OpenBLAS/lapack-netlib/SRC/slarrb.c

941 lines
26 KiB
C

#include <math.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <complex.h>
#ifdef complex
#undef complex
#endif
#ifdef I
#undef I
#endif
#if defined(_WIN64)
typedef long long BLASLONG;
typedef unsigned long long BLASULONG;
#else
typedef long BLASLONG;
typedef unsigned long BLASULONG;
#endif
#ifdef LAPACK_ILP64
typedef BLASLONG blasint;
#if defined(_WIN64)
#define blasabs(x) llabs(x)
#else
#define blasabs(x) labs(x)
#endif
#else
typedef int blasint;
#define blasabs(x) abs(x)
#endif
typedef blasint integer;
typedef unsigned int uinteger;
typedef char *address;
typedef short int shortint;
typedef float real;
typedef double doublereal;
typedef struct { real r, i; } complex;
typedef struct { doublereal r, i; } doublecomplex;
#ifdef _MSC_VER
static inline _Fcomplex Cf(complex *z) {_Fcomplex zz={z->r , z->i}; return zz;}
static inline _Dcomplex Cd(doublecomplex *z) {_Dcomplex zz={z->r , z->i};return zz;}
static inline _Fcomplex * _pCf(complex *z) {return (_Fcomplex*)z;}
static inline _Dcomplex * _pCd(doublecomplex *z) {return (_Dcomplex*)z;}
#else
static inline _Complex float Cf(complex *z) {return z->r + z->i*_Complex_I;}
static inline _Complex double Cd(doublecomplex *z) {return z->r + z->i*_Complex_I;}
static inline _Complex float * _pCf(complex *z) {return (_Complex float*)z;}
static inline _Complex double * _pCd(doublecomplex *z) {return (_Complex double*)z;}
#endif
#define pCf(z) (*_pCf(z))
#define pCd(z) (*_pCd(z))
typedef blasint logical;
typedef char logical1;
typedef char integer1;
#define TRUE_ (1)
#define FALSE_ (0)
/* Extern is for use with -E */
#ifndef Extern
#define Extern extern
#endif
/* I/O stuff */
typedef int flag;
typedef int ftnlen;
typedef int ftnint;
/*external read, write*/
typedef struct
{ flag cierr;
ftnint ciunit;
flag ciend;
char *cifmt;
ftnint cirec;
} cilist;
/*internal read, write*/
typedef struct
{ flag icierr;
char *iciunit;
flag iciend;
char *icifmt;
ftnint icirlen;
ftnint icirnum;
} icilist;
/*open*/
typedef struct
{ flag oerr;
ftnint ounit;
char *ofnm;
ftnlen ofnmlen;
char *osta;
char *oacc;
char *ofm;
ftnint orl;
char *oblnk;
} olist;
/*close*/
typedef struct
{ flag cerr;
ftnint cunit;
char *csta;
} cllist;
/*rewind, backspace, endfile*/
typedef struct
{ flag aerr;
ftnint aunit;
} alist;
/* inquire */
typedef struct
{ flag inerr;
ftnint inunit;
char *infile;
ftnlen infilen;
ftnint *inex; /*parameters in standard's order*/
ftnint *inopen;
ftnint *innum;
ftnint *innamed;
char *inname;
ftnlen innamlen;
char *inacc;
ftnlen inacclen;
char *inseq;
ftnlen inseqlen;
char *indir;
ftnlen indirlen;
char *infmt;
ftnlen infmtlen;
char *inform;
ftnint informlen;
char *inunf;
ftnlen inunflen;
ftnint *inrecl;
ftnint *innrec;
char *inblank;
ftnlen inblanklen;
} inlist;
