/* zlaqr4.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 integer c__13 = 13;
static integer c__15 = 15;
static integer c_n1 = -1;
static integer c__12 = 12;
static integer c__14 = 14;
static integer c__16 = 16;
static logical c_false = FALSE_;
static integer c__1 = 1;
static integer c__3 = 3;
/* Subroutine */ int zlaqr4_(logical *wantt, logical *wantz, integer *n,
integer *ilo, integer *ihi, doublecomplex *h__, integer *ldh,
doublecomplex *w, integer *iloz, integer *ihiz, doublecomplex *z__,
integer *ldz, doublecomplex *work, integer *lwork, integer *info)
{
/* System generated locals */
integer h_dim1, h_offset, z_dim1, z_offset, i__1, i__2, i__3, i__4, i__5;
doublereal d__1, d__2, d__3, d__4, d__5, d__6, d__7, d__8;
doublecomplex z__1, z__2, z__3, z__4, z__5;
/* Builtin functions */
double d_imag(doublecomplex *);
void z_sqrt(doublecomplex *, doublecomplex *);
/* Local variables */
integer i__, k;
doublereal s;
doublecomplex aa, bb, cc, dd;
integer ld, nh, it, ks, kt, ku, kv, ls, ns, nw;
doublecomplex tr2, det;
integer inf, kdu, nho, nve, kwh, nsr, nwr, kwv, ndec, ndfl, kbot, nmin;
doublecomplex swap;
integer ktop;
doublecomplex zdum[1] /* was [1][1] */;
integer kacc22, itmax, nsmax, nwmax, kwtop;
extern /* Subroutine */ int zlaqr2_(logical *, logical *, integer *,
integer *, integer *, integer *, doublecomplex *, integer *,
integer *, integer *, doublecomplex *, integer *, integer *,
integer *, doublecomplex *, doublecomplex *, integer *, integer *,
doublecomplex *, integer *, integer *, doublecomplex *, integer *
, doublecomplex *, integer *), zlaqr5_(logical *, logical *,
integer *, integer *, integer *, integer *, integer *,
doublecomplex *, doublecomplex *, integer *, integer *, integer *,
doublecomplex *, integer *, doublecomplex *, integer *,
doublecomplex *, integer *, integer *, doublecomplex *, integer *,
integer *, doublecomplex *, integer *);
integer nibble;
extern integer ilaenv_(integer *, char *, char *, integer *, integer *,
integer *, integer *);
char jbcmpz[1];
doublecomplex rtdisc;
integer nwupbd;
logical sorted;
extern /* Subroutine */ int zlahqr_(logical *, logical *, integer *,
integer *, integer *, doublecomplex *, integer *, doublecomplex *,
integer *, integer *, doublecomplex *, integer *, integer *),
zlacpy_(char *, integer *, integer *, doublecomplex *, integer *,
doublecomplex *, integer *);
integer lwkopt;
/* -- LAPACK auxiliary routine (version 3.2) -- */
/* Univ. of Tennessee, Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd.. */
/* November 2006 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* This subroutine implements one level of recursion for ZLAQR0. */
/* It is a complete implementation of the small bulge multi-shift */
/* QR algorithm. It may be called by ZLAQR0 and, for large enough */
/* deflation window size, it may be called by ZLAQR3. This */
