_free( t_r );
}
if( t_save != NULL ) {
LAPACKE_free( t_save );
}
if( q != NULL ) {
LAPACKE_free( q );
}
if( q_i != NULL ) {
LAPACKE_free( q_i );
}
if( q_r != NULL ) {
LAPACKE_free( q_r );
}
if( q_save != NULL ) {
LAPACKE_free( q_save );
}
if( work != NULL ) {
LAPACKE_free( work );
}
if( work_i != NULL ) {
LAPACKE_free( work_i );
}
return 0;
}
/* Subroutine */ int dget36_(doublereal *rmax, integer *lmax, integer *ninfo,
integer *knt, integer *nin)
{
/* System generated locals */
integer i__1, i__2;
/* Builtin functions */
integer s_rsle(cilist *), do_lio(integer *, integer *, char *, ftnlen),
e_rsle(void);
double d_sign(doublereal *, doublereal *);
/* Local variables */
integer i__, j, n;
doublereal q[100] /* was [10][10] */, t1[100] /* was [10][10] */,
t2[100] /* was [10][10] */;
integer loc;
doublereal eps, res, tmp[100] /* was [10][10] */;
integer ifst, ilst;
doublereal work[200];
integer info1, info2, ifst1, ifst2, ilst1, ilst2;
extern /* Subroutine */ int dhst01_(integer *, integer *, integer *,
doublereal *, integer *, doublereal *, integer *, doublereal *,
integer *, doublereal *, integer *, doublereal *);
extern doublereal dlamch_(char *);
extern /* Subroutine */ int dlacpy_(char *, integer *, integer *,
doublereal *, integer *, doublereal *, integer *),
dlaset_(char *, integer *, integer *, doublereal *, doublereal *,
doublereal *, integer *), dtrexc_(char *, integer *,
doublereal *, integer *, doublereal *, integer *, integer *,
integer *, doublereal *, integer *);
integer ifstsv;
doublereal result[2];
integer ilstsv;
/* Fortran I/O blocks */
static cilist io___2 = { 0, 0, 0, 0, 0 };
static cilist io___7 = { 0, 0, 0, 0, 0 };
/* -- LAPACK test routine (version 3.1) -- */
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/* November 2006 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* DGET36 tests DTREXC, a routine for moving blocks (either 1 by 1 or */
/* 2 by 2) on the diagonal of a matrix in real Schur form. Thus, DLAEXC */
/* computes an orthogonal matrix Q such that */
/* Q' * T1 * Q = T2 */
/* and where one of the diagonal blocks of T1 (the one at row IFST) has */
/* been moved to position ILST. */
/* The test code verifies that the residual Q'*T1*Q-T2 is small, that T2 */
/* is in Schur form, and that the final position of the IFST block is */
/* ILST (within +-1). */
/* The test matrices are read from a file with logical unit number NIN. */
/* Arguments */
/* ========== */
/* RMAX (output) DOUBLE PRECISION */
/* Value of the largest test ratio. */
/* LMAX (output) INTEGER */
/* Example number where largest test ratio achieved. */
/* NINFO (output) INTEGER array, dimension (3) */
/* NINFO(J) is the number of examples where INFO=J. */
/* KNT (output) INTEGER */
/* Total number of examples tested. */
/* NIN (input) INTEGER */
/* Input logical unit number. */
/* ===================================================================== */
/* .. Parameters .. */
/* .. */
/* .. Local Scalars .. */
/* .. */
/* .. Local Arrays .. */
/* .. */
/* .. External Functions .. */
/* .. */
/* .. External Subroutines .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* .. Executable Statements .. */
/* Parameter adjustments */
--ninfo;
/* Function Body */
eps = dlamch_("P");
*rmax = 0.;
*lmax = 0;
*knt = 0;
ninfo[1] = 0;
ninfo[2] = 0;
ninfo[3] = 0;
/* Read input data until N=0 */
L10:
io___2.ciunit = *nin;
s_rsle(&io___2);
do_lio(&c__3, &c__1, (char *)&n, (ftnlen)sizeof(integer));
do_lio(&c__3, &c__1, (char *)&ifst, (ftnlen)sizeof(integer));
do_lio(&c__3, &c__1, (char *)&ilst, (ftnlen)sizeof(integer));
e_rsle();
if (n == 0) {
return 0;
}
++(*knt);
i__1 = n;
for (i__ = 1; i__ <= i__1; ++i__) {
io___7.ciunit = *nin;
s_rsle(&io___7);
i__2 = n;
for (j = 1; j <= i__2; ++j) {
do_lio(&c__5, &c__1, (char *)&tmp[i__ + j * 10 - 11], (ftnlen)
sizeof(doublereal));
}
e_rsle();
/* L20: */
}
dlacpy_("F", &n, &n, tmp, &c__10, t1, &c__10);
dlacpy_("F", &n, &n, tmp, &c__10, t2, &c__10);
ifstsv = ifst;
ilstsv = ilst;
ifst1 = ifst;
ilst1 = ilst;
ifst2 = ifst;
ilst2 = ilst;
res = 0.;
/* Test without accumulating Q */
dlaset_("Full", &n, &n, &c_b21, &c_b22, q, &c__10);
dtrexc_("N", &n, t1, &c__10, q, &c__10, &ifst1, &ilst1, work, &info1);
i__1 = n;
for (i__ = 1; i__ <= i__1; ++i__) {
i__2 = n;
for (j = 1; j <= i__2; ++j) {
if (i__ == j && q[i__ + j * 10 - 11] != 1.) {
res += 1. / eps;
}
if (i__ != j && q[i__ + j * 10 - 11] != 0.) {
res += 1. / eps;
}
/* L30: */
}
/* L40: */
}
/* Test with accumulating Q */
dlaset_("Full", &n, &n, &c_b21, &c_b22, q, &c__10);
dtrexc_("V", &n, t2, &c__10, q, &c__10, &ifst2, &ilst2, work, &info2);
/* Compare T1 with T2 */
i__1 = n;
for (i__ = 1; i__ <= i__1; ++i__) {
i__2 = n;
for (j = 1; j <= i__2; ++j) {
if (t1[i__ + j * 10 - 11] != t2[i__ + j * 10 - 11]) {
res += 1. / eps;
}
/* L50: */
}
/* L60: */
}
if (ifst1 != ifst2) {
res += 1. / eps;
}
if (ilst1 != ilst2) {
res += 1. / eps;
}
if (info1 != info2) {
res += 1. / eps;
}
/* Test for successful reordering of T2 */
if (info2 != 0) {
++ninfo[info2];
} else {
if ((i__1 = ifst2 - ifstsv, abs(i__1)) > 1) {
res += 1. / eps;
}
if ((i__1 = ilst2 - ilstsv, abs(i__1)) > 1) {
res += 1. / eps;
}
}
/* Test for small residual, and orthogonality of Q */
dhst01_(&n, &c__1, &n, tmp, &c__10, t2, &c__10, q, &c__10, work, &c__200,
result);
res = res + result[0] + result[1];
/* Test for T2 being in Schur form */
loc = 1;
L70:
if (t2[loc + 1 + loc * 10 - 11] != 0.) {
/* 2 by 2 block */
if (t2[loc + (loc + 1) * 10 - 11] == 0. || t2[loc + loc * 10 - 11] !=
t2[loc + 1 + (loc + 1) * 10 - 11] || d_sign(&c_b22, &t2[loc +
(loc + 1) * 10 - 11]) == d_sign(&c_b22, &t2[loc + 1 + loc *
10 - 11])) {
res += 1. / eps;
}
i__1 = n;
for (i__ = loc + 2; i__ <= i__1; ++i__) {
if (t2[i__ + loc * 10 - 11] != 0.) {
res += 1. / res;
}
if (t2[i__ + (loc + 1) * 10 - 11] != 0.) {
res += 1. / res;
}
/* L80: */
}
loc += 2;
} else {
/* 1 by 1 block */
i__1 = n;
for (i__ = loc + 1; i__ <= i__1; ++i__) {
if (t2[i__ + loc * 10 - 11] != 0.) {
res += 1. / res;
}
/* L90: */
}
++loc;
}
if (loc < n) {
goto L70;
}
if (res > *rmax) {
*rmax = res;
*lmax = *knt;
}
goto L10;
/* End of DGET36 */
} /* dget36_ */
