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/* arpack/dsgets.f -- translated by f2c (version 20090411).
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
*/
#ifdef __cplusplus
extern "C" {
#endif
#include "v3p_netlib.h"
/* Common Block Declarations */
/*Extern struct { */
/* integer logfil, ndigit, mgetv0, msaupd, msaup2, msaitr, mseigt, msapps, */
/* msgets, mseupd, mnaupd, mnaup2, mnaitr, mneigh, mnapps, mngets, */
/* mneupd, mcaupd, mcaup2, mcaitr, mceigh, mcapps, mcgets, mceupd; */
/*} debug_; */
/*#define debug_1 debug_ */
/*Extern struct { */
/* integer nopx, nbx, nrorth, nitref, nrstrt; */
/* real tsaupd, tsaup2, tsaitr, tseigt, tsgets, tsapps, tsconv, tnaupd, */
/* tnaup2, tnaitr, tneigh, tngets, tnapps, tnconv, tcaupd, tcaup2, */
/* tcaitr, tceigh, tcgets, tcapps, tcconv, tmvopx, tmvbx, tgetv0, */
/* titref, trvec; */
/*} timing_; */
/*#define timing_1 timing_ */
/* Table of constant values */
static logical c_true = TRUE_;
static integer c__1 = 1;
/* ----------------------------------------------------------------------- */
/* \BeginDoc */
/* \Name: dsgets */
/* \Description: */
/* Given the eigenvalues of the symmetric tridiagonal matrix H, */
/* computes the NP shifts AMU that are zeros of the polynomial of */
/* degree NP which filters out components of the unwanted eigenvectors */
/* corresponding to the AMU's based on some given criteria. */
/* NOTE: This is called even in the case of user specified shifts in */
/* order to sort the eigenvalues, and error bounds of H for later use. */
/* \Usage: */
/* call dsgets */
/* ( ISHIFT, WHICH, KEV, NP, RITZ, BOUNDS, SHIFTS ) */
/* \Arguments */
/* ISHIFT Integer. (INPUT) */
/* Method for selecting the implicit shifts at each iteration. */
/* ISHIFT = 0: user specified shifts */
/* ISHIFT = 1: exact shift with respect to the matrix H. */
/* WHICH Character*2. (INPUT) */
/* Shift selection criteria. */
/* 'LM' -> KEV eigenvalues of largest magnitude are retained. */
/* 'SM' -> KEV eigenvalues of smallest magnitude are retained. */
/* 'LA' -> KEV eigenvalues of largest value are retained. */
/* 'SA' -> KEV eigenvalues of smallest value are retained. */
/* 'BE' -> KEV eigenvalues, half from each end of the spectrum. */
/* If KEV is odd, compute one more from the high end. */
/* KEV Integer. (INPUT) */
/* KEV+NP is the size of the matrix H. */
/* NP Integer. (INPUT) */
/* Number of implicit shifts to be computed. */
/* RITZ Double precision array of length KEV+NP. (INPUT/OUTPUT) */
/* On INPUT, RITZ contains the eigenvalues of H. */
/* On OUTPUT, RITZ are sorted so that the unwanted eigenvalues */
/* are in the first NP locations and the wanted part is in */
/* the last KEV locations. When exact shifts are selected, the */
/* unwanted part corresponds to the shifts to be applied. */
/* BOUNDS Double precision array of length KEV+NP. (INPUT/OUTPUT) */
/* Error bounds corresponding to the ordering in RITZ. */
/* SHIFTS Double precision array of length NP. (INPUT/OUTPUT) */
/* On INPUT: contains the user specified shifts if ISHIFT = 0. */
/* On OUTPUT: contains the shifts sorted into decreasing order */
/* of magnitude with respect to the Ritz estimates contained in */
/* BOUNDS. If ISHIFT = 0, SHIFTS is not modified on exit. */
/* \EndDoc */
/* ----------------------------------------------------------------------- */
/* \BeginLib */
/* \Local variables: */
/* xxxxxx real */
/* \Routines called: */
/* dsortr ARPACK utility sorting routine. */
/* second ARPACK utility routine for timing. */
/* dcopy Level 1 BLAS that copies one vector to another. */
/* dswap Level 1 BLAS that swaps the contents of two vectors. */
/* \Author */
/* Danny Sorensen Phuong Vu */
/* Richard Lehoucq CRPC / Rice University */
/* Dept. of Computational & Houston, Texas */
/* Applied Mathematics */
/* Rice University */
/* Houston, Texas */
/* \Revision history: */
/* xx/xx/93: Version ' 2.1' */
/* \SCCS Information: @(#) */
/* FILE: sgets.F SID: 2.4 DATE OF SID: 4/19/96 RELEASE: 2 */
/* \Remarks */
/* \EndLib */
/* ----------------------------------------------------------------------- */
/*< subroutine dsgets ( ishift, which, kev, np, ritz, bounds, shifts ) >*/
/* Subroutine */ int dsgets_(integer *ishift, char *which, integer *kev,
integer *np, doublereal *ritz, doublereal *bounds, doublereal *shifts,
ftnlen which_len)
{
/* System generated locals */
integer i__1;
/* Builtin functions */
integer s_cmp(char *, char *, ftnlen, ftnlen);
/* Local variables */
/* static real t0, t1; */
integer kevd2;
extern /* Subroutine */ int dswap_(integer *, doublereal *, integer *,
doublereal *, integer *), dcopy_(integer *, doublereal *, integer
*, doublereal *, integer *), second_(real *);
/* integer msglvl; */
extern /* Subroutine */ int dsortr_(char *, logical *, integer *,