/* subroutine is identical to ZLAQR0 except that it calls ZLAQR2 */
/* instead of ZLAQR3. */
/* Purpose */
/* ======= */
/* ZLAQR4 computes the eigenvalues of a Hessenberg matrix H */
/* and, optionally, the matrices T and Z from the Schur decomposition */
/* H = Z T Z**H, where T is an upper triangular matrix (the */
/* Schur form), and Z is the unitary matrix of Schur vectors. */
/* Optionally Z may be postmultiplied into an input unitary */
/* matrix Q so that this routine can give the Schur factorization */
/* of a matrix A which has been reduced to the Hessenberg form H */
/* by the unitary matrix Q: A = Q*H*Q**H = (QZ)*H*(QZ)**H. */
/* Arguments */
/* ========= */
/* WANTT (input) LOGICAL */
/* = .TRUE. : the full Schur form T is required; */
/* = .FALSE.: only eigenvalues are required. */
/* WANTZ (input) LOGICAL */
/* = .TRUE. : the matrix of Schur vectors Z is required; */
/* = .FALSE.: Schur vectors are not required. */
/* N (input) INTEGER */
/* The order of the matrix H. N .GE. 0. */
/* ILO (input) INTEGER */
/* IHI (input) INTEGER */
/* It is assumed that H is already upper triangular in rows */
/* and columns 1:ILO-1 and IHI+1:N and, if ILO.GT.1, */
/* H(ILO,ILO-1) is zero. ILO and IHI are normally set by a */
/* previous call to ZGEBAL, and then passed to ZGEHRD when the */
/* matrix output by ZGEBAL is reduced to Hessenberg form. */
/* Otherwise, ILO and IHI should be set to 1 and N, */
/* respectively. If N.GT.0, then 1.LE.ILO.LE.IHI.LE.N. */
/* If N = 0, then ILO = 1 and IHI = 0. */
/* H (input/output) COMPLEX*16 array, dimension (LDH,N) */
/* On entry, the upper Hessenberg matrix H. */
/* On exit, if INFO = 0 and WANTT is .TRUE., then H */
/* contains the upper triangular matrix T from the Schur */
/* decomposition (the Schur form). If INFO = 0 and WANT is */
/* .FALSE., then the contents of H are unspecified on exit. */
/* (The output value of H when INFO.GT.0 is given under the */
/* description of INFO below.) */
/* This subroutine may explicitly set H(i,j) = 0 for i.GT.j and */
/* j = 1, 2, ... ILO-1 or j = IHI+1, IHI+2, ... N. */
/* LDH (input) INTEGER */
/* The leading dimension of the array H. LDH .GE. max(1,N). */
/* W (output) COMPLEX*16 array, dimension (N) */
/* The computed eigenvalues of H(ILO:IHI,ILO:IHI) are stored */
/* in W(ILO:IHI). If WANTT is .TRUE., then the eigenvalues are */
/* stored in the same order as on the diagonal of the Schur */
/* form returned in H, with W(i) = H(i,i). */
/* Z (input/output) COMPLEX*16 array, dimension (LDZ,IHI) */
/* If WANTZ is .FALSE., then Z is not referenced. */
/* If WANTZ is .TRUE., then Z(ILO:IHI,ILOZ:IHIZ) is */
/* replaced by Z(ILO:IHI,ILOZ:IHIZ)*U where U is the */
/* orthogonal Schur factor of H(ILO:IHI,ILO:IHI). */
/* (The output value of Z when INFO.GT.0 is given under */