/* Subroutine */ int dlaqr2_(logical *wantt, logical *wantz, integer *n,
integer *ktop, integer *kbot, integer *nw, doublereal *h__, integer *
ldh, integer *iloz, integer *ihiz, doublereal *z__, integer *ldz,
integer *ns, integer *nd, doublereal *sr, doublereal *si, doublereal *
v, integer *ldv, integer *nh, doublereal *t, integer *ldt, integer *
nv, doublereal *wv, integer *ldwv, doublereal *work, integer *lwork)
{
/* System generated locals */
integer h_dim1, h_offset, t_dim1, t_offset, v_dim1, v_offset, wv_dim1,
wv_offset, z_dim1, z_offset, i__1, i__2, i__3, i__4;
doublereal d__1, d__2, d__3, d__4, d__5, d__6;
/* Builtin functions */
double sqrt(doublereal);
/* Local variables */
integer i__, j, k;
doublereal s, aa, bb, cc, dd, cs, sn;
integer jw;
doublereal evi, evk, foo;
integer kln;
doublereal tau, ulp;
integer lwk1, lwk2;
doublereal beta;
integer kend, kcol, info, ifst, ilst, ltop, krow;
extern /* Subroutine */ int dlarf_(char *, integer *, integer *,
doublereal *, integer *, doublereal *, doublereal *, integer *,
doublereal *), dgemm_(char *, char *, integer *, integer *
, integer *, doublereal *, doublereal *, integer *, doublereal *,
integer *, doublereal *, doublereal *, integer *);
logical bulge;
extern /* Subroutine */ int dcopy_(integer *, doublereal *, integer *,
doublereal *, integer *);
integer infqr, kwtop;
extern /* Subroutine */ int dlanv2_(doublereal *, doublereal *,
doublereal *, doublereal *, doublereal *, doublereal *,
doublereal *, doublereal *, doublereal *, doublereal *), dlabad_(
doublereal *, doublereal *);
extern doublereal dlamch_(char *);
extern /* Subroutine */ int dgehrd_(integer *, integer *, integer *,
doublereal *, integer *, doublereal *, doublereal *, integer *,
integer *), dlarfg_(integer *, doublereal *, doublereal *,
integer *, doublereal *), dlahqr_(logical *, logical *, integer *,
integer *, integer *, doublereal *, integer *, doublereal *,
doublereal *, integer *, integer *, doublereal *, integer *,
integer *), dlacpy_(char *, integer *, integer *, doublereal *,
integer *, doublereal *, integer *);
doublereal safmin;
extern /* Subroutine */ int dlaset_(char *, integer *, integer *,
doublereal *, doublereal *, doublereal *, integer *);
doublereal safmax;
extern /* Subroutine */ int dorghr_(integer *, integer *, integer *,
doublereal *, integer *, doublereal *, doublereal *, integer *,
integer *), dtrexc_(char *, integer *, doublereal *, integer *,
doublereal *, integer *, integer *, integer *, doublereal *,
integer *);
logical sorted;
doublereal smlnum;
integer lwkopt;
/* -- LAPACK auxiliary routine (version 3.1) -- */
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/* November 2006 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* This subroutine is identical to DLAQR3 except that it avoids */
/* recursion by calling DLAHQR instead of DLAQR4. */
/* ****************************************************************** */
/* Aggressive early deflation: */
/* This subroutine accepts as input an upper Hessenberg matrix */
/* H and performs an orthogonal similarity transformation */
/* designed to detect and deflate fully converged eigenvalues from */
/* a trailing principal submatrix. On output H has been over- */
/* written by a new Hessenberg matrix that is a perturbation of */
/* an orthogonal similarity transformation of H. It is to be */
/* hoped that the final version of H has many zero subdiagonal */
/* entries. */
/* ****************************************************************** */
/* WANTT (input) LOGICAL */
/* If .TRUE., then the Hessenberg matrix H is fully updated */
/* so that the quasi-triangular Schur factor may be */
/* computed (in cooperation with the calling subroutine). */
/* If .FALSE., then only enough of H is updated to preserve */
/* the eigenvalues. */
/* WANTZ (input) LOGICAL */
/* If .TRUE., then the orthogonal matrix Z is updated so */
/* so that the orthogonal Schur factor may be computed */
/* (in cooperation with the calling subroutine). */
/* If .FALSE., then Z is not referenced. */
/* N (input) INTEGER */
/* The order of the matrix H and (if WANTZ is .TRUE.) the */
/* order of the orthogonal matrix Z. */
/* KTOP (input) INTEGER */
/* It is assumed that either KTOP = 1 or H(KTOP,KTOP-1)=0. */
/* KBOT and KTOP together determine an isolated block */
/* along the diagonal of the Hessenberg matrix. */
/* KBOT (input) INTEGER */
/* It is assumed without a check that either */
/* KBOT = N or H(KBOT+1,KBOT)=0. KBOT and KTOP together */
/* determine an isolated block along the diagonal of the */
/* Hessenberg matrix. */
/* NW (input) INTEGER */
/* Deflation window size. 1 .LE. NW .LE. (KBOT-KTOP+1). */
/* H (input/output) DOUBLE PRECISION array, dimension (LDH,N) */
/* On input the initial N-by-N section of H stores the */
/* Hessenberg matrix undergoing aggressive early deflation. */
/* On output H has been transformed by an orthogonal */
/* similarity transformation, perturbed, and the returned */
/* to Hessenberg form that (it is to be hoped) has some */
/* zero subdiagonal entries. */
/* LDH (input) integer */
/* Leading dimension of H just as declared in the calling */
/* subroutine. N .LE. LDH */
/* ILOZ (input) INTEGER */
/* IHIZ (input) INTEGER */
/* Specify the rows of Z to which transformations must be */
/* applied if WANTZ is .TRUE.. 1 .LE. ILOZ .LE. IHIZ .LE. N. */
/* Z (input/output) DOUBLE PRECISION array, dimension (LDZ,IHI) */
/* IF WANTZ is .TRUE., then on output, the orthogonal */
/* similarity transformation mentioned above has been */
/* accumulated into Z(ILOZ:IHIZ,ILO:IHI) from the right. */
/* If WANTZ is .FALSE., then Z is unreferenced. */
/* LDZ (input) integer */
/* The leading dimension of Z just as declared in the */
/* calling subroutine. 1 .LE. LDZ. */
/* NS (output) integer */
/* The number of unconverged (ie approximate) eigenvalues */
/* returned in SR and SI that may be used as shifts by the */
/* calling subroutine. */
/* ND (output) integer */
/* The number of converged eigenvalues uncovered by this */
/* subroutine. */
/* SR (output) DOUBLE PRECISION array, dimension KBOT */
/* SI (output) DOUBLE PRECISION array, dimension KBOT */
