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/* chsein.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"
/* Table of constant values */
static logical c_false = FALSE_;
static logical c_true = TRUE_;
/* Subroutine */ int chsein_(char *side, char *eigsrc, char *initv, logical *
select, integer *n, complex *h__, integer *ldh, complex *w, complex *
vl, integer *ldvl, complex *vr, integer *ldvr, integer *mm, integer *
m, complex *work, real *rwork, integer *ifaill, integer *ifailr,
integer *info)
{
/* System generated locals */
integer h_dim1, h_offset, vl_dim1, vl_offset, vr_dim1, vr_offset, i__1,
i__2, i__3;
real r__1, r__2;
complex q__1, q__2;
/* Builtin functions */
double r_imag(complex *);
/* Local variables */
integer i__, k, kl, kr, ks;
complex wk;
integer kln;
real ulp, eps3, unfl;
extern logical lsame_(char *, char *);
integer iinfo;
logical leftv, bothv;
real hnorm;
extern /* Subroutine */ int claein_(logical *, logical *, integer *,
complex *, integer *, complex *, complex *, complex *, integer *,
real *, real *, real *, integer *);
extern doublereal slamch_(char *), clanhs_(char *, integer *,
complex *, integer *, real *);
extern /* Subroutine */ int xerbla_(char *, integer *);
logical noinit;
integer ldwork;
logical rightv, fromqr;
real smlnum;
/* -- LAPACK routine (version 3.2) -- */
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/* November 2006 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* CHSEIN uses inverse iteration to find specified right and/or left */
/* eigenvectors of a complex upper Hessenberg matrix H. */
/* The right eigenvector x and the left eigenvector y of the matrix H */
/* corresponding to an eigenvalue w are defined by: */
/* H * x = w * x, y**h * H = w * y**h */
/* where y**h denotes the conjugate transpose of the vector y. */
/* Arguments */
/* ========= */
/* SIDE (input) CHARACTER*1 */
/* = 'R': compute right eigenvectors only; */
/* = 'L': compute left eigenvectors only; */
/* = 'B': compute both right and left eigenvectors. */
/* EIGSRC (input) CHARACTER*1 */
/* Specifies the source of eigenvalues supplied in W: */
/* = 'Q': the eigenvalues were found using CHSEQR; thus, if */
/* H has zero subdiagonal elements, and so is */
/* block-triangular, then the j-th eigenvalue can be */
/* assumed to be an eigenvalue of the block containing */
/* the j-th row/column. This property allows CHSEIN to */
/* perform inverse iteration on just one diagonal block. */
/* = 'N': no assumptions are made on the correspondence */
/* between eigenvalues and diagonal blocks. In this */
/* case, CHSEIN must always perform inverse iteration */
/* using the whole matrix H. */
/* INITV (input) CHARACTER*1 */
/* = 'N': no initial vectors are supplied; */
/* = 'U': user-supplied initial vectors are stored in the arrays */
/* VL and/or VR. */
/* SELECT (input) LOGICAL array, dimension (N) */
/* Specifies the eigenvectors to be computed. To select the */
/* eigenvector corresponding to the eigenvalue W(j), */
/* SELECT(j) must be set to .TRUE.. */
/* N (input) INTEGER */
/* The order of the matrix H. N >= 0. */
/* H (input) COMPLEX array, dimension (LDH,N) */
/* The upper Hessenberg matrix H. */
/* LDH (input) INTEGER */
/* The leading dimension of the array H. LDH >= max(1,N). */
/* W (input/output) COMPLEX array, dimension (N) */
/* On entry, the eigenvalues of H. */
/* On exit, the real parts of W may have been altered since */
/* close eigenvalues are perturbed slightly in searching for */
/* independent eigenvectors. */
/* VL (input/output) COMPLEX array, dimension (LDVL,MM) */