#define VOID void
union Multitype { /* for multiple entry points */
integer1 g;
shortint h;
integer i;
/* longint j; */
real r;
doublereal d;
complex c;
doublecomplex z;
};
typedef union Multitype Multitype;
struct Vardesc { /* for Namelist */
char *name;
char *addr;
ftnlen *dims;
int type;
};
typedef struct Vardesc Vardesc;
struct Namelist {
char *name;
Vardesc **vars;
int nvars;
};
typedef struct Namelist Namelist;
#define abs(x) ((x) >= 0 ? (x) : -(x))
#define dabs(x) (fabs(x))
#define f2cmin(a,b) ((a) <= (b) ? (a) : (b))
#define f2cmax(a,b) ((a) >= (b) ? (a) : (b))
#define dmin(a,b) (f2cmin(a,b))
#define dmax(a,b) (f2cmax(a,b))
#define bit_test(a,b) ((a) >> (b) & 1)
#define bit_clear(a,b) ((a) & ~((uinteger)1 << (b)))
#define bit_set(a,b) ((a) | ((uinteger)1 << (b)))
#define abort_() { sig_die("Fortran abort routine called", 1); }
#define c_abs(z) (cabsf(Cf(z)))
#define c_cos(R,Z) { pCf(R)=ccos(Cf(Z)); }
#ifdef _MSC_VER
#define c_div(c, a, b) {Cf(c)._Val[0] = (Cf(a)._Val[0]/Cf(b)._Val[0]); Cf(c)._Val[1]=(Cf(a)._Val[1]/Cf(b)._Val[1]);}
#define z_div(c, a, b) {Cd(c)._Val[0] = (Cd(a)._Val[0]/Cd(b)._Val[0]); Cd(c)._Val[1]=(Cd(a)._Val[1]/df(b)._Val[1]);}
#else
#define c_div(c, a, b) {pCf(c) = Cf(a)/Cf(b);}
#define z_div(c, a, b) {pCd(c) = Cd(a)/Cd(b);}
#endif
#define c_exp(R, Z) {pCf(R) = cexpf(Cf(Z));}
#define c_log(R, Z) {pCf(R) = clogf(Cf(Z));}
#define c_sin(R, Z) {pCf(R) = csinf(Cf(Z));}
//#define c_sqrt(R, Z) {*(R) = csqrtf(Cf(Z));}
#define c_sqrt(R, Z) {pCf(R) = csqrtf(Cf(Z));}
#define d_abs(x) (fabs(*(x)))
#define d_acos(x) (acos(*(x)))
#define d_asin(x) (asin(*(x)))
#define d_atan(x) (atan(*(x)))
#define d_atn2(x, y) (atan2(*(x),*(y)))
#define d_cnjg(R, Z) { pCd(R) = conj(Cd(Z)); }
#define r_cnjg(R, Z) { pCf(R) = conjf(Cf(Z)); }
#define d_cos(x) (cos(*(x)))
#define d_cosh(x) (cosh(*(x)))
#define d_dim(__a, __b) ( *(__a) > *(__b) ? *(__a) - *(__b) : 0.0 )
#define d_exp(x) (exp(*(x)))
#define d_imag(z) (cimag(Cd(z)))
#define r_imag(z) (cimagf(Cf(z)))
#define d_int(__x) (*(__x)>0 ? floor(*(__x)) : -floor(- *(__x)))
#define r_int(__x) (*(__x)>0 ? floor(*(__x)) : -floor(- *(__x)))
#define d_lg10(x) ( 0.43429448190325182765 * log(*(x)) )
#define r_lg10(x) ( 0.43429448190325182765 * log(*(x)) )
#define d_log(x) (log(*(x)))
#define d_mod(x, y) (fmod(*(x), *(y)))
#define u_nint(__x) ((__x)>=0 ? floor((__x) + .5) : -floor(.5 - (__x)))
#define d_nint(x) u_nint(*(x))
#define u_sign(__a,__b) ((__b) >= 0 ? ((__a) >= 0 ? (__a) : -(__a)) : -((__a) >= 0 ? (__a) : -(__a)))
#define d_sign(a,b) u_sign(*(a),*(b))
#define r_sign(a,b) u_sign(*(a),*(b))
#define d_sin(x) (sin(*(x)))
#define d_sinh(x) (sinh(*(x)))
#define d_sqrt(x) (sqrt(*(x)))
#define d_tan(x) (tan(*(x)))
#define d_tanh(x) (tanh(*(x)))
#define i_abs(x) abs(*(x))
#define i_dnnt(x) ((integer)u_nint(*(x)))