/* On output, the real and imaginary parts of approximate */
/* eigenvalues that may be used for shifts are stored in */
/* SR(KBOT-ND-NS+1) through SR(KBOT-ND) and */
/* SI(KBOT-ND-NS+1) through SI(KBOT-ND), respectively. */
/* The real and imaginary parts of converged eigenvalues */
/* are stored in SR(KBOT-ND+1) through SR(KBOT) and */
/* SI(KBOT-ND+1) through SI(KBOT), respectively. */
/* V (workspace) DOUBLE PRECISION array, dimension (LDV,NW) */
/* An NW-by-NW work array. */
/* LDV (input) integer scalar */
/* The leading dimension of V just as declared in the */
/* calling subroutine. NW .LE. LDV */
/* NH (input) integer scalar */
/* The number of columns of T. NH.GE.NW. */
/* T (workspace) DOUBLE PRECISION array, dimension (LDT,NW) */
/* LDT (input) integer */
/* The leading dimension of T just as declared in the */
/* calling subroutine. NW .LE. LDT */
/* NV (input) integer */
/* The number of rows of work array WV available for */
/* workspace. NV.GE.NW. */
/* WV (workspace) DOUBLE PRECISION array, dimension (LDWV,NW) */
/* LDWV (input) integer */
/* The leading dimension of W just as declared in the */
/* calling subroutine. NW .LE. LDV */
/* WORK (workspace) DOUBLE PRECISION array, dimension LWORK. */
/* On exit, WORK(1) is set to an estimate of the optimal value */
/* of LWORK for the given values of N, NW, KTOP and KBOT. */
/* LWORK (input) integer */
/* The dimension of the work array WORK. LWORK = 2*NW */
/* suffices, but greater efficiency may result from larger */
/* values of LWORK. */
/* If LWORK = -1, then a workspace query is assumed; DLAQR2 */
/* only estimates the optimal workspace size for the given */
/* values of N, NW, KTOP and KBOT. The estimate is returned */
/* in WORK(1). No error message related to LWORK is issued */
/* by XERBLA. Neither H nor Z are accessed. */
/* ================================================================ */
/* Based on contributions by */
/* Karen Braman and Ralph Byers, Department of Mathematics, */
/* University of Kansas, USA */
/* ================================================================ */
/* .. Parameters .. */
/* .. */
/* .. Local Scalars .. */
/* .. */
/* .. External Functions .. */
/* .. */
/* .. External Subroutines .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* .. Executable Statements .. */
/* ==== Estimate optimal workspace. ==== */
/* Parameter adjustments */
h_dim1 = *ldh;
h_offset = 1 + h_dim1;
h__ -= h_offset;
z_dim1 = *ldz;
z_offset = 1 + z_dim1;
z__ -= z_offset;
--sr;
--si;
v_dim1 = *ldv;
v_offset = 1 + v_dim1;
v -= v_offset;
t_dim1 = *ldt;
t_offset = 1 + t_dim1;
t -= t_offset;
wv_dim1 = *ldwv;
wv_offset = 1 + wv_dim1;
wv -= wv_offset;
--work;
/* Function Body */
/* Computing MIN */
i__1 = *nw, i__2 = *kbot - *ktop + 1;
jw = min(i__1,i__2);
if (jw <= 2) {
lwkopt = 1;
} else {
/* ==== Workspace query call to DGEHRD ==== */
i__1 = jw - 1;
dgehrd_(&jw, &c__1, &i__1, &t[t_offset], ldt, &work[1], &work[1], &
c_n1, &info);
lwk1 = (integer) work[1];
/* ==== Workspace query call to DORGHR ==== */
i__1 = jw - 1;
dorghr_(&jw, &c__1, &i__1, &t[t_offset], ldt, &work[1], &work[1], &
c_n1, &info);
lwk2 = (integer) work[1];
/* ==== Optimal workspace ==== */
lwkopt = jw + max(lwk1,lwk2);
}
/* ==== Quick return in case of workspace query. ==== */
if (*lwork == -1) {
work[1] = (doublereal) lwkopt;
return 0;
}
/* ==== Nothing to do ... */
/* ... for an empty active block ... ==== */
*ns = 0;
*nd = 0;
if (*ktop > *kbot) {
return 0;
}
/* ... nor for an empty deflation window. ==== */
if (*nw < 1) {
return 0;
}
/* ==== Machine constants ==== */
safmin = dlamch_("SAFE MINIMUM");
safmax = 1. / safmin;
dlabad_(&safmin, &safmax);
ulp = dlamch_("PRECISION");
smlnum = safmin * ((doublereal) (*n) / ulp);
/* ==== Setup deflation window ==== */
/* Computing MIN */
i__1 = *nw, i__2 = *kbot - *ktop + 1;
jw = min(i__1,i__2);
kwtop = *kbot - jw + 1;
if (kwtop == *ktop) {
s = 0.;
} else {
s = h__[kwtop + (kwtop - 1) * h_dim1];
}
if (*kbot == kwtop) {
/* ==== 1-by-1 deflation window: not much to do ==== */
sr[kwtop] = h__[kwtop + kwtop * h_dim1];
si[kwtop] = 0.;
*ns = 1;
*nd = 0;
/* Computing MAX */
d__2 = smlnum, d__3 = ulp * (d__1 = h__[kwtop + kwtop * h_dim1], abs(
d__1));
if (abs(s) <= max(d__2,d__3)) {
*ns = 0;
*nd = 1;
if (kwtop > *ktop) {
h__[kwtop + (kwtop - 1) * h_dim1] = 0.;
}
}
return 0;
}
/* ==== Convert to spike-triangular form. (In case of a */
/* . rare QR failure, this routine continues to do */
/* . aggressive early deflation using that part of */
/* . the deflation window that converged using INFQR */
/* . here and there to keep track.) ==== */
dlacpy_("U", &jw, &jw, &h__[kwtop + kwtop * h_dim1], ldh, &t[t_offset],
ldt);
i__1 = jw - 1;
i__2 = *ldh + 1;
i__3 = *ldt + 1;
dcopy_(&i__1, &h__[kwtop + 1 + kwtop * h_dim1], &i__2, &t[t_dim1 + 2], &
i__3);
dlaset_("A", &jw, &jw, &c_b10, &c_b11, &v[v_offset], ldv);
dlahqr_(&c_true, &c_true, &jw, &c__1, &jw, &t[t_offset], ldt, &sr[kwtop],
&si[kwtop], &c__1, &jw, &v[v_offset], ldv, &infqr);
/* ==== DTREXC needs a clean margin near the diagonal ==== */
i__1 = jw - 3;
for (j = 1; j <= i__1; ++j) {
t[j + 2 + j * t_dim1] = 0.;
t[j + 3 + j * t_dim1] = 0.;
/* L10: */
}
if (jw > 2) {
t[jw + (jw - 2) * t_dim1] = 0.;
}
/* ==== Deflation detection loop ==== */
*ns = jw;
ilst = infqr + 1;
L20:
if (ilst <= *ns) {
if (*ns == 1) {
bulge = FALSE_;
} else {
bulge = t[*ns + (*ns - 1) * t_dim1] != 0.;
}
/* ==== Small spike tip test for deflation ==== */
if (! bulge) {
/* ==== Real eigenvalue ==== */
foo = (d__1 = t[*ns + *ns * t_dim1], abs(d__1));
if (foo == 0.) {
foo = abs(s);
}
/* Computing MAX */
d__2 = smlnum, d__3 = ulp * foo;
if ((d__1 = s * v[*ns * v_dim1 + 1], abs(d__1)) <= max(d__2,d__3))
{
/* ==== Deflatable ==== */
--(*ns);
} else {
/* ==== Undeflatable. Move it up out of the way. */
/* . (DTREXC can not fail in this case.) ==== */
ifst = *ns;
dtrexc_("V", &jw, &t[t_offset], ldt, &v[v_offset], ldv, &ifst,
&ilst, &work[1], &info);
++ilst;
}
} else {
/* ==== Complex conjugate pair ==== */
foo = (d__3 = t[*ns + *ns * t_dim1], abs(d__3)) + sqrt((d__1 = t[*
ns + (*ns - 1) * t_dim1], abs(d__1))) * sqrt((d__2 = t[*
ns - 1 + *ns * t_dim1], abs(d__2)));
if (foo == 0.) {