doublereal *, doublereal *, ftnlen);
/* %----------------------------------------------------% */
/* | Include files for debugging and timing information | */
/* %----------------------------------------------------% */
/*< include 'debug.h' >*/
/*< include 'stat.h' >*/
/* \SCCS Information: @(#) */
/* FILE: debug.h SID: 2.3 DATE OF SID: 11/16/95 RELEASE: 2 */
/* %---------------------------------% */
/* | See debug.doc for documentation | */
/* %---------------------------------% */
/*< >*/
/*< character*2 which >*/
/* %------------------% */
/* | Scalar Arguments | */
/* %------------------% */
/* %--------------------------------% */
/* | See stat.doc for documentation | */
/* %--------------------------------% */
/* \SCCS Information: @(#) */
/* FILE: stat.h SID: 2.2 DATE OF SID: 11/16/95 RELEASE: 2 */
/*< save t0, t1, t2, t3, t4, t5 >*/
/*< integer nopx, nbx, nrorth, nitref, nrstrt >*/
/*< >*/
/*< >*/
/*< integer ishift, kev, np >*/
/* %-----------------% */
/* | Array Arguments | */
/* %-----------------% */
/*< >*/
/* %------------% */
/* | Parameters | */
/* %------------% */
/*< >*/
/*< parameter (one = 1.0D+0, zero = 0.0D+0) >*/
/* %---------------% */
/* | Local Scalars | */
/* %---------------% */
/*< integer kevd2, msglvl >*/
/* %----------------------% */
/* | External Subroutines | */
/* %----------------------% */
/*< external dswap, dcopy, dsortr, second >*/
/* %---------------------% */
/* | Intrinsic Functions | */
/* %---------------------% */
/*< intrinsic max, min >*/
/* %-----------------------% */
/* | Executable Statements | */
/* %-----------------------% */
/* %-------------------------------% */
/* | Initialize timing statistics | */
/* | & message level for debugging | */
/* %-------------------------------% */
/*< call second (t0) >*/
/* Parameter adjustments */
--shifts;
--bounds;
--ritz;
/* Function Body */
/* second_(&t0); */
/*< msglvl = msgets >*/
/* msglvl = debug_1.msgets; */
/*< if (which .eq. 'BE') then >*/
if (s_cmp(which, "BE", (ftnlen)2, (ftnlen)2) == 0) {
/* %-----------------------------------------------------% */
/* | Both ends of the spectrum are requested. | */
/* | Sort the eigenvalues into algebraically increasing | */
/* | order first then swap high end of the spectrum next | */
/* | to low end in appropriate locations. | */
/* | NOTE: when np < floor(kev/2) be careful not to swap | */
/* | overlapping locations. | */
/* %-----------------------------------------------------% */
/*< call dsortr ('LA', .true., kev+np, ritz, bounds) >*/
i__1 = *kev + *np;
dsortr_("LA", &c_true, &i__1, &ritz[1], &bounds[1], (ftnlen)2);
/*< kevd2 = kev / 2 >*/
kevd2 = *kev / 2;
/*< if ( kev .gt. 1 ) then >*/
if (*kev > 1) {
/*< >*/
i__1 = min(kevd2,*np);
dswap_(&i__1, &ritz[1], &c__1, &ritz[max(kevd2,*np) + 1], &c__1);
/*< >*/
i__1 = min(kevd2,*np);
dswap_(&i__1, &bounds[1], &c__1, &bounds[max(kevd2,*np) + 1], &
c__1);
/*< end if >*/
}
/*< else >*/
} else {
/* %----------------------------------------------------% */
/* | LM, SM, LA, SA case. | */
/* | Sort the eigenvalues of H into the desired order | */
/* | and apply the resulting order to BOUNDS. | */
/* | The eigenvalues are sorted so that the wanted part | */
/* | are always in the last KEV locations. | */
/* %----------------------------------------------------% */
/*< call dsortr (which, .true., kev+np, ritz, bounds) >*/
i__1 = *kev + *np;
dsortr_(which, &c_true, &i__1, &ritz[1], &bounds[1], (ftnlen)2);
/*< end if >*/
}
/*< if (ishift .eq. 1 .and. np .gt. 0) then >*/
if (*ishift == 1 && *np > 0) {
/* %-------------------------------------------------------% */
/* | Sort the unwanted Ritz values used as shifts so that | */
/* | the ones with largest Ritz estimates are first. | */
/* | This will tend to minimize the effects of the | */
/* | forward instability of the iteration when the shifts | */
/* | are applied in subroutine dsapps. | */
/* %-------------------------------------------------------% */
/*< call dsortr ('SM', .true., np, bounds, ritz) >*/
dsortr_("SM", &c_true, np, &bounds[1], &ritz[1], (ftnlen)2);
/*< call dcopy (np, ritz, 1, shifts, 1) >*/
dcopy_(np, &ritz[1], &c__1, &shifts[1], &c__1);
/*< end if >*/
}
/*< call second (t1) >*/
/* second_(&t1); */
/*< tsgets = tsgets + (t1 - t0) >*/
/* timing_1.tsgets += t1 - t0; */
/* if (msglvl .gt. 0) then */
/* call ivout (logfil, 1, kev, ndigit, '_sgets: KEV is') */
/* call ivout (logfil, 1, np, ndigit, '_sgets: NP is') */
/* call dvout (logfil, kev+np, ritz, ndigit, */
/* & '_sgets: Eigenvalues of current H matrix') */
/* call dvout (logfil, kev+np, bounds, ndigit, */
/* & '_sgets: Associated Ritz estimates') */
/* end if */
/*< return >*/
return 0;
/* %---------------% */
/* | End of dsgets | */
/* %---------------% */
/*< end >*/
} /* dsgets_ */
#ifdef __cplusplus
}
#endif
|