/* the description of INFO below.) */
/* LDZ (input) INTEGER */
/* The leading dimension of the array Z. if WANTZ is .TRUE. */
/* then LDZ.GE.MAX(1,IHIZ). Otherwize, LDZ.GE.1. */
/* WORK (workspace/output) COMPLEX*16 array, dimension LWORK */
/* On exit, if LWORK = -1, WORK(1) returns an estimate of */
/* the optimal value for LWORK. */
/* LWORK (input) INTEGER */
/* The dimension of the array WORK. LWORK .GE. max(1,N) */
/* is sufficient, but LWORK typically as large as 6*N may */
/* be required for optimal performance. A workspace query */
/* to determine the optimal workspace size is recommended. */
/* If LWORK = -1, then ZLAQR4 does a workspace query. */
/* In this case, ZLAQR4 checks the input parameters and */
/* estimates the optimal workspace size for the given */
/* values of N, ILO and IHI. The estimate is returned */
/* in WORK(1). No error message related to LWORK is */
/* issued by XERBLA. Neither H nor Z are accessed. */
/* INFO (output) INTEGER */
/* = 0: successful exit */
/* .GT. 0: if INFO = i, ZLAQR4 failed to compute all of */
/* the eigenvalues. Elements 1:ilo-1 and i+1:n of WR */
/* and WI contain those eigenvalues which have been */
/* successfully computed. (Failures are rare.) */
/* If INFO .GT. 0 and WANT is .FALSE., then on exit, */
/* the remaining unconverged eigenvalues are the eigen- */
/* values of the upper Hessenberg matrix rows and */
/* columns ILO through INFO of the final, output */
/* value of H. */
/* If INFO .GT. 0 and WANTT is .TRUE., then on exit */
/* (*) (initial value of H)*U = U*(final value of H) */
/* where U is a unitary matrix. The final */
/* value of H is upper Hessenberg and triangular in */
/* rows and columns INFO+1 through IHI. */
/* If INFO .GT. 0 and WANTZ is .TRUE., then on exit */
/* (final value of Z(ILO:IHI,ILOZ:IHIZ) */
/* = (initial value of Z(ILO:IHI,ILOZ:IHIZ)*U */
/* where U is the unitary matrix in (*) (regard- */
/* less of the value of WANTT.) */
/* If INFO .GT. 0 and WANTZ is .FALSE., then Z is not */
/* accessed. */
/* ================================================================ */
/* Based on contributions by */
/* Karen Braman and Ralph Byers, Department of Mathematics, */
/* University of Kansas, USA */
/* ================================================================ */
/* References: */
/* K. Braman, R. Byers and R. Mathias, The Multi-Shift QR */
/* Algorithm Part I: Maintaining Well Focused Shifts, and Level 3 */
/* Performance, SIAM Journal of Matrix Analysis, volume 23, pages */
/* 929--947, 2002. */
/* K. Braman, R. Byers and R. Mathias, The Multi-Shift QR */
/* Algorithm Part II: Aggressive Early Deflation, SIAM Journal */
/* of Matrix Analysis, volume 23, pages 948--973, 2002. */
/* ================================================================ */
/* .. Parameters .. */