foo = abs(s);
}
/* Computing MAX */
d__3 = (d__1 = s * v[*ns * v_dim1 + 1], abs(d__1)), d__4 = (d__2 =
s * v[(*ns - 1) * v_dim1 + 1], abs(d__2));
/* Computing MAX */
d__5 = smlnum, d__6 = ulp * foo;
if (max(d__3,d__4) <= max(d__5,d__6)) {
/* ==== Deflatable ==== */
*ns += -2;
} else {
/* ==== Undflatable. Move them up out of the way. */
/* . Fortunately, DTREXC does the right thing with */
/* . ILST in case of a rare exchange failure. ==== */
ifst = *ns;
dtrexc_("V", &jw, &t[t_offset], ldt, &v[v_offset], ldv, &ifst,
&ilst, &work[1], &info);
ilst += 2;
}
}
/* ==== End deflation detection loop ==== */
goto L20;
}
/* ==== Return to Hessenberg form ==== */
if (*ns == 0) {
s = 0.;
}
if (*ns < jw) {
/* ==== sorting diagonal blocks of T improves accuracy for */
/* . graded matrices. Bubble sort deals well with */
/* . exchange failures. ==== */
sorted = FALSE_;
i__ = *ns + 1;
L30:
if (sorted) {
goto L50;
}
sorted = TRUE_;
kend = i__ - 1;
i__ = infqr + 1;
if (i__ == *ns) {
k = i__ + 1;
} else if (t[i__ + 1 + i__ * t_dim1] == 0.) {
k = i__ + 1;
} else {
k = i__ + 2;
}
L40:
if (k <= kend) {
if (k == i__ + 1) {
evi = (d__1 = t[i__ + i__ * t_dim1], abs(d__1));
} else {
evi = (d__3 = t[i__ + i__ * t_dim1], abs(d__3)) + sqrt((d__1 =
t[i__ + 1 + i__ * t_dim1], abs(d__1))) * sqrt((d__2 =
t[i__ + (i__ + 1) * t_dim1], abs(d__2)));
}
if (k == kend) {
evk = (d__1 = t[k + k * t_dim1], abs(d__1));
} else if (t[k + 1 + k * t_dim1] == 0.) {
evk = (d__1 = t[k + k * t_dim1], abs(d__1));
} else {
evk = (d__3 = t[k + k * t_dim1], abs(d__3)) + sqrt((d__1 = t[
k + 1 + k * t_dim1], abs(d__1))) * sqrt((d__2 = t[k +
(k + 1) * t_dim1], abs(d__2)));
}
if (evi >= evk) {
i__ = k;
} else {
sorted = FALSE_;
ifst = i__;
ilst = k;
dtrexc_("V", &jw, &t[t_offset], ldt, &v[v_offset], ldv, &ifst,
&ilst, &work[1], &info);
if (info == 0) {
i__ = ilst;
} else {
i__ = k;
}
}
if (i__ == kend) {
k = i__ + 1;
} else if (t[i__ + 1 + i__ * t_dim1] == 0.) {
k = i__ + 1;
} else {
k = i__ + 2;
}
goto L40;
}
goto L30;
L50:
;
}
/* ==== Restore shift/eigenvalue array from T ==== */
i__ = jw;
L60:
if (i__ >= infqr + 1) {
if (i__ == infqr + 1) {
sr[kwtop + i__ - 1] = t[i__ + i__ * t_dim1];
si[kwtop + i__ - 1] = 0.;
--i__;
} else if (t[i__ + (i__ - 1) * t_dim1] == 0.) {
sr[kwtop + i__ - 1] = t[i__ + i__ * t_dim1];
si[kwtop + i__ - 1] = 0.;
--i__;
} else {
aa = t[i__ - 1 + (i__ - 1) * t_dim1];
cc = t[i__ + (i__ - 1) * t_dim1];
bb = t[i__ - 1 + i__ * t_dim1];
dd = t[i__ + i__ * t_dim1];
dlanv2_(&aa, &bb, &cc, &dd, &sr[kwtop + i__ - 2], &si[kwtop + i__
- 2], &sr[kwtop + i__ - 1], &si[kwtop + i__ - 1], &cs, &
sn);
i__ += -2;
}
goto L60;
}
if (*ns < jw || s == 0.) {
if (*ns > 1 && s != 0.) {
/* ==== Reflect spike back into lower triangle ==== */
dcopy_(ns, &v[v_offset], ldv, &work[1], &c__1);
beta = work[1];
dlarfg_(ns, &beta, &work[2], &c__1, &tau);
work[1] = 1.;
i__1 = jw - 2;
i__2 = jw - 2;
dlaset_("L", &i__1, &i__2, &c_b10, &c_b10, &t[t_dim1 + 3], ldt);
dlarf_("L", ns, &jw, &work[1], &c__1, &tau, &t[t_offset], ldt, &
work[jw + 1]);
dlarf_("R", ns, ns, &work[1], &c__1, &tau, &t[t_offset], ldt, &
work[jw + 1]);
dlarf_("R", &jw, ns, &work[1], &c__1, &tau, &v[v_offset], ldv, &
work[jw + 1]);
i__1 = *lwork - jw;
dgehrd_(&jw, &c__1, ns, &t[t_offset], ldt, &work[1], &work[jw + 1]
, &i__1, &info);
}
/* ==== Copy updated reduced window into place ==== */
if (kwtop > 1) {
h__[kwtop + (kwtop - 1) * h_dim1] = s * v[v_dim1 + 1];
}
dlacpy_("U", &jw, &jw, &t[t_offset], ldt, &h__[kwtop + kwtop * h_dim1]
, ldh);
i__1 = jw - 1;
i__2 = *ldt + 1;
i__3 = *ldh + 1;
dcopy_(&i__1, &t[t_dim1 + 2], &i__2, &h__[kwtop + 1 + kwtop * h_dim1],
&i__3);
/* ==== Accumulate orthogonal matrix in order update */
/* . H and Z, if requested. (A modified version */
/* . of DORGHR that accumulates block Householder */
/* . transformations into V directly might be */
/* . marginally more efficient than the following.) ==== */
if (*ns > 1 && s != 0.) {
i__1 = *lwork - jw;
dorghr_(&jw, &c__1, ns, &t[t_offset], ldt, &work[1], &work[jw + 1]
, &i__1, &info);
dgemm_("N", "N", &jw, ns, ns, &c_b11, &v[v_offset], ldv, &t[
t_offset], ldt, &c_b10, &wv[wv_offset], ldwv);
dlacpy_("A", &jw, ns, &wv[wv_offset], ldwv, &v[v_offset], ldv);
}
/* ==== Update vertical slab in H ==== */
if (*wantt) {
ltop = 1;
} else {
ltop = *ktop;
}
i__1 = kwtop - 1;
i__2 = *nv;
for (krow = ltop; i__2 < 0 ? krow >= i__1 : krow <= i__1; krow +=
i__2) {
/* Computing MIN */
i__3 = *nv, i__4 = kwtop - krow;
kln = min(i__3,i__4);
dgemm_("N", "N", &kln, &jw, &jw, &c_b11, &h__[krow + kwtop *
h_dim1], ldh, &v[v_offset], ldv, &c_b10, &wv[wv_offset],
ldwv);
dlacpy_("A", &kln, &jw, &wv[wv_offset], ldwv, &h__[krow + kwtop *
h_dim1], ldh);
/* L70: */
}
/* ==== Update horizontal slab in H ==== */
if (*wantt) {
i__2 = *n;
i__1 = *nh;
for (kcol = *kbot + 1; i__1 < 0 ? kcol >= i__2 : kcol <= i__2;
kcol += i__1) {
/* Computing MIN */
i__3 = *nh, i__4 = *n - kcol + 1;
kln = min(i__3,i__4);
dgemm_("C", "N", &jw, &kln, &jw, &c_b11, &v[v_offset], ldv, &
h__[kwtop + kcol * h_dim1], ldh, &c_b10, &t[t_offset],
ldt);
dlacpy_("A", &jw, &kln, &t[t_offset], ldt, &h__[kwtop + kcol *
h_dim1], ldh);
/* L80: */
}
}
/* ==== Update vertical slab in Z ==== */
if (*wantz) {
i__1 = *ihiz;
i__2 = *nv;
for (krow = *iloz; i__2 < 0 ? krow >= i__1 : krow <= i__1; krow +=
i__2) {
/* Computing MIN */
i__3 = *nv, i__4 = *ihiz - krow + 1;
kln = min(i__3,i__4);
dgemm_("N", "N", &kln, &jw, &jw, &c_b11, &z__[krow + kwtop *
z_dim1], ldz, &v[v_offset], ldv, &c_b10, &wv[
wv_offset], ldwv);
dlacpy_("A", &kln, &jw, &wv[wv_offset], ldwv, &z__[krow +
kwtop * z_dim1], ldz);
/* L90: */
}
}
}
/* ==== Return the number of deflations ... ==== */
*nd = jw - *ns;
/* ==== ... and the number of shifts. (Subtracting */
/* . INFQR from the spike length takes care */
/* . of the case of a rare QR failure while */
/* . calculating eigenvalues of the deflation */
/* . window.) ==== */
*ns -= infqr;
/* ==== Return optimal workspace. ==== */
work[1] = (doublereal) lwkopt;
/* ==== End of DLAQR2 ==== */
return 0;
} /* dlaqr2_ */
/* Subroutine */