/* On entry, if INITV = 'U' and SIDE = 'L' or 'B', VL must */
/* contain starting vectors for the inverse iteration for the */
/* left eigenvectors; the starting vector for each eigenvector */
/* must be in the same column in which the eigenvector will be */
/* stored. */
/* On exit, if SIDE = 'L' or 'B', the left eigenvectors */
/* specified by SELECT will be stored consecutively in the */
/* columns of VL, in the same order as their eigenvalues. */
/* If SIDE = 'R', VL is not referenced. */
/* LDVL (input) INTEGER */
/* The leading dimension of the array VL. */
/* LDVL >= max(1,N) if SIDE = 'L' or 'B'; LDVL >= 1 otherwise. */
/* VR (input/output) COMPLEX array, dimension (LDVR,MM) */
/* On entry, if INITV = 'U' and SIDE = 'R' or 'B', VR must */
/* contain starting vectors for the inverse iteration for the */
/* right eigenvectors; the starting vector for each eigenvector */
/* must be in the same column in which the eigenvector will be */
/* stored. */
/* On exit, if SIDE = 'R' or 'B', the right eigenvectors */
/* specified by SELECT will be stored consecutively in the */
/* columns of VR, in the same order as their eigenvalues. */
/* If SIDE = 'L', VR is not referenced. */
/* LDVR (input) INTEGER */
/* The leading dimension of the array VR. */
/* LDVR >= max(1,N) if SIDE = 'R' or 'B'; LDVR >= 1 otherwise. */
/* MM (input) INTEGER */
/* The number of columns in the arrays VL and/or VR. MM >= M. */
/* M (output) INTEGER */
/* The number of columns in the arrays VL and/or VR required to */
/* store the eigenvectors (= the number of .TRUE. elements in */
/* SELECT). */
/* WORK (workspace) COMPLEX array, dimension (N*N) */
/* RWORK (workspace) REAL array, dimension (N) */
/* IFAILL (output) INTEGER array, dimension (MM) */
/* If SIDE = 'L' or 'B', IFAILL(i) = j > 0 if the left */
/* eigenvector in the i-th column of VL (corresponding to the */
/* eigenvalue w(j)) failed to converge; IFAILL(i) = 0 if the */
/* eigenvector converged satisfactorily. */
/* If SIDE = 'R', IFAILL is not referenced. */
/* IFAILR (output) INTEGER array, dimension (MM) */
/* If SIDE = 'R' or 'B', IFAILR(i) = j > 0 if the right */
/* eigenvector in the i-th column of VR (corresponding to the */
/* eigenvalue w(j)) failed to converge; IFAILR(i) = 0 if the */
/* eigenvector converged satisfactorily. */
/* If SIDE = 'L', IFAILR is not referenced. */
/* INFO (output) INTEGER */
/* = 0: successful exit */
/* < 0: if INFO = -i, the i-th argument had an illegal value */
/* > 0: if INFO = i, i is the number of eigenvectors which */
/* failed to converge; see IFAILL and IFAILR for further */
/* details. */
/* Further Details */
/* =============== */
/* Each eigenvector is normalized so that the element of largest */
/* magnitude has magnitude 1; here the magnitude of a complex number */
/* (x,y) is taken to be |x|+|y|. */
/* ===================================================================== */
/* .. Parameters .. */
/* .. */
/* .. Local Scalars .. */
/* .. */
/* .. External Functions .. */
/* .. */
/* .. External Subroutines .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* .. Statement Functions .. */
/* .. */
/* .. Statement Function definitions .. */
/* .. */
/* .. Executable Statements .. */
/* Decode and test the input parameters. */
/* Parameter adjustments */
--select;
h_dim1 = *ldh;
h_offset = 1 + h_dim1;
h__ -= h_offset;
--w;
vl_dim1 = *ldvl;
vl_offset = 1 + vl_dim1;
vl -= vl_offset;
vr_dim1 = *ldvr;
vr_offset = 1 + vr_dim1;
vr -= vr_offset;
--work;
--rwork;
--ifaill;
--ifailr;
/* Function Body */
bothv = lsame_(side, "B");
rightv = lsame_(side, "R") || bothv;
leftv = lsame_(side, "L") || bothv;