#define i_len(s, n) (n)
#define i_nint(x) ((integer)u_nint(*(x)))
#define i_sign(a,b) ((integer)u_sign((integer)*(a),(integer)*(b)))
#define pow_dd(ap, bp) ( pow(*(ap), *(bp)))
#define pow_si(B,E) spow_ui(*(B),*(E))
#define pow_ri(B,E) spow_ui(*(B),*(E))
#define pow_di(B,E) dpow_ui(*(B),*(E))
#define pow_zi(p, a, b) {pCd(p) = zpow_ui(Cd(a), *(b));}
#define pow_ci(p, a, b) {pCf(p) = cpow_ui(Cf(a), *(b));}
#define pow_zz(R,A,B) {pCd(R) = cpow(Cd(A),*(B));}
#define s_cat(lpp, rpp, rnp, np, llp) { ftnlen i, nc, ll; char *f__rp, *lp; ll = (llp); lp = (lpp); for(i=0; i < (int)*(np); ++i) { nc = ll; if((rnp)[i] < nc) nc = (rnp)[i]; ll -= nc; f__rp = (rpp)[i]; while(--nc >= 0) *lp++ = *(f__rp)++; } while(--ll >= 0) *lp++ = ' '; }
#define s_cmp(a,b,c,d) ((integer)strncmp((a),(b),f2cmin((c),(d))))
#define s_copy(A,B,C,D) { int __i,__m; for (__i=0, __m=f2cmin((C),(D)); __i<__m && (B)[__i] != 0; ++__i) (A)[__i] = (B)[__i]; }
#define sig_die(s, kill) { exit(1); }
#define s_stop(s, n) {exit(0);}
static char junk[] = "\n@(#)LIBF77 VERSION 19990503\n";
#define z_abs(z) (cabs(Cd(z)))
#define z_exp(R, Z) {pCd(R) = cexp(Cd(Z));}
#define z_sqrt(R, Z) {pCd(R) = csqrt(Cd(Z));}
#define myexit_() break;
#define mycycle() continue;
#define myceiling(w) {ceil(w)}
#define myhuge(w) {HUGE_VAL}
//#define mymaxloc_(w,s,e,n) {if (sizeof(*(w)) == sizeof(double)) dmaxloc_((w),*(s),*(e),n); else dmaxloc_((w),*(s),*(e),n);}
#define mymaxloc(w,s,e,n) {dmaxloc_(w,*(s),*(e),n)}
/* procedure parameter types for -A and -C++ */
#ifdef __cplusplus
typedef logical (*L_fp)(...);
#else
typedef logical (*L_fp)();
#endif
static float spow_ui(float x, integer n) {
float pow=1.0; unsigned long int u;
if(n != 0) {
if(n < 0) n = -n, x = 1/x;
for(u = n; ; ) {
if(u & 01) pow *= x;
if(u >>= 1) x *= x;
else break;
}
}
return pow;
}
static double dpow_ui(double x, integer n) {
double pow=1.0; unsigned long int u;
if(n != 0) {
if(n < 0) n = -n, x = 1/x;
for(u = n; ; ) {
if(u & 01) pow *= x;
if(u >>= 1) x *= x;
else break;
}
}
return pow;
}
#ifdef _MSC_VER
static _Fcomplex cpow_ui(complex x, integer n) {
complex pow={1.0,0.0}; unsigned long int u;
if(n != 0) {
if(n < 0) n = -n, x.r = 1/x.r, x.i=1/x.i;
for(u = n; ; ) {
if(u & 01) pow.r *= x.r, pow.i *= x.i;
if(u >>= 1) x.r *= x.r, x.i *= x.i;
else break;
}
}
_Fcomplex p={pow.r, pow.i};
return p;
}
#else
static _Complex float cpow_ui(_Complex float x, integer n) {
_Complex float pow=1.0; unsigned long int u;
if(n != 0) {
if(n < 0) n = -n, x = 1/x;
for(u = n; ; ) {
if(u & 01) pow *= x;
if(u >>= 1) x *= x;
else break;
}
}
return pow;
}
#endif
#ifdef _MSC_VER
static _Dcomplex zpow_ui(_Dcomplex x, integer n) {
_Dcomplex pow={1.0,0.0}; unsigned long int u;
if(n != 0) {
if(n < 0) n = -n, x._Val[0] = 1/x._Val[0], x._Val[1] =1/x._Val[1];
for(u = n; ; ) {