int dtrsna_(char *job, char *howmny, logical *select, integer *n, doublereal *t, integer *ldt, doublereal *vl, integer * ldvl, doublereal *vr, integer *ldvr, doublereal *s, doublereal *sep, integer *mm, integer *m, doublereal *work, integer *ldwork, integer * iwork, integer *info)
{
/* System generated locals */
integer t_dim1, t_offset, vl_dim1, vl_offset, vr_dim1, vr_offset, work_dim1, work_offset, i__1, i__2;
doublereal d__1, d__2;
/* Builtin functions */
double sqrt(doublereal);
/* Local variables */
integer i__, j, k, n2;
doublereal cs;
integer nn, ks;
doublereal sn, mu, eps, est;
integer kase;
doublereal cond;
extern doublereal ddot_(integer *, doublereal *, integer *, doublereal *, integer *);
logical pair;
integer ierr;
doublereal dumm, prod;
integer ifst;
doublereal lnrm;
integer ilst;
doublereal rnrm;
extern doublereal dnrm2_(integer *, doublereal *, integer *);
doublereal prod1, prod2, scale, delta;
extern logical lsame_(char *, char *);
integer isave[3];
logical wants;
doublereal dummy[1];
extern /* Subroutine */
int dlacn2_(integer *, doublereal *, doublereal *, integer *, doublereal *, integer *, integer *);
extern doublereal dlapy2_(doublereal *, doublereal *);
extern /* Subroutine */
int dlabad_(doublereal *, doublereal *);
extern doublereal dlamch_(char *);
extern /* Subroutine */
int dlacpy_(char *, integer *, integer *, doublereal *, integer *, doublereal *, integer *), xerbla_(char *, integer *);
doublereal bignum;
logical wantbh;
extern /* Subroutine */
int dlaqtr_(logical *, logical *, integer *, doublereal *, integer *, doublereal *, doublereal *, doublereal *, doublereal *, doublereal *, integer *), dtrexc_(char *, integer * , doublereal *, integer *, doublereal *, integer *, integer *, integer *, doublereal *, integer *);
logical somcon;
doublereal smlnum;
logical wantsp;
/* -- LAPACK computational routine (version 3.4.0) -- */
/* -- LAPACK is a software package provided by Univ. of Tennessee, -- */
/* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- */
/* November 2011 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* ===================================================================== */
/* .. Parameters .. */
/* .. */
/* .. Local Scalars .. */
/* .. */
/* .. Local Arrays .. */
/* .. */
/* .. External Functions .. */
/* .. */
/* .. External Subroutines .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* .. Executable Statements .. */
/* Decode and test the input parameters */
/* Parameter adjustments */
--select;
t_dim1 = *ldt;
t_offset = 1 + t_dim1;
t -= t_offset;
vl_dim1 = *ldvl;
vl_offset = 1 + vl_dim1;
vl -= vl_offset;
vr_dim1 = *ldvr;
vr_offset = 1 + vr_dim1;
vr -= vr_offset;
--s;
--sep;
work_dim1 = *ldwork;
work_offset = 1 + work_dim1;
work -= work_offset;
--iwork;
/* Function Body */
wantbh = lsame_(job, "B");
wants = lsame_(job, "E") || wantbh;
wantsp = lsame_(job, "V") || wantbh;
somcon = lsame_(howmny, "S");
*info = 0;
if (! wants && ! wantsp)
{
*info = -1;
}
else if (! lsame_(howmny, "A") && ! somcon)
{
*info = -2;
}
else if (*n < 0)
{
*info = -4;
}
else if (*ldt < max(1,*n))
{
*info = -6;
}
else if (*ldvl < 1 || wants && *ldvl < *n)
{
*info = -8;
}
else if (*ldvr < 1 || wants && *ldvr < *n)
{
*info = -10;
}
else
{
/* Set M to the number of eigenpairs for which condition numbers */
/* are required, and test MM. */
if (somcon)
{
*m = 0;
pair = FALSE_;
i__1 = *n;
for (k = 1;
k <= i__1;
++k)
{
if (pair)
{
pair = FALSE_;
}
else
{
if (k < *n)
{
if (t[k + 1 + k * t_dim1] == 0.)
{
if (select[k])
{
++(*m);
}
}
else
{
pair = TRUE_;
if (select[k] || select[k + 1])
{
*m += 2;
}
}
}
else
{
if (select[*n])
{
++(*m);
}
}
}
/* L10: */
}
}
else
{
*m = *n;
}
if (*mm < *m)
{
*info = -13;
}
else if (*ldwork < 1 || wantsp && *ldwork < *n)
{
*info = -16;
}
}
if (*info != 0)
{
i__1 = -(*info);
xerbla_("DTRSNA", &i__1);
return 0;
}
/* Quick return if possible */
if (*n == 0)
{
return 0;
}
if (*n == 1)
{
if (somcon)
{
if (! select[1])
{
return 0;
}
}
if (wants)
{
s[1] = 1.;
}
if (wantsp)
{
sep[1] = (d__1 = t[t_dim1 + 1], abs(d__1));
}
return 0;
}
/* Get machine constants */
eps = dlamch_("P");
smlnum = dlamch_("S") / eps;
bignum = 1. / smlnum;
dlabad_(&smlnum, &bignum);
ks = 0;
pair = FALSE_;
i__1 = *n;
for (k = 1;
k <= i__1;
++k)
{
/* Determine whether T(k,k) begins a 1-by-1 or 2-by-2 block. */
if (pair)
{
pair = FALSE_;
goto L60;
}
else
{
if (k < *n)
{
pair = t[k + 1 + k * t_dim1] != 0.;
}
}
/* Determine whether condition numbers are required for the k-th */
/* eigenpair. */
if (somcon)
{
if (pair)
{
if (! select[k] && ! select[k + 1])
{
goto L60;
}
}
else
{
if (! select[k])
{
goto L60;
}
}
}
++ks;
if (wants)
{
/* Compute the reciprocal condition number of the k-th */
/* eigenvalue. */
if (! pair)
{
/* Real eigenvalue. */
prod = ddot_(n, &vr[ks * vr_dim1 + 1], &c__1, &vl[ks * vl_dim1 + 1], &c__1);
rnrm = dnrm2_(n, &vr[ks * vr_dim1 + 1], &c__1);
lnrm = dnrm2_(n, &vl[ks * vl_dim1 + 1], &c__1);
s[ks] = abs(prod) / (rnrm * lnrm);
}
else
{
/* Complex eigenvalue. */
prod1 = ddot_(n, &vr[ks * vr_dim1 + 1], &c__1, &vl[ks * vl_dim1 + 1], &c__1);
prod1 += ddot_(n, &vr[(ks + 1) * vr_dim1 + 1], &c__1, &vl[(ks + 1) * vl_dim1 + 1], &c__1);
prod2 = ddot_(n, &vl[ks * vl_dim1 + 1], &c__1, &vr[(ks + 1) * vr_dim1 + 1], &c__1);
prod2 -= ddot_(n, &vl[(ks + 1) * vl_dim1 + 1], &c__1, &vr[ks * vr_dim1 + 1], &c__1);
d__1 = dnrm2_(n, &vr[ks * vr_dim1 + 1], &c__1);
d__2 = dnrm2_(n, &vr[(ks + 1) * vr_dim1 + 1], &c__1);
rnrm = dlapy2_(&d__1, &d__2);
d__1 = dnrm2_(n, &vl[ks * vl_dim1 + 1], &c__1);
d__2 = dnrm2_(n, &vl[(ks + 1) * vl_dim1 + 1], &c__1);
lnrm = dlapy2_(&d__1, &d__2);
cond = dlapy2_(&prod1, &prod2) / (rnrm * lnrm);
s[ks] = cond;
s[ks + 1] = cond;
}
}
if (wantsp)
{
/* Estimate the reciprocal condition number of the k-th */
/* eigenvector. */
/* Copy the matrix T to the array WORK and swap the diagonal */
/* block beginning at T(k,k) to the (1,1) position. */
dlacpy_("Full", n, n, &t[t_offset], ldt, &work[work_offset], ldwork);
ifst = k;
ilst = 1;
dtrexc_("No Q", n, &work[work_offset], ldwork, dummy, &c__1, & ifst, &ilst, &work[(*n + 1) * work_dim1 + 1], &ierr);
if (ierr == 1 || ierr == 2)
{
/* Could not swap because blocks not well separated */
scale = 1.;
est = bignum;
}
else
{
/* Reordering successful */
if (work[work_dim1 + 2] == 0.)