/* ==== Matrices of order NTINY or smaller must be processed by */
/* . ZLAHQR because of insufficient subdiagonal scratch space. */
/* . (This is a hard limit.) ==== */
/* ==== Exceptional deflation windows: try to cure rare */
/* . slow convergence by varying the size of the */
/* . deflation window after KEXNW iterations. ==== */
/* ==== Exceptional shifts: try to cure rare slow convergence */
/* . with ad-hoc exceptional shifts every KEXSH iterations. */
/* . ==== */
/* ==== The constant WILK1 is used to form the exceptional */
/* . shifts. ==== */
/* .. */
/* .. Local Scalars .. */
/* .. */
/* .. External Functions .. */
/* .. */
/* .. Local Arrays .. */
/* .. */
/* .. External Subroutines .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* .. Statement Functions .. */
/* .. */
/* .. Statement Function definitions .. */
/* .. */
/* .. Executable Statements .. */
/* Parameter adjustments */
h_dim1 = *ldh;
h_offset = 1 + h_dim1;
h__ -= h_offset;
--w;
z_dim1 = *ldz;
z_offset = 1 + z_dim1;
z__ -= z_offset;
--work;
/* Function Body */
*info = 0;
/* ==== Quick return for N = 0: nothing to do. ==== */
if (*n == 0) {
work[1].r = 1., work[1].i = 0.;
return 0;
}
if (*n <= 11) {
/* ==== Tiny matrices must use ZLAHQR. ==== */
lwkopt = 1;
if (*lwork != -1) {
zlahqr_(wantt, wantz, n, ilo, ihi, &h__[h_offset], ldh, &w[1],
iloz, ihiz, &z__[z_offset], ldz, info);
}
} else {
/* ==== Use small bulge multi-shift QR with aggressive early */
/* . deflation on larger-than-tiny matrices. ==== */
/* ==== Hope for the best. ==== */
*info = 0;
/* ==== Set up job flags for ILAENV. ==== */
if (*wantt) {
*(unsigned char *)jbcmpz = 'S';
} else {
*(unsigned char *)jbcmpz = 'E';
}
if (*wantz) {
*(unsigned char *)&jbcmpz[1] = 'V';
} else {
*(unsigned char *)&jbcmpz[1] = 'N';
}
/* ==== NWR = recommended deflation window size. At this */
/* . point, N .GT. NTINY = 11, so there is enough */
/* . subdiagonal workspace for NWR.GE.2 as required. */
/* . (In fact, there is enough subdiagonal space for */
/* . NWR.GE.3.) ==== */
nwr = ilaenv_(&c__13, "ZLAQR4", jbcmpz, n, ilo, ihi, lwork);
nwr = max(2,nwr);
/* Computing MIN */
i__1 = *ihi - *ilo + 1, i__2 = (*n - 1) / 3, i__1 = min(i__1,i__2);
nwr = min(i__1,nwr);
/* ==== NSR = recommended number of simultaneous shifts. */
/* . At this point N .GT. NTINY = 11, so there is at */
/* . enough subdiagonal workspace for NSR to be even */
/* . and greater than or equal to two as required. ==== */
nsr = ilaenv_(&c__15, "ZLAQR4", jbcmpz, n, ilo, ihi, lwork);
/* Computing MIN */
i__1 = nsr, i__2 = (*n + 6) / 9, i__1 = min(i__1,i__2), i__2 = *ihi -
*ilo;
nsr = min(i__1,i__2);
/* Computing MAX */
i__1 = 2, i__2 = nsr - nsr % 2;
nsr = max(i__1,i__2);
/* ==== Estimate optimal workspace ==== */
/* ==== Workspace query call to ZLAQR2 ==== */
i__1 = nwr + 1;