if(u & 01) pow._Val[0] *= x._Val[0], pow._Val[1] *= x._Val[1];
if(u >>= 1) x._Val[0] *= x._Val[0], x._Val[1] *= x._Val[1];
else break;
}
}
_Dcomplex p = {pow._Val[0], pow._Val[1]};
return p;
}
#else
static _Complex double zpow_ui(_Complex double x, integer n) {
_Complex double pow=1.0; unsigned long int u;
if(n != 0) {
if(n < 0) n = -n, x = 1/x;
for(u = n; ; ) {
if(u & 01) pow *= x;
if(u >>= 1) x *= x;
else break;
}
}
return pow;
}
#endif
static integer pow_ii(integer x, integer n) {
integer pow; unsigned long int u;
if (n <= 0) {
if (n == 0 || x == 1) pow = 1;
else if (x != -1) pow = x == 0 ? 1/x : 0;
else n = -n;
}
if ((n > 0) || !(n == 0 || x == 1 || x != -1)) {
u = n;
for(pow = 1; ; ) {
if(u & 01) pow *= x;
if(u >>= 1) x *= x;
else break;
}
}
return pow;
}
static integer dmaxloc_(double *w, integer s, integer e, integer *n)
{
double m; integer i, mi;
for(m=w[s-1], mi=s, i=s+1; i<=e; i++)
if (w[i-1]>m) mi=i ,m=w[i-1];
return mi-s+1;
}
static integer smaxloc_(float *w, integer s, integer e, integer *n)
{
float m; integer i, mi;
for(m=w[s-1], mi=s, i=s+1; i<=e; i++)
if (w[i-1]>m) mi=i ,m=w[i-1];
return mi-s+1;
}
static inline void cdotc_(complex *z, integer *n_, complex *x, integer *incx_, complex *y, integer *incy_) {
integer n = *n_, incx = *incx_, incy = *incy_, i;
#ifdef _MSC_VER
_Fcomplex zdotc = {0.0, 0.0};
if (incx == 1 && incy == 1) {
for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
zdotc._Val[0] += conjf(Cf(&x[i]))._Val[0] * Cf(&y[i])._Val[0];
zdotc._Val[1] += conjf(Cf(&x[i]))._Val[1] * Cf(&y[i])._Val[1];
}
} else {
for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
zdotc._Val[0] += conjf(Cf(&x[i*incx]))._Val[0] * Cf(&y[i*incy])._Val[0];
zdotc._Val[1] += conjf(Cf(&x[i*incx]))._Val[1] * Cf(&y[i*incy])._Val[1];
}
}
pCf(z) = zdotc;
}
#else
_Complex float zdotc = 0.0;
if (incx == 1 && incy == 1) {
for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
zdotc += conjf(Cf(&x[i])) * Cf(&y[i]);
}
} else {
for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
zdotc += conjf(Cf(&x[i*incx])) * Cf(&y[i*incy]);
}
}
pCf(z) = zdotc;
}
#endif
static inline void zdotc_(doublecomplex *z, integer *n_, doublecomplex *x, integer *incx_, doublecomplex *y, integer *incy_) {
integer n = *n_, incx = *incx_, incy = *incy_, i;
#ifdef _MSC_VER
_Dcomplex zdotc = {0.0, 0.0};
if (incx == 1 && incy == 1) {
for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
zdotc._Val[0] += conj(Cd(&x[i]))._Val[0] * Cd(&y[i])._Val[0];
zdotc._Val[1] += conj(Cd(&x[i]))._Val[1] * Cd(&y[i])._Val[1];
}
} else {
for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
zdotc._Val[0] += conj(Cd(&x[i*incx]))._Val[0] * Cd(&y[i*incy])._Val[0];
zdotc._Val[1] += conj(Cd(&x[i*incx]))._Val[1] * Cd(&y[i*incy])._Val[1];
}
}
pCd(z) = zdotc;
}
#else
_Complex double zdotc = 0.0;