{
/* Form C = T22 - lambda*I in WORK(2:N,2:N). */
i__2 = *n;
for (i__ = 2;
i__ <= i__2;
++i__)
{
work[i__ + i__ * work_dim1] -= work[work_dim1 + 1];
/* L20: */
}
n2 = 1;
nn = *n - 1;
}
else
{
/* Triangularize the 2 by 2 block by unitary */
/* transformation U = [ cs i*ss ] */
/* [ i*ss cs ]. */
/* such that the (1,1) position of WORK is complex */
/* eigenvalue lambda with positive imaginary part. (2,2) */
/* position of WORK is the complex eigenvalue lambda */
/* with negative imaginary part. */
mu = sqrt((d__1 = work[(work_dim1 << 1) + 1], abs(d__1))) * sqrt((d__2 = work[work_dim1 + 2], abs(d__2)));
delta = dlapy2_(&mu, &work[work_dim1 + 2]);
cs = mu / delta;
sn = -work[work_dim1 + 2] / delta;
/* Form */
/* C**T = WORK(2:N,2:N) + i*[rwork(1) ..... rwork(n-1) ] */
/* [ mu ] */
/* [ .. ] */
/* [ .. ] */
/* [ mu ] */
/* where C**T is transpose of matrix C, */
/* and RWORK is stored starting in the N+1-st column of */
/* WORK. */
i__2 = *n;
for (j = 3;
j <= i__2;
++j)
{
work[j * work_dim1 + 2] = cs * work[j * work_dim1 + 2] ;
work[j + j * work_dim1] -= work[work_dim1 + 1];
/* L30: */
}
work[(work_dim1 << 1) + 2] = 0.;
work[(*n + 1) * work_dim1 + 1] = mu * 2.;
i__2 = *n - 1;
for (i__ = 2;
i__ <= i__2;
++i__)
{
work[i__ + (*n + 1) * work_dim1] = sn * work[(i__ + 1) * work_dim1 + 1];
/* L40: */
}
n2 = 2;
nn = *n - 1 << 1;
}
/* Estimate norm(inv(C**T)) */
est = 0.;
kase = 0;
L50:
dlacn2_(&nn, &work[(*n + 2) * work_dim1 + 1], &work[(*n + 4) * work_dim1 + 1], &iwork[1], &est, &kase, isave);
if (kase != 0)
{
if (kase == 1)
{
if (n2 == 1)
{
/* Real eigenvalue: solve C**T*x = scale*c. */
i__2 = *n - 1;
dlaqtr_(&c_true, &c_true, &i__2, &work[(work_dim1 << 1) + 2], ldwork, dummy, &dumm, &scale, &work[(*n + 4) * work_dim1 + 1], &work[(* n + 6) * work_dim1 + 1], &ierr);
}
else
{
/* Complex eigenvalue: solve */
/* C**T*(p+iq) = scale*(c+id) in real arithmetic. */
i__2 = *n - 1;
dlaqtr_(&c_true, &c_false, &i__2, &work[( work_dim1 << 1) + 2], ldwork, &work[(*n + 1) * work_dim1 + 1], &mu, &scale, &work[(* n + 4) * work_dim1 + 1], &work[(*n + 6) * work_dim1 + 1], &ierr);
}
}
else
{
if (n2 == 1)
{
/* Real eigenvalue: solve C*x = scale*c. */
i__2 = *n - 1;
dlaqtr_(&c_false, &c_true, &i__2, &work[( work_dim1 << 1) + 2], ldwork, dummy, & dumm, &scale, &work[(*n + 4) * work_dim1 + 1], &work[(*n + 6) * work_dim1 + 1], & ierr);
}
else
{
/* Complex eigenvalue: solve */
/* C*(p+iq) = scale*(c+id) in real arithmetic. */
i__2 = *n - 1;
dlaqtr_(&c_false, &c_false, &i__2, &work[( work_dim1 << 1) + 2], ldwork, &work[(*n + 1) * work_dim1 + 1], &mu, &scale, &work[(* n + 4) * work_dim1 + 1], &work[(*n + 6) * work_dim1 + 1], &ierr);
}
}
goto L50;
}
}
sep[ks] = scale / max(est,smlnum);
if (pair)
{
sep[ks + 1] = sep[ks];
}
}
if (pair)
{
++ks;
}
L60:
;
}
return 0;
/* End of DTRSNA */
}
/* Subroutine */ int dtrsna_(char *job, char *howmny, logical *select,
integer *n, doublereal *t, integer *ldt, doublereal *vl, integer *
ldvl, doublereal *vr, integer *ldvr, doublereal *s, doublereal *sep,
integer *mm, integer *m, doublereal *work, integer *ldwork, integer *
iwork, integer *info)
{
/* -- LAPACK routine (version 2.0) --
Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,
Courant Institute, Argonne National Lab, and Rice University
September 30, 1994
Purpose
=======
DTRSNA estimates reciprocal condition numbers for specified
eigenvalues and/or right eigenvectors of a real upper
quasi-triangular matrix T (or of any matrix Q*T*Q**T with Q
orthogonal).
T must be in Schur canonical form (as returned by DHSEQR), that is,
block upper triangular with 1-by-1 and 2-by-2 diagonal blocks; each
2-by-2 diagonal block has its diagonal elements equal and its
off-diagonal elements of opposite sign.
Arguments
=========
JOB (input) CHARACTER*1
Specifies whether condition numbers are required for
eigenvalues (S) or eigenvectors (SEP):
= 'E': for eigenvalues only (S);
= 'V': for eigenvectors only (SEP);
= 'B': for both eigenvalues and eigenvectors (S and SEP).
HOWMNY (input) CHARACTER*1
= 'A': compute condition numbers for all eigenpairs;
= 'S': compute condition numbers for selected eigenpairs
specified by the array SELECT.