zlaqr2_(wantt, wantz, n, ilo, ihi, &i__1, &h__[h_offset], ldh, iloz,
ihiz, &z__[z_offset], ldz, &ls, &ld, &w[1], &h__[h_offset],
ldh, n, &h__[h_offset], ldh, n, &h__[h_offset], ldh, &work[1],
&c_n1);
/* ==== Optimal workspace = MAX(ZLAQR5, ZLAQR2) ==== */
/* Computing MAX */
i__1 = nsr * 3 / 2, i__2 = (integer) work[1].r;
lwkopt = max(i__1,i__2);
/* ==== Quick return in case of workspace query. ==== */
if (*lwork == -1) {
d__1 = (doublereal) lwkopt;
z__1.r = d__1, z__1.i = 0.;
work[1].r = z__1.r, work[1].i = z__1.i;
return 0;
}
/* ==== ZLAHQR/ZLAQR0 crossover point ==== */
nmin = ilaenv_(&c__12, "ZLAQR4", jbcmpz, n, ilo, ihi, lwork);
nmin = max(11,nmin);
/* ==== Nibble crossover point ==== */
nibble = ilaenv_(&c__14, "ZLAQR4", jbcmpz, n, ilo, ihi, lwork);
nibble = max(0,nibble);
/* ==== Accumulate reflections during ttswp? Use block */
/* . 2-by-2 structure during matrix-matrix multiply? ==== */
kacc22 = ilaenv_(&c__16, "ZLAQR4", jbcmpz, n, ilo, ihi, lwork);
kacc22 = max(0,kacc22);
kacc22 = min(2,kacc22);
/* ==== NWMAX = the largest possible deflation window for */
/* . which there is sufficient workspace. ==== */
/* Computing MIN */
i__1 = (*n - 1) / 3, i__2 = *lwork / 2;
nwmax = min(i__1,i__2);
nw = nwmax;
/* ==== NSMAX = the Largest number of simultaneous shifts */
/* . for which there is sufficient workspace. ==== */
/* Computing MIN */
i__1 = (*n + 6) / 9, i__2 = (*lwork << 1) / 3;
nsmax = min(i__1,i__2);
nsmax -= nsmax % 2;
/* ==== NDFL: an iteration count restarted at deflation. ==== */
ndfl = 1;
/* ==== ITMAX = iteration limit ==== */
/* Computing MAX */
i__1 = 10, i__2 = *ihi - *ilo + 1;
itmax = max(i__1,i__2) * 30;
/* ==== Last row and column in the active block ==== */
kbot = *ihi;
/* ==== Main Loop ==== */
i__1 = itmax;
for (it = 1; it <= i__1; ++it) {
/* ==== Done when KBOT falls below ILO ==== */
if (kbot < *ilo) {
goto L80;
}
/* ==== Locate active block ==== */
i__2 = *ilo + 1;
for (k = kbot; k >= i__2; --k) {
i__3 = k + (k - 1) * h_dim1;
if (h__[i__3].r == 0. && h__[i__3].i == 0.) {
goto L20;
}
/* L10: */
}
k = *ilo;
L20:
ktop = k;
/* ==== Select deflation window size: */
/* . Typical Case: */
/* . If possible and advisable, nibble the entire */
/* . active block. If not, use size MIN(NWR,NWMAX) */
/* . or MIN(NWR+1,NWMAX) depending upon which has */
/* . the smaller corresponding subdiagonal entry */
/* . (a heuristic). */
/* . */
/* . Exceptional Case: */
/* . If there have been no deflations in KEXNW or */
/* . more iterations, then vary the deflation window */
/* . size. At first, because, larger windows are, */
/* . in general, more powerful than smaller ones, */
/* . rapidly increase the window to the maximum possible. */
/* . Then, gradually reduce the window size. ==== */
nh = kbot - ktop + 1;
nwupbd = min(nh,nwmax);
if (ndfl < 5) {
nw = min(nwupbd,nwr);
} else {
/* Computing MIN */