if (incx == 1 && incy == 1) {
for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
zdotc += conj(Cd(&x[i])) * Cd(&y[i]);
}
} else {
for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
zdotc += conj(Cd(&x[i*incx])) * Cd(&y[i*incy]);
}
}
pCd(z) = zdotc;
}
#endif
static inline void cdotu_(complex *z, integer *n_, complex *x, integer *incx_, complex *y, integer *incy_) {
integer n = *n_, incx = *incx_, incy = *incy_, i;
#ifdef _MSC_VER
_Fcomplex zdotc = {0.0, 0.0};
if (incx == 1 && incy == 1) {
for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
zdotc._Val[0] += Cf(&x[i])._Val[0] * Cf(&y[i])._Val[0];
zdotc._Val[1] += Cf(&x[i])._Val[1] * Cf(&y[i])._Val[1];
}
} else {
for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
zdotc._Val[0] += Cf(&x[i*incx])._Val[0] * Cf(&y[i*incy])._Val[0];
zdotc._Val[1] += Cf(&x[i*incx])._Val[1] * Cf(&y[i*incy])._Val[1];
}
}
pCf(z) = zdotc;
}
#else
_Complex float zdotc = 0.0;
if (incx == 1 && incy == 1) {
for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
zdotc += Cf(&x[i]) * Cf(&y[i]);
}
} else {
for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
zdotc += Cf(&x[i*incx]) * Cf(&y[i*incy]);
}
}
pCf(z) = zdotc;
}
#endif
static inline void zdotu_(doublecomplex *z, integer *n_, doublecomplex *x, integer *incx_, doublecomplex *y, integer *incy_) {
integer n = *n_, incx = *incx_, incy = *incy_, i;
#ifdef _MSC_VER
_Dcomplex zdotc = {0.0, 0.0};
if (incx == 1 && incy == 1) {
for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
zdotc._Val[0] += Cd(&x[i])._Val[0] * Cd(&y[i])._Val[0];
zdotc._Val[1] += Cd(&x[i])._Val[1] * Cd(&y[i])._Val[1];
}
} else {
for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
zdotc._Val[0] += Cd(&x[i*incx])._Val[0] * Cd(&y[i*incy])._Val[0];
zdotc._Val[1] += Cd(&x[i*incx])._Val[1] * Cd(&y[i*incy])._Val[1];
}
}
pCd(z) = zdotc;
}
#else
_Complex double zdotc = 0.0;
if (incx == 1 && incy == 1) {
for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
zdotc += Cd(&x[i]) * Cd(&y[i]);
}
} else {
for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
zdotc += Cd(&x[i*incx]) * Cd(&y[i*incy]);
}
}
pCd(z) = zdotc;
}
#endif
/* -- translated by f2c (version 20000121).
You must link the resulting object file with the libraries:
-lf2c -lm (in that order)
*/
/* > \brief \b SLARRB provides limited bisection to locate eigenvalues for more accuracy. */
/* =========== DOCUMENTATION =========== */
/* Online html documentation available at */
/* http://www.netlib.org/lapack/explore-html/ */
/* > \htmlonly */
/* > Download SLARRB + dependencies */
/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/slarrb.
f"> */
/* > [TGZ]</a> */
/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/slarrb.
f"> */
/* > [ZIP]</a> */
/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/slarrb.