SELECT (input) LOGICAL array, dimension (N)
If HOWMNY = 'S', SELECT specifies the eigenpairs for which
condition numbers are required. To select condition numbers
for the eigenpair corresponding to a real eigenvalue w(j),
SELECT(j) must be set to .TRUE.. To select condition numbers
corresponding to a complex conjugate pair of eigenvalues w(j)
and w(j+1), either SELECT(j) or SELECT(j+1) or both, must be
set to .TRUE..
If HOWMNY = 'A', SELECT is not referenced.
N (input) INTEGER
The order of the matrix T. N >= 0.
T (input) DOUBLE PRECISION array, dimension (LDT,N)
The upper quasi-triangular matrix T, in Schur canonical form.
LDT (input) INTEGER
The leading dimension of the array T. LDT >= max(1,N).
VL (input) DOUBLE PRECISION array, dimension (LDVL,M)
If JOB = 'E' or 'B', VL must contain left eigenvectors of T
(or of any Q*T*Q**T with Q orthogonal), corresponding to the
eigenpairs specified by HOWMNY and SELECT. The eigenvectors
must be stored in consecutive columns of VL, as returned by
DHSEIN or DTREVC.
If JOB = 'V', VL is not referenced.
LDVL (input) INTEGER
The leading dimension of the array VL.
LDVL >= 1; and if JOB = 'E' or 'B', LDVL >= N.
VR (input) DOUBLE PRECISION array, dimension (LDVR,M)
If JOB = 'E' or 'B', VR must contain right eigenvectors of T
(or of any Q*T*Q**T with Q orthogonal), corresponding to the
eigenpairs specified by HOWMNY and SELECT. The eigenvectors
must be stored in consecutive columns of VR, as returned by
DHSEIN or DTREVC.
If JOB = 'V', VR is not referenced.
LDVR (input) INTEGER
The leading dimension of the array VR.
LDVR >= 1; and if JOB = 'E' or 'B', LDVR >= N.
S (output) DOUBLE PRECISION array, dimension (MM)
If JOB = 'E' or 'B', the reciprocal condition numbers of the
selected eigenvalues, stored in consecutive elements of the
array. For a complex conjugate pair of eigenvalues two
consecutive elements of S are set to the same value. Thus
S(j), SEP(j), and the j-th columns of VL and VR all
correspond to the same eigenpair (but not in general the
j-th eigenpair, unless all eigenpairs are selected).
If JOB = 'V', S is not referenced.
SEP (output) DOUBLE PRECISION array, dimension (MM)
If JOB = 'V' or 'B', the estimated reciprocal condition
numbers of the selected eigenvectors, stored in consecutive
elements of the array. For a complex eigenvector two
consecutive elements of SEP are set to the same value. If
the eigenvalues cannot be reordered to compute SEP(j), SEP(j)
is set to 0; this can only occur when the true value would be
very small anyway.
If JOB = 'E', SEP is not referenced.
MM (input) INTEGER
The number of elements in the arrays S (if JOB = 'E' or 'B')
and/or SEP (if JOB = 'V' or 'B'). MM >= M.
M (output) INTEGER
The number of elements of the arrays S and/or SEP actually
used to store the estimated condition numbers.
If HOWMNY = 'A', M is set to N.
WORK (workspace) DOUBLE PRECISION array, dimension (LDWORK,N+1)
If JOB = 'E', WORK is not referenced.
LDWORK (input) INTEGER
The leading dimension of the array WORK.
LDWORK >= 1; and if JOB = 'V' or 'B', LDWORK >= N.
IWORK (workspace) INTEGER array, dimension (N)
If JOB = 'E', IWORK is not referenced.
INFO (output) INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
Further Details
===============
The reciprocal of the condition number of an eigenvalue lambda is
defined as
S(lambda) = |v'*u| / (norm(u)*norm(v))
where u and v are the right and left eigenvectors of T corresponding
to lambda; v' denotes the conjugate-transpose of v, and norm(u)
denotes the Euclidean norm. These reciprocal condition numbers always
lie between zero (very badly conditioned) and one (very well
conditioned). If n = 1, S(lambda) is defined to be 1.
An approximate error bound for a computed eigenvalue W(i) is given by
EPS * norm(T) / S(i)
where EPS is the machine precision.
The reciprocal of the condition number of the right eigenvector u
corresponding to lambda is defined as follows. Suppose
T = ( lambda c )
( 0 T22 )
Then the reciprocal condition number is
SEP( lambda, T22 ) = sigma-min( T22 - lambda*I )
where sigma-min denotes the smallest singular value. We approximate
the smallest singular value by the reciprocal of an estimate of the
one-norm of the inverse of T22 - lambda*I. If n = 1, SEP(1) is
defined to be abs(T(1,1)).
An approximate error bound for a computed right eigenvector VR(i)
is given by
EPS * norm(T) / SEP(i)
=====================================================================
Decode and test the input parameters
Parameter adjustments
Function Body */
/* Table of constant values */
static integer c__1 = 1;
static logical c_true = TRUE_;
static logical c_false = FALSE_;
/* System generated locals */
integer t_dim1, t_offset, vl_dim1, vl_offset, vr_dim1, vr_offset,
work_dim1, work_offset, i__1, i__2;
doublereal d__1, d__2;
/* Builtin functions */
double sqrt(doublereal);
/* Local variables */
static integer kase;
static doublereal cond;
extern doublereal ddot_(integer *, doublereal *, integer *, doublereal *,
integer *);
static logical pair;
static integer ierr;
static doublereal dumm, prod;
static integer ifst;
static doublereal lnrm;
static integer ilst;
static doublereal rnrm;
extern doublereal dnrm2_(integer *, doublereal *, integer *);
static doublereal prod1, prod2;
static integer i, j, k;
static doublereal scale, delta;
extern logical lsame_(char *, char *);
static logical wants;
static doublereal dummy[1];
static integer n2;
extern doublereal dlapy2_(doublereal *, doublereal *);
extern /* Subroutine */ int dlabad_(doublereal *, doublereal *);
static doublereal cs;
extern doublereal dlamch_(char *);
static integer nn, ks;
extern /* Subroutine */ int dlacon_(integer *, doublereal *, doublereal *,
integer *, doublereal *, integer *);
static doublereal sn, mu;
extern /* Subroutine */ int dlacpy_(char *, integer *, integer *,
doublereal *, integer *, doublereal *, integer *),
xerbla_(char *, integer *);
static doublereal bignum;
static logical wantbh;
extern /* Subroutine */ int dlaqtr_(logical *, logical *, integer *,