i__2 = nwupbd, i__3 = nw << 1;
nw = min(i__2,i__3);
}
if (nw < nwmax) {
if (nw >= nh - 1) {
nw = nh;
} else {
kwtop = kbot - nw + 1;
i__2 = kwtop + (kwtop - 1) * h_dim1;
i__3 = kwtop - 1 + (kwtop - 2) * h_dim1;
if ((d__1 = h__[i__2].r, abs(d__1)) + (d__2 = d_imag(&h__[
kwtop + (kwtop - 1) * h_dim1]), abs(d__2)) > (
d__3 = h__[i__3].r, abs(d__3)) + (d__4 = d_imag(&
h__[kwtop - 1 + (kwtop - 2) * h_dim1]), abs(d__4))
) {
++nw;
}
}
}
if (ndfl < 5) {
ndec = -1;
} else if (ndec >= 0 || nw >= nwupbd) {
++ndec;
if (nw - ndec < 2) {
ndec = 0;
}
nw -= ndec;
}
/* ==== Aggressive early deflation: */
/* . split workspace under the subdiagonal into */
/* . - an nw-by-nw work array V in the lower */
/* . left-hand-corner, */
/* . - an NW-by-at-least-NW-but-more-is-better */
/* . (NW-by-NHO) horizontal work array along */
/* . the bottom edge, */
/* . - an at-least-NW-but-more-is-better (NHV-by-NW) */
/* . vertical work array along the left-hand-edge. */
/* . ==== */
kv = *n - nw + 1;
kt = nw + 1;
nho = *n - nw - 1 - kt + 1;
kwv = nw + 2;
nve = *n - nw - kwv + 1;
/* ==== Aggressive early deflation ==== */
zlaqr2_(wantt, wantz, n, &ktop, &kbot, &nw, &h__[h_offset], ldh,
iloz, ihiz, &z__[z_offset], ldz, &ls, &ld, &w[1], &h__[kv
+ h_dim1], ldh, &nho, &h__[kv + kt * h_dim1], ldh, &nve, &
h__[kwv + h_dim1], ldh, &work[1], lwork);
/* ==== Adjust KBOT accounting for new deflations. ==== */
kbot -= ld;
/* ==== KS points to the shifts. ==== */
ks = kbot - ls + 1;
/* ==== Skip an expensive QR sweep if there is a (partly */
/* . heuristic) reason to expect that many eigenvalues */
/* . will deflate without it. Here, the QR sweep is */
/* . skipped if many eigenvalues have just been deflated */
/* . or if the remaining active block is small. */
if (ld == 0 || ld * 100 <= nw * nibble && kbot - ktop + 1 > min(
nmin,nwmax)) {
/* ==== NS = nominal number of simultaneous shifts. */
/* . This may be lowered (slightly) if ZLAQR2 */
/* . did not provide that many shifts. ==== */
/* Computing MIN */
/* Computing MAX */
i__4 = 2, i__5 = kbot - ktop;
i__2 = min(nsmax,nsr), i__3 = max(i__4,i__5);
ns = min(i__2,i__3);
ns -= ns % 2;
/* ==== If there have been no deflations */
/* . in a multiple of KEXSH iterations, */
/* . then try exceptional shifts. */
/* . Otherwise use shifts provided by */
/* . ZLAQR2 above or from the eigenvalues */
/* . of a trailing principal submatrix. ==== */
if (ndfl % 6 == 0) {
ks = kbot - ns + 1;
i__2 = ks + 1;
for (i__ = kbot; i__ >= i__2; i__ += -2) {
i__3 = i__;
i__4 = i__ + i__ * h_dim1;
i__5 = i__ + (i__ - 1) * h_dim1;
d__3 = ((d__1 = h__[i__5].r, abs(d__1)) + (d__2 =
d_imag(&h__[i__ + (i__ - 1) * h_dim1]), abs(
d__2))) * .75;
z__1.r = h__[i__4].r + d__3, z__1.i = h__[i__4].i;
w[i__3].r = z__1.r, w[i__3].i = z__1.i;
i__3 = i__ - 1;
i__4 = i__;
w[i__3].r = w[i__4].r, w[i__3].i = w[i__4].i;