f"> */
/* > [TXT]</a> */
/* > \endhtmlonly */
/* Definition: */
/* =========== */
/* SUBROUTINE SLARRB( N, D, LLD, IFIRST, ILAST, RTOL1, */
/* RTOL2, OFFSET, W, WGAP, WERR, WORK, IWORK, */
/* PIVMIN, SPDIAM, TWIST, INFO ) */
/* INTEGER IFIRST, ILAST, INFO, N, OFFSET, TWIST */
/* REAL PIVMIN, RTOL1, RTOL2, SPDIAM */
/* INTEGER IWORK( * ) */
/* REAL D( * ), LLD( * ), W( * ), */
/* $ WERR( * ), WGAP( * ), WORK( * ) */
/* > \par Purpose: */
/* ============= */
/* > */
/* > \verbatim */
/* > */
/* > Given the relatively robust representation(RRR) L D L^T, SLARRB */
/* > does "limited" bisection to refine the eigenvalues of L D L^T, */
/* > W( IFIRST-OFFSET ) through W( ILAST-OFFSET ), to more accuracy. Initial */
/* > guesses for these eigenvalues are input in W, the corresponding estimate */
/* > of the error in these guesses and their gaps are input in WERR */
/* > and WGAP, respectively. During bisection, intervals */
/* > [left, right] are maintained by storing their mid-points and */
/* > semi-widths in the arrays W and WERR respectively. */
/* > \endverbatim */
/* Arguments: */
/* ========== */
/* > \param[in] N */
/* > \verbatim */
/* > N is INTEGER */
/* > The order of the matrix. */
/* > \endverbatim */
/* > */
/* > \param[in] D */
/* > \verbatim */
/* > D is REAL array, dimension (N) */
/* > The N diagonal elements of the diagonal matrix D. */
/* > \endverbatim */
/* > */
/* > \param[in] LLD */
/* > \verbatim */
/* > LLD is REAL array, dimension (N-1) */
/* > The (N-1) elements L(i)*L(i)*D(i). */
/* > \endverbatim */
/* > */
/* > \param[in] IFIRST */
/* > \verbatim */
/* > IFIRST is INTEGER */
/* > The index of the first eigenvalue to be computed. */
/* > \endverbatim */
/* > */
/* > \param[in] ILAST */
/* > \verbatim */
/* > ILAST is INTEGER */
/* > The index of the last eigenvalue to be computed. */
/* > \endverbatim */
/* > */
/* > \param[in] RTOL1 */
/* > \verbatim */
/* > RTOL1 is REAL */
/* > \endverbatim */
/* > */
/* > \param[in] RTOL2 */
/* > \verbatim */
/* > RTOL2 is REAL */
/* > Tolerance for the convergence of the bisection intervals. */
/* > An interval [LEFT,RIGHT] has converged if */
/* > RIGHT-LEFT < MAX( RTOL1*GAP, RTOL2*MAX(|LEFT|,|RIGHT|) ) */
/* > where GAP is the (estimated) distance to the nearest */
/* > eigenvalue. */
/* > \endverbatim */
/* > */
/* > \param[in] OFFSET */
/* > \verbatim */
/* > OFFSET is INTEGER */
/* > Offset for the arrays W, WGAP and WERR, i.e., the IFIRST-OFFSET */
/* > through ILAST-OFFSET elements of these arrays are to be used. */
/* > \endverbatim */
/* > */
/* > \param[in,out] W */
/* > \verbatim */
/* > W is REAL array, dimension (N) */
/* > On input, W( IFIRST-OFFSET ) through W( ILAST-OFFSET ) are */
/* > estimates of the eigenvalues of L D L^T indexed IFIRST through */
/* > ILAST. */
/* > On output, these estimates are refined. */
/* > \endverbatim */
/* > */
/* > \param[in,out] WGAP */
/* > \verbatim */
/* > WGAP is REAL array, dimension (N-1) */
/* > On input, the (estimated) gaps between consecutive */
/* > eigenvalues of L D L^T, i.e., WGAP(I-OFFSET) is the gap between */
/* > eigenvalues I and I+1. Note that if IFIRST = ILAST */
/* > then WGAP(IFIRST-OFFSET) must be set to ZERO. */
/* > On output, these gaps are refined. */
/* > \endverbatim */
/* > */
/* > \param[in,out] WERR */
/* > \verbatim */
/* > WERR is REAL array, dimension (N) */
/* > On input, WERR( IFIRST-OFFSET ) through WERR( ILAST-OFFSET ) are */
/* > the errors in the estimates of the corresponding elements in W. */
/* > On output, these errors are refined. */
/* > \endverbatim */
