184 lines
4.6 KiB
C
184 lines
4.6 KiB
C
/* dlarrc.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 "clapack.h"
|
|
|
|
|
|
/* Subroutine */ int dlarrc_(char *jobt, integer *n, doublereal *vl,
|
|
doublereal *vu, doublereal *d__, doublereal *e, doublereal *pivmin,
|
|
integer *eigcnt, integer *lcnt, integer *rcnt, integer *info)
|
|
{
|
|
/* System generated locals */
|
|
integer i__1;
|
|
doublereal d__1;
|
|
|
|
/* Local variables */
|
|
integer i__;
|
|
doublereal sl, su, tmp, tmp2;
|
|
logical matt;
|
|
extern logical lsame_(char *, char *);
|
|
doublereal lpivot, rpivot;
|
|
|
|
|
|
/* -- LAPACK auxiliary routine (version 3.2) -- */
|
|
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
|
|
/* November 2006 */
|
|
|
|
/* .. Scalar Arguments .. */
|
|
/* .. */
|
|
/* .. Array Arguments .. */
|
|
/* .. */
|
|
|
|
/* Purpose */
|
|
/* ======= */
|
|
|
|
/* Find the number of eigenvalues of the symmetric tridiagonal matrix T */
|
|
/* that are in the interval (VL,VU] if JOBT = 'T', and of L D L^T */
|
|
/* if JOBT = 'L'. */
|
|
|
|
/* Arguments */
|
|
/* ========= */
|
|
|
|
/* JOBT (input) CHARACTER*1 */
|
|
/* = 'T': Compute Sturm count for matrix T. */
|
|
/* = 'L': Compute Sturm count for matrix L D L^T. */
|
|
|
|
/* N (input) INTEGER */
|
|
/* The order of the matrix. N > 0. */
|
|
|
|
/* VL (input) DOUBLE PRECISION */
|
|
/* VU (input) DOUBLE PRECISION */
|
|
/* The lower and upper bounds for the eigenvalues. */
|
|
|
|
/* D (input) DOUBLE PRECISION array, dimension (N) */
|
|
/* JOBT = 'T': The N diagonal elements of the tridiagonal matrix T. */
|
|
/* JOBT = 'L': The N diagonal elements of the diagonal matrix D. */
|
|
|
|
/* E (input) DOUBLE PRECISION array, dimension (N) */
|
|
/* JOBT = 'T': The N-1 offdiagonal elements of the matrix T. */
|
|
/* JOBT = 'L': The N-1 offdiagonal elements of the matrix L. */
|
|
|
|
/* PIVMIN (input) DOUBLE PRECISION */
|
|
/* The minimum pivot in the Sturm sequence for T. */
|
|
|
|
/* EIGCNT (output) INTEGER */
|
|
/* The number of eigenvalues of the symmetric tridiagonal matrix T */
|
|
/* that are in the interval (VL,VU] */
|
|
|
|
/* LCNT (output) INTEGER */
|
|
/* RCNT (output) INTEGER */
|
|
/* The left and right negcounts of the interval. */
|
|
|
|
/* INFO (output) INTEGER */
|
|
|
|
/* Further Details */
|
|
/* =============== */
|
|
|
|
/* Based on contributions by */
|
|
/* Beresford Parlett, University of California, Berkeley, USA */
|
|
/* Jim Demmel, University of California, Berkeley, USA */
|
|
/* Inderjit Dhillon, University of Texas, Austin, USA */
|
|
/* Osni Marques, LBNL/NERSC, USA */
|
|
/* Christof Voemel, University of California, Berkeley, USA */
|
|
|
|
/* ===================================================================== */
|
|
|
|
/* .. Parameters .. */
|
|
/* .. */
|
|
/* .. Local Scalars .. */
|
|
/* .. */
|
|
/* .. External Functions .. */
|
|
/* .. */
|
|
/* .. Executable Statements .. */
|
|
|
|
/* Parameter adjustments */
|
|
--e;
|
|
--d__;
|
|
|
|
/* Function Body */
|
|
*info = 0;
|
|
*lcnt = 0;
|
|
*rcnt = 0;
|
|
*eigcnt = 0;
|
|
matt = lsame_(jobt, "T");
|
|
if (matt) {
|
|
/* Sturm sequence count on T */
|
|
lpivot = d__[1] - *vl;
|
|
rpivot = d__[1] - *vu;
|
|
if (lpivot <= 0.) {
|
|
++(*lcnt);
|
|
}
|
|
if (rpivot <= 0.) {
|
|
++(*rcnt);
|
|
}
|
|
i__1 = *n - 1;
|
|
for (i__ = 1; i__ <= i__1; ++i__) {
|
|
/* Computing 2nd power */
|
|
d__1 = e[i__];
|
|
tmp = d__1 * d__1;
|
|
lpivot = d__[i__ + 1] - *vl - tmp / lpivot;
|
|
rpivot = d__[i__ + 1] - *vu - tmp / rpivot;
|
|
if (lpivot <= 0.) {
|
|
++(*lcnt);
|
|
}
|
|
if (rpivot <= 0.) {
|
|
++(*rcnt);
|
|
}
|
|
/* L10: */
|
|
}
|
|
} else {
|
|
/* Sturm sequence count on L D L^T */
|
|
sl = -(*vl);
|
|
su = -(*vu);
|
|
i__1 = *n - 1;
|
|
for (i__ = 1; i__ <= i__1; ++i__) {
|
|
lpivot = d__[i__] + sl;
|
|
rpivot = d__[i__] + su;
|
|
if (lpivot <= 0.) {
|
|
++(*lcnt);
|
|
}
|
|
if (rpivot <= 0.) {
|
|
++(*rcnt);
|
|
}
|
|
tmp = e[i__] * d__[i__] * e[i__];
|
|
|
|
tmp2 = tmp / lpivot;
|
|
if (tmp2 == 0.) {
|
|
sl = tmp - *vl;
|
|
} else {
|
|
sl = sl * tmp2 - *vl;
|
|
}
|
|
|
|
tmp2 = tmp / rpivot;
|
|
if (tmp2 == 0.) {
|
|
su = tmp - *vu;
|
|
} else {
|
|
su = su * tmp2 - *vu;
|
|
}
|
|
/* L20: */
|
|
}
|
|
lpivot = d__[*n] + sl;
|
|
rpivot = d__[*n] + su;
|
|
if (lpivot <= 0.) {
|
|
++(*lcnt);
|
|
}
|
|
if (rpivot <= 0.) {
|
|
++(*rcnt);
|
|
}
|
|
}
|
|
*eigcnt = *rcnt - *lcnt;
|
|
return 0;
|
|
|
|
/* end of DLARRC */
|
|
|
|
} /* dlarrc_ */
|