fromqr = lsame_(eigsrc, "Q");
noinit = lsame_(initv, "N");
/* Set M to the number of columns required to store the selected */
/* eigenvectors. */
*m = 0;
i__1 = *n;
for (k = 1; k <= i__1; ++k) {
if (select[k]) {
++(*m);
}
/* L10: */
}
*info = 0;
if (! rightv && ! leftv) {
*info = -1;
} else if (! fromqr && ! lsame_(eigsrc, "N")) {
*info = -2;
} else if (! noinit && ! lsame_(initv, "U")) {
*info = -3;
} else if (*n < 0) {
*info = -5;
} else if (*ldh < max(1,*n)) {
*info = -7;
} else if (*ldvl < 1 || leftv && *ldvl < *n) {
*info = -10;
} else if (*ldvr < 1 || rightv && *ldvr < *n) {
*info = -12;
} else if (*mm < *m) {
*info = -13;
}
if (*info != 0) {
i__1 = -(*info);
xerbla_("CHSEIN", &i__1);
return 0;
}
/* Quick return if possible. */
if (*n == 0) {
return 0;
}
/* Set machine-dependent constants. */
unfl = slamch_("Safe minimum");
ulp = slamch_("Precision");
smlnum = unfl * (*n / ulp);
ldwork = *n;
kl = 1;
kln = 0;
if (fromqr) {
kr = 0;
} else {
kr = *n;
}
ks = 1;
i__1 = *n;
for (k = 1; k <= i__1; ++k) {
if (select[k]) {
/* Compute eigenvector(s) corresponding to W(K). */
if (fromqr) {
/* If affiliation of eigenvalues is known, check whether */
/* the matrix splits. */
/* Determine KL and KR such that 1 <= KL <= K <= KR <= N */
/* and H(KL,KL-1) and H(KR+1,KR) are zero (or KL = 1 or */
/* KR = N). */
/* Then inverse iteration can be performed with the */
/* submatrix H(KL:N,KL:N) for a left eigenvector, and with */
/* the submatrix H(1:KR,1:KR) for a right eigenvector. */
i__2 = kl + 1;
for (i__ = k; i__ >= i__2; --i__) {
i__3 = i__ + (i__ - 1) * h_dim1;
if (h__[i__3].r == 0.f && h__[i__3].i == 0.f) {
goto L30;
}
/* L20: */
}
L30:
kl = i__;
if (k > kr) {
i__2 = *n - 1;
for (i__ = k; i__ <= i__2; ++i__) {
i__3 = i__ + 1 + i__ * h_dim1;
if (h__[i__3].r == 0.f && h__[i__3].i == 0.f) {
goto L50;
}
/* L40: */
}
L50:
kr = i__;
}
}
if (kl != kln) {
kln = kl;
/* Compute infinity-norm of submatrix H(KL:KR,KL:KR) if it */
/* has not ben computed before. */
i__2 = kr - kl + 1;
hnorm = clanhs_("I", &i__2, &h__[kl + kl * h_dim1], ldh, &
rwork[1]);
if (hnorm > 0.f) {
eps3 = hnorm * ulp;
} else {
eps3 = smlnum;
}
}
/* Perturb eigenvalue if it is close to any previous */
/* selected eigenvalues affiliated to the submatrix */
/* H(KL:KR,KL:KR). Close roots are modified by EPS3. */
i__2 = k;
wk.r = w[i__2].r, wk.i = w[i__2].i;
L60:
i__2 = kl;
for (i__ = k - 1; i__ >= i__2; --i__) {
i__3 = i__;
q__2.r = w[i__3].r - wk.r, q__2.i = w[i__3].i - wk.i;
q__1.r = q__2.r, q__1.i = q__2.i;
if (select[i__] && (r__1 = q__1.r, dabs(r__1)) + (r__2 =
r_imag(&q__1), dabs(r__2)) < eps3) {
q__1.r = wk.r + eps3, q__1.i = wk.i;
wk.r = q__1.r, wk.i = q__1.i;
goto L60;
}
/* L70: */
}
i__2 = k;
w[i__2].r = wk.r, w[i__2].i = wk.i;
if (leftv) {
/* Compute left eigenvector. */
i__2 = *n - kl + 1;
claein_(&c_false, &noinit, &i__2, &h__[kl + kl * h_dim1], ldh,
&wk, &vl[kl + ks * vl_dim1], &work[1], &ldwork, &
rwork[1], &eps3, &smlnum, &iinfo);
if (iinfo > 0) {
++(*info);
ifaill[ks] = k;
} else {
ifaill[ks] = 0;
}
i__2 = kl - 1;
for (i__ = 1; i__ <= i__2; ++i__) {
i__3 = i__ + ks * vl_dim1;
vl[i__3].r = 0.f, vl[i__3].i = 0.f;
/* L80: */
}
}
if (rightv) {
/* Compute right eigenvector. */
claein_(&c_true, &noinit, &kr, &h__[h_offset], ldh, &wk, &vr[
ks * vr_dim1 + 1], &work[1], &ldwork, &rwork[1], &
eps3, &smlnum, &iinfo);
if (iinfo > 0) {
++(*info);
ifailr[ks] = k;
} else {
ifailr[ks] = 0;
}
i__2 = *n;
for (i__ = kr + 1; i__ <= i__2; ++i__) {
i__3 = i__ + ks * vr_dim1;
vr[i__3].r = 0.f, vr[i__3].i = 0.f;
/* L90: */
}
}
++ks;
}
/* L100: */
}
return 0;
/* End of CHSEIN */
} /* chsein_ */
|