/* L30: */
}
} else {
/* ==== Got NS/2 or fewer shifts? Use ZLAHQR */
/* . on a trailing principal submatrix to */
/* . get more. (Since NS.LE.NSMAX.LE.(N+6)/9, */
/* . there is enough space below the subdiagonal */
/* . to fit an NS-by-NS scratch array.) ==== */
if (kbot - ks + 1 <= ns / 2) {
ks = kbot - ns + 1;
kt = *n - ns + 1;
zlacpy_("A", &ns, &ns, &h__[ks + ks * h_dim1], ldh, &
h__[kt + h_dim1], ldh);
zlahqr_(&c_false, &c_false, &ns, &c__1, &ns, &h__[kt
+ h_dim1], ldh, &w[ks], &c__1, &c__1, zdum, &
c__1, &inf);
ks += inf;
/* ==== In case of a rare QR failure use */
/* . eigenvalues of the trailing 2-by-2 */
/* . principal submatrix. Scale to avoid */
/* . overflows, underflows and subnormals. */
/* . (The scale factor S can not be zero, */
/* . because H(KBOT,KBOT-1) is nonzero.) ==== */
if (ks >= kbot) {
i__2 = kbot - 1 + (kbot - 1) * h_dim1;
i__3 = kbot + (kbot - 1) * h_dim1;
i__4 = kbot - 1 + kbot * h_dim1;
i__5 = kbot + kbot * h_dim1;
s = (d__1 = h__[i__2].r, abs(d__1)) + (d__2 =
d_imag(&h__[kbot - 1 + (kbot - 1) *
h_dim1]), abs(d__2)) + ((d__3 = h__[i__3]
.r, abs(d__3)) + (d__4 = d_imag(&h__[kbot
+ (kbot - 1) * h_dim1]), abs(d__4))) + ((
d__5 = h__[i__4].r, abs(d__5)) + (d__6 =
d_imag(&h__[kbot - 1 + kbot * h_dim1]),
abs(d__6))) + ((d__7 = h__[i__5].r, abs(
d__7)) + (d__8 = d_imag(&h__[kbot + kbot *
h_dim1]), abs(d__8)));
i__2 = kbot - 1 + (kbot - 1) * h_dim1;
z__1.r = h__[i__2].r / s, z__1.i = h__[i__2].i /
s;
aa.r = z__1.r, aa.i = z__1.i;
i__2 = kbot + (kbot - 1) * h_dim1;
z__1.r = h__[i__2].r / s, z__1.i = h__[i__2].i /
s;
cc.r = z__1.r, cc.i = z__1.i;
i__2 = kbot - 1 + kbot * h_dim1;
z__1.r = h__[i__2].r / s, z__1.i = h__[i__2].i /
s;
bb.r = z__1.r, bb.i = z__1.i;
i__2 = kbot + kbot * h_dim1;
z__1.r = h__[i__2].r / s, z__1.i = h__[i__2].i /
s;
dd.r = z__1.r, dd.i = z__1.i;
z__2.r = aa.r + dd.r, z__2.i = aa.i + dd.i;
z__1.r = z__2.r / 2., z__1.i = z__2.i / 2.;
tr2.r = z__1.r, tr2.i = z__1.i;
z__3.r = aa.r - tr2.r, z__3.i = aa.i - tr2.i;
z__4.r = dd.r - tr2.r, z__4.i = dd.i - tr2.i;
z__2.r = z__3.r * z__4.r - z__3.i * z__4.i,
z__2.i = z__3.r * z__4.i + z__3.i *
z__4.r;
z__5.r = bb.r * cc.r - bb.i * cc.i, z__5.i = bb.r
* cc.i + bb.i * cc.r;
z__1.r = z__2.r - z__5.r, z__1.i = z__2.i -
z__5.i;
det.r = z__1.r, det.i = z__1.i;
z__2.r = -det.r, z__2.i = -det.i;
z_sqrt(&z__1, &z__2);
rtdisc.r = z__1.r, rtdisc.i = z__1.i;
i__2 = kbot - 1;
z__2.r = tr2.r + rtdisc.r, z__2.i = tr2.i +
rtdisc.i;
z__1.r = s * z__2.r, z__1.i = s * z__2.i;
w[i__2].r = z__1.r, w[i__2].i = z__1.i;
i__2 = kbot;
z__2.r = tr2.r - rtdisc.r, z__2.i = tr2.i -
rtdisc.i;
z__1.r = s * z__2.r, z__1.i = s * z__2.i;
w[i__2].r = z__1.r, w[i__2].i = z__1.i;
ks = kbot - 1;
}
}
if (kbot - ks + 1 > ns) {
/* ==== Sort the shifts (Helps a little) ==== */
sorted = FALSE_;
i__2 = ks + 1;
for (k = kbot; k >= i__2; --k) {