/* > */
/* > \param[out] WORK */
/* > \verbatim */
/* > WORK is REAL array, dimension (2*N) */
/* > Workspace. */
/* > \endverbatim */
/* > */
/* > \param[out] IWORK */
/* > \verbatim */
/* > IWORK is INTEGER array, dimension (2*N) */
/* > Workspace. */
/* > \endverbatim */
/* > */
/* > \param[in] PIVMIN */
/* > \verbatim */
/* > PIVMIN is REAL */
/* > The minimum pivot in the Sturm sequence. */
/* > \endverbatim */
/* > */
/* > \param[in] SPDIAM */
/* > \verbatim */
/* > SPDIAM is REAL */
/* > The spectral diameter of the matrix. */
/* > \endverbatim */
/* > */
/* > \param[in] TWIST */
/* > \verbatim */
/* > TWIST is INTEGER */
/* > The twist index for the twisted factorization that is used */
/* > for the negcount. */
/* > TWIST = N: Compute negcount from L D L^T - LAMBDA I = L+ D+ L+^T */
/* > TWIST = 1: Compute negcount from L D L^T - LAMBDA I = U- D- U-^T */
/* > TWIST = R: Compute negcount from L D L^T - LAMBDA I = N(r) D(r) N(r) */
/* > \endverbatim */
/* > */
/* > \param[out] INFO */
/* > \verbatim */
/* > INFO is INTEGER */
/* > Error flag. */
/* > \endverbatim */
/* Authors: */
/* ======== */
/* > \author Univ. of Tennessee */
/* > \author Univ. of California Berkeley */
/* > \author Univ. of Colorado Denver */
/* > \author NAG Ltd. */
/* > \date June 2017 */
/* > \ingroup OTHERauxiliary */
/* > \par Contributors: */
/* ================== */
/* > */
/* > Beresford Parlett, University of California, Berkeley, USA \n */
/* > Jim Demmel, University of California, Berkeley, USA \n */
/* > Inderjit Dhillon, University of Texas, Austin, USA \n */
/* > Osni Marques, LBNL/NERSC, USA \n */
/* > Christof Voemel, University of California, Berkeley, USA */
/* ===================================================================== */
/* Subroutine */ void slarrb_(integer *n, real *d__, real *lld, integer *
ifirst, integer *ilast, real *rtol1, real *rtol2, integer *offset,
real *w, real *wgap, real *werr, real *work, integer *iwork, real *
pivmin, real *spdiam, integer *twist, integer *info)
{
/* System generated locals */
integer i__1;
real r__1, r__2;
/* Local variables */
real back, lgap, rgap, left;
integer iter, nint, prev, next, i__, k, r__;
real cvrgd, right, width;
integer i1, ii, ip;
extern integer slaneg_(integer *, real *, real *, real *, real *, integer
*);
integer negcnt;
real mnwdth;
integer olnint, maxitr;
real gap, mid, tmp;
/* -- LAPACK auxiliary routine (version 3.7.1) -- */
/* -- LAPACK is a software package provided by Univ. of Tennessee, -- */
/* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- */
/* June 2017 */
/* ===================================================================== */
/* Parameter adjustments */
--iwork;
--work;
--werr;
--wgap;
--w;
--lld;
--d__;
/* Function Body */
*info = 0;
/* Quick return if possible */
if (*n <= 0) {
return;
}
maxitr = (integer) ((log(*spdiam + *pivmin) - log(*pivmin)) / log(2.f)) +
2;
mnwdth = *pivmin * 2.f;
r__ = *twist;
if (r__ < 1 || r__ > *n) {
r__ = *n;
}
/* Initialize unconverged intervals in [ WORK(2*I-1), WORK(2*I) ]. */
/* The Sturm Count, Count( WORK(2*I-1) ) is arranged to be I-1, while */
/* Count( WORK(2*I) ) is stored in IWORK( 2*I ). The integer IWORK( 2*I-1 ) */
/* for an unconverged interval is set to the index of the next unconverged */
/* interval, and is -1 or 0 for a converged interval. Thus a linked */
/* list of unconverged intervals is set up. */
i1 = *ifirst;
/* The number of unconverged intervals */
nint = 0;
/* The last unconverged interval found */
prev = 0;
rgap = wgap[i1 - *offset];
i__1 = *ilast;