doublereal *, integer *, doublereal *, doublereal *, doublereal *,
doublereal *, doublereal *, integer *), dtrexc_(char *, integer *
, doublereal *, integer *, doublereal *, integer *, integer *,
integer *, doublereal *, integer *);
static logical somcon;
static doublereal smlnum;
static logical wantsp;
static doublereal eps, est;
#define DUMMY(I) dummy[(I)]
#define SELECT(I) select[(I)-1]
#define S(I) s[(I)-1]
#define SEP(I) sep[(I)-1]
#define IWORK(I) iwork[(I)-1]
#define T(I,J) t[(I)-1 + ((J)-1)* ( *ldt)]
#define VL(I,J) vl[(I)-1 + ((J)-1)* ( *ldvl)]
#define VR(I,J) vr[(I)-1 + ((J)-1)* ( *ldvr)]
#define WORK(I,J) work[(I)-1 + ((J)-1)* ( *ldwork)]
wantbh = lsame_(job, "B");
wants = lsame_(job, "E") || wantbh;
wantsp = lsame_(job, "V") || wantbh;
somcon = lsame_(howmny, "S");
*info = 0;
if (! wants && ! wantsp) {
*info = -1;
} else if (! lsame_(howmny, "A") && ! somcon) {
*info = -2;
} else if (*n < 0) {
*info = -4;
} else if (*ldt < max(1,*n)) {
*info = -6;
} else if (*ldvl < 1 || wants && *ldvl < *n) {
*info = -8;
} else if (*ldvr < 1 || wants && *ldvr < *n) {
*info = -10;
} else {
/* Set M to the number of eigenpairs for which condition number
s
are required, and test MM. */
if (somcon) {
*m = 0;
pair = FALSE_;
i__1 = *n;
for (k = 1; k <= *n; ++k) {
if (pair) {
pair = FALSE_;
} else {
if (k < *n) {
if (T(k+1,k) == 0.) {
if (SELECT(k)) {
++(*m);
}
} else {
pair = TRUE_;
if (SELECT(k) || SELECT(k + 1)) {
*m += 2;
}
}
} else {
if (SELECT(*n)) {
++(*m);
}
}
}
/* L10: */
}
} else {
*m = *n;
}
if (*mm < *m) {
*info = -13;
} else if (*ldwork < 1 || wantsp && *ldwork < *n) {
*info = -16;
}
}
if (*info != 0) {
i__1 = -(*info);
xerbla_("DTRSNA", &i__1);
return 0;
}
/* Quick return if possible */
if (*n == 0) {
return 0;
}
if (*n == 1) {
if (somcon) {
if (! SELECT(1)) {
return 0;
}
}
if (wants) {
S(1) = 1.;
}
if (wantsp) {
SEP(1) = (d__1 = T(1,1), abs(d__1));
}
return 0;
}
/* Get machine constants */
eps = dlamch_("P");
smlnum = dlamch_("S") / eps;
bignum = 1. / smlnum;
dlabad_(&smlnum, &bignum);
ks = 0;
pair = FALSE_;
i__1 = *n;
for (k = 1; k <= *n; ++k) {
/* Determine whether T(k,k) begins a 1-by-1 or 2-by-2 block. */
if (pair) {
pair = FALSE_;
goto L60;
} else {
if (k < *n) {
pair = T(k+1,k) != 0.;
}
}
/* Determine whether condition numbers are required for the k-t
h
eigenpair. */
if (somcon) {
if (pair) {
if (! SELECT(k) && ! SELECT(k + 1)) {
goto L60;
}
} else {
if (! SELECT(k)) {
goto L60;
}
}
}
++ks;
if (wants) {
/* Compute the reciprocal condition number of the k-th
eigenvalue. */
if (! pair) {
/* Real eigenvalue. */
prod = ddot_(n, &VR(1,ks), &c__1, &VL(1,ks), &c__1);
rnrm = dnrm2_(n, &VR(1,ks), &c__1);
lnrm = dnrm2_(n, &VL(1,ks), &c__1);
S(ks) = abs(prod) / (rnrm * lnrm);
} else {
/* Complex eigenvalue. */
prod1 = ddot_(n, &VR(1,ks), &c__1, &VL(1,ks), &c__1);
prod1 += ddot_(n, &VR(1,ks+1), &c__1, &VL(1,ks+1), &c__1);
prod2 = ddot_(n, &VL(1,ks), &c__1, &VR(1,ks+1), &c__1);
prod2 -= ddot_(n, &VL(1,ks+1), &c__1, &VR(1,ks), &c__1);
d__1 = dnrm2_(n, &VR(1,ks), &c__1);
d__2 = dnrm2_(n, &VR(1,ks+1), &c__1);
rnrm = dlapy2_(&d__1, &d__2);
d__1 = dnrm2_(n, &VL(1,ks), &c__1);
d__2 = dnrm2_(n, &VL(1,ks+1), &c__1);
lnrm = dlapy2_(&d__1, &d__2);
cond = dlapy2_(&prod1, &prod2) / (rnrm * lnrm);
S(ks) = cond;
S(ks + 1) = cond;
}
}
if (wantsp) {
/* Estimate the reciprocal condition number of the k-th
eigenvector.
Copy the matrix T to the array WORK and swap the diag
onal
block beginning at T(k,k) to the (1,1) position. */
dlacpy_("Full", n, n, &T(1,1), ldt, &WORK(1,1),
ldwork);
ifst = k;
ilst = 1;
dtrexc_("No Q", n, &WORK(1,1), ldwork, dummy, &c__1, &
ifst, &ilst, &WORK(1,*n+1), &ierr);
if (ierr == 1 || ierr == 2) {
/* Could not swap because blocks not well separat
ed */
scale = 1.;
est = bignum;
} else {
/* Reordering successful */
if (WORK(2,1) == 0.) {
/* Form C = T22 - lambda*I in WORK(2:N,2:N
). */
i__2 = *n;
for (i = 2; i <= *n; ++i) {
WORK(i,i) -= WORK(1,1);
/* L20: */
}
n2 = 1;
nn = *n - 1;
} else {
/* Triangularize the 2 by 2 block by unita
ry
transformation U = [ cs i*ss ]
[ i*ss cs ].
such that the (1,1) position of WORK is
complex
eigenvalue lambda with positive imagina
ry part. (2,2)
position of WORK is the complex eigenva
lue lambda
with negative imaginary part. */
mu = sqrt((d__1 = WORK(1,2), abs(d__1)))
* sqrt((d__2 = WORK(2,1), abs(d__2)));
delta = dlapy2_(&mu, &WORK(2,1));
cs = mu / delta;
sn = -WORK(2,1) / delta;
/* Form
C' = WORK(2:N,2:N) + i*[rwork(1) .....
rwork(n-1) ]
[ mu
]
[ ..
]
[ ..
]
[
mu ]
where C' is conjugate transpose of comp
lex matrix C,
and RWORK is stored starting in the N+1
-st column of
WORK. */
i__2 = *n;
for (j = 3; j <= *n; ++j) {
WORK(2,j) = cs * WORK(2,j)
;
WORK(j,j) -= WORK(1,1);
/* L30: */
}
WORK(2,2) = 0.;
WORK(1,*n+1) = mu * 2.;
i__2 = *n - 1;
for (i = 2; i <= *n-1; ++i) {
WORK(i,*n+1) = sn * WORK(1,i+1);
/* L40: */
}
n2 = 2;
nn = *n - 1 << 1;
}
/* Estimate norm(inv(C')) */
est = 0.;
kase = 0;
L50:
dlacon_(&nn, &WORK(1,*n+2), &WORK(1,*n+4), &IWORK(1), &est, &kase);
if (kase != 0) {
if (kase == 1) {
if (n2 == 1) {
/* Real eigenvalue: solve C'
*x = scale*c. */
i__2 = *n - 1;
dlaqtr_(&c_true, &c_true, &i__2, &WORK(2,2), ldwork, dummy, &dumm, &scale,
&WORK(1,*n+4), &WORK(1,*n+6), &ierr);
} else {
/* Complex eigenvalue: solve
C'*(p+iq) = scale*(c+id)
in real arithmetic. */
i__2 = *n - 1;
dlaqtr_(&c_true, &c_false, &i__2, &WORK(2,2), ldwork, &WORK(1,*n+1), &mu, &scale, &WORK(1,*n+4), &WORK(1,*n+6), &ierr);
}
} else {
if (n2 == 1) {
/* Real eigenvalue: solve C*
x = scale*c. */
i__2 = *n - 1;
dlaqtr_(&c_false, &c_true, &i__2, &WORK(2,2), ldwork, dummy, &
dumm, &scale, &WORK(1,*n+4), &WORK(1,*n+6), &
ierr);
} else {
/* Complex eigenvalue: solve
C*(p+iq) = scale*(c+id) i
n real arithmetic. */
i__2 = *n - 1;
dlaqtr_(&c_false, &c_false, &i__2, &WORK(2,2), ldwork, &WORK(1,*n+1), &mu, &scale, &WORK(1,*n+4), &WORK(1,*n+6), &ierr);
}
}
goto L50;
}
}
SEP(ks) = scale / max(est,smlnum);
if (pair) {
SEP(ks + 1) = SEP(ks);
}
}
if (pair) {
++ks;
}
L60:
;
}
return 0;
/* End of DTRSNA */
} /* dtrsna_ */