if (sorted) {
goto L60;
}
sorted = TRUE_;
i__3 = k - 1;
for (i__ = ks; i__ <= i__3; ++i__) {
i__4 = i__;
i__5 = i__ + 1;
if ((d__1 = w[i__4].r, abs(d__1)) + (d__2 =
d_imag(&w[i__]), abs(d__2)) < (d__3 =
w[i__5].r, abs(d__3)) + (d__4 =
d_imag(&w[i__ + 1]), abs(d__4))) {
sorted = FALSE_;
i__4 = i__;
swap.r = w[i__4].r, swap.i = w[i__4].i;
i__4 = i__;
i__5 = i__ + 1;
w[i__4].r = w[i__5].r, w[i__4].i = w[i__5]
.i;
i__4 = i__ + 1;
w[i__4].r = swap.r, w[i__4].i = swap.i;
}
/* L40: */
}
/* L50: */
}
L60:
;
}
}
/* ==== If there are only two shifts, then use */
/* . only one. ==== */
if (kbot - ks + 1 == 2) {
i__2 = kbot;
i__3 = kbot + kbot * h_dim1;
z__2.r = w[i__2].r - h__[i__3].r, z__2.i = w[i__2].i -
h__[i__3].i;
z__1.r = z__2.r, z__1.i = z__2.i;
i__4 = kbot - 1;
i__5 = kbot + kbot * h_dim1;
z__4.r = w[i__4].r - h__[i__5].r, z__4.i = w[i__4].i -
h__[i__5].i;
z__3.r = z__4.r, z__3.i = z__4.i;
if ((d__1 = z__1.r, abs(d__1)) + (d__2 = d_imag(&z__1),
abs(d__2)) < (d__3 = z__3.r, abs(d__3)) + (d__4 =
d_imag(&z__3), abs(d__4))) {
i__2 = kbot - 1;
i__3 = kbot;
w[i__2].r = w[i__3].r, w[i__2].i = w[i__3].i;
} else {
i__2 = kbot;
i__3 = kbot - 1;
w[i__2].r = w[i__3].r, w[i__2].i = w[i__3].i;
}
}
/* ==== Use up to NS of the the smallest magnatiude */
/* . shifts. If there aren't NS shifts available, */
/* . then use them all, possibly dropping one to */
/* . make the number of shifts even. ==== */
/* Computing MIN */
i__2 = ns, i__3 = kbot - ks + 1;
ns = min(i__2,i__3);
ns -= ns % 2;
ks = kbot - ns + 1;
/* ==== Small-bulge multi-shift QR sweep: */
/* . split workspace under the subdiagonal into */
/* . - a KDU-by-KDU work array U in the lower */
/* . left-hand-corner, */
/* . - a KDU-by-at-least-KDU-but-more-is-better */
/* . (KDU-by-NHo) horizontal work array WH along */
/* . the bottom edge, */
/* . - and an at-least-KDU-but-more-is-better-by-KDU */
/* . (NVE-by-KDU) vertical work WV arrow along */
/* . the left-hand-edge. ==== */
kdu = ns * 3 - 3;
ku = *n - kdu + 1;
kwh = kdu + 1;
nho = *n - kdu - 3 - (kdu + 1) + 1;
kwv = kdu + 4;
nve = *n - kdu - kwv + 1;
/* ==== Small-bulge multi-shift QR sweep ==== */
zlaqr5_(wantt, wantz, &kacc22, n, &ktop, &kbot, &ns, &w[ks], &
h__[h_offset], ldh, iloz, ihiz, &z__[z_offset], ldz, &
work[1], &c__3, &h__[ku + h_dim1], ldh, &nve, &h__[
kwv + h_dim1], ldh, &nho, &h__[ku + kwh * h_dim1],
ldh);
}
/* ==== Note progress (or the lack of it). ==== */
if (ld > 0) {
ndfl = 1;
} else {
++ndfl;
}
/* ==== End of main loop ==== */
/* L70: */
}
/* ==== Iteration limit exceeded. Set INFO to show where */
/* . the problem occurred and exit. ==== */
*info = kbot;
L80:
;
}
/* ==== Return the optimal value of LWORK. ==== */
d__1 = (doublereal) lwkopt;
z__1.r = d__1, z__1.i = 0.;
work[1].r = z__1.r, work[1].i = z__1.i;
/* ==== End of ZLAQR4 ==== */
return 0;
} /* zlaqr4_ */