for (i__ = i1; i__ <= i__1; ++i__) {
k = i__ << 1;
ii = i__ - *offset;
left = w[ii] - werr[ii];
right = w[ii] + werr[ii];
lgap = rgap;
rgap = wgap[ii];
gap = f2cmin(lgap,rgap);
/* Make sure that [LEFT,RIGHT] contains the desired eigenvalue */
/* Compute negcount from dstqds facto L+D+L+^T = L D L^T - LEFT */
/* Do while( NEGCNT(LEFT).GT.I-1 ) */
back = werr[ii];
L20:
negcnt = slaneg_(n, &d__[1], &lld[1], &left, pivmin, &r__);
if (negcnt > i__ - 1) {
left -= back;
back *= 2.f;
goto L20;
}
/* Do while( NEGCNT(RIGHT).LT.I ) */
/* Compute negcount from dstqds facto L+D+L+^T = L D L^T - RIGHT */
back = werr[ii];
L50:
negcnt = slaneg_(n, &d__[1], &lld[1], &right, pivmin, &r__);
if (negcnt < i__) {
right += back;
back *= 2.f;
goto L50;
}
width = (r__1 = left - right, abs(r__1)) * .5f;
/* Computing MAX */
r__1 = abs(left), r__2 = abs(right);
tmp = f2cmax(r__1,r__2);
/* Computing MAX */
r__1 = *rtol1 * gap, r__2 = *rtol2 * tmp;
cvrgd = f2cmax(r__1,r__2);
if (width <= cvrgd || width <= mnwdth) {
/* This interval has already converged and does not need refinement. */
/* (Note that the gaps might change through refining the */
/* eigenvalues, however, they can only get bigger.) */
/* Remove it from the list. */
iwork[k - 1] = -1;
/* Make sure that I1 always points to the first unconverged interval */
if (i__ == i1 && i__ < *ilast) {
i1 = i__ + 1;
}
if (prev >= i1 && i__ <= *ilast) {
iwork[(prev << 1) - 1] = i__ + 1;
}
} else {
/* unconverged interval found */
prev = i__;
++nint;
iwork[k - 1] = i__ + 1;
iwork[k] = negcnt;
}
work[k - 1] = left;
work[k] = right;
/* L75: */
}
/* Do while( NINT.GT.0 ), i.e. there are still unconverged intervals */
/* and while (ITER.LT.MAXITR) */
iter = 0;
L80:
prev = i1 - 1;
i__ = i1;
olnint = nint;
i__1 = olnint;
for (ip = 1; ip <= i__1; ++ip) {
k = i__ << 1;
ii = i__ - *offset;
rgap = wgap[ii];
lgap = rgap;
if (ii > 1) {
lgap = wgap[ii - 1];
}
gap = f2cmin(lgap,rgap);
next = iwork[k - 1];
left = work[k - 1];
right = work[k];
mid = (left + right) * .5f;
/* semiwidth of interval */
width = right - mid;
/* Computing MAX */
r__1 = abs(left), r__2 = abs(right);
tmp = f2cmax(r__1,r__2);
/* Computing MAX */
r__1 = *rtol1 * gap, r__2 = *rtol2 * tmp;
cvrgd = f2cmax(r__1,r__2);
if (width <= cvrgd || width <= mnwdth || iter == maxitr) {
/* reduce number of unconverged intervals */
--nint;
/* Mark interval as converged. */
iwork[k - 1] = 0;
if (i1 == i__) {
i1 = next;
} else {
/* Prev holds the last unconverged interval previously examined */
if (prev >= i1) {
iwork[(prev << 1) - 1] = next;
}
}
i__ = next;
goto L100;
}
prev = i__;
/* Perform one bisection step */
negcnt = slaneg_(n, &d__[1], &lld[1], &mid, pivmin, &r__);
if (negcnt <= i__ - 1) {
work[k - 1] = mid;
} else {
work[k] = mid;
}
i__ = next;
L100:
;
}
++iter;
/* do another loop if there are still unconverged intervals */
/* However, in the last iteration, all intervals are accepted */
/* since this is the best we can do. */
if (nint > 0 && iter <= maxitr) {
goto L80;
}
/* At this point, all the intervals have converged */
i__1 = *ilast;
for (i__ = *ifirst; i__ <= i__1; ++i__) {
k = i__ << 1;
ii = i__ - *offset;
/* All intervals marked by '0' have been refined. */
if (iwork[k - 1] == 0) {
w[ii] = (work[k - 1] + work[k]) * .5f;
werr[ii] = work[k] - w[ii];
}
/* L110: */
}
i__1 = *ilast;
for (i__ = *ifirst + 1; i__ <= i__1; ++i__) {
k = i__ << 1;
ii = i__ - *offset;
/* Computing MAX */
r__1 = 0.f, r__2 = w[ii] - werr[ii] - w[ii - 1] - werr[ii - 1];
wgap[ii - 1] = f2cmax(r__1,r__2);
/* L111: */
}
return;
/* End of SLARRB */
} /* slarrb_ */