283 lines
10 KiB
C
283 lines
10 KiB
C
/* iparmq.f -- translated by f2c (version 20061008).
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You must link the resulting object file with libf2c:
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on Microsoft Windows system, link with libf2c.lib;
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on Linux or Unix systems, link with .../path/to/libf2c.a -lm
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or, if you install libf2c.a in a standard place, with -lf2c -lm
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-- in that order, at the end of the command line, as in
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cc *.o -lf2c -lm
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Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
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http://www.netlib.org/f2c/libf2c.zip
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*/
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#include "clapack.h"
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integer iparmq_(integer *ispec, char *name__, char *opts, integer *n, integer
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*ilo, integer *ihi, integer *lwork)
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{
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/* System generated locals */
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integer ret_val, i__1, i__2;
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real r__1;
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/* Builtin functions */
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double log(doublereal);
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integer i_nint(real *);
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/* Local variables */
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integer nh, ns;
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/* -- LAPACK auxiliary routine (version 3.2) -- */
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/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
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/* November 2006 */
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/* .. Scalar Arguments .. */
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/* Purpose */
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/* ======= */
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/* This program sets problem and machine dependent parameters */
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/* useful for xHSEQR and its subroutines. It is called whenever */
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/* ILAENV is called with 12 <= ISPEC <= 16 */
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/* Arguments */
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/* ========= */
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/* ISPEC (input) integer scalar */
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/* ISPEC specifies which tunable parameter IPARMQ should */
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/* return. */
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/* ISPEC=12: (INMIN) Matrices of order nmin or less */
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/* are sent directly to xLAHQR, the implicit */
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/* double shift QR algorithm. NMIN must be */
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/* at least 11. */
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/* ISPEC=13: (INWIN) Size of the deflation window. */
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/* This is best set greater than or equal to */
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/* the number of simultaneous shifts NS. */
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/* Larger matrices benefit from larger deflation */
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/* windows. */
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/* ISPEC=14: (INIBL) Determines when to stop nibbling and */
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/* invest in an (expensive) multi-shift QR sweep. */
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/* If the aggressive early deflation subroutine */
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/* finds LD converged eigenvalues from an order */
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/* NW deflation window and LD.GT.(NW*NIBBLE)/100, */
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/* then the next QR sweep is skipped and early */
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/* deflation is applied immediately to the */
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/* remaining active diagonal block. Setting */
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/* IPARMQ(ISPEC=14) = 0 causes TTQRE to skip a */
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/* multi-shift QR sweep whenever early deflation */
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/* finds a converged eigenvalue. Setting */
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/* IPARMQ(ISPEC=14) greater than or equal to 100 */
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/* prevents TTQRE from skipping a multi-shift */
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/* QR sweep. */
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/* ISPEC=15: (NSHFTS) The number of simultaneous shifts in */
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/* a multi-shift QR iteration. */
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/* ISPEC=16: (IACC22) IPARMQ is set to 0, 1 or 2 with the */
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/* following meanings. */
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/* 0: During the multi-shift QR sweep, */
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/* xLAQR5 does not accumulate reflections and */
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/* does not use matrix-matrix multiply to */
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/* update the far-from-diagonal matrix */
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/* entries. */
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/* 1: During the multi-shift QR sweep, */
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/* xLAQR5 and/or xLAQRaccumulates reflections and uses */
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/* matrix-matrix multiply to update the */
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/* far-from-diagonal matrix entries. */
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/* 2: During the multi-shift QR sweep. */
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/* xLAQR5 accumulates reflections and takes */
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/* advantage of 2-by-2 block structure during */
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/* matrix-matrix multiplies. */
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/* (If xTRMM is slower than xGEMM, then */
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/* IPARMQ(ISPEC=16)=1 may be more efficient than */
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/* IPARMQ(ISPEC=16)=2 despite the greater level of */
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/* arithmetic work implied by the latter choice.) */
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/* NAME (input) character string */
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/* Name of the calling subroutine */
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/* OPTS (input) character string */
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/* This is a concatenation of the string arguments to */
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/* TTQRE. */
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/* N (input) integer scalar */
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/* N is the order of the Hessenberg matrix H. */
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/* ILO (input) INTEGER */
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/* IHI (input) INTEGER */
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/* It is assumed that H is already upper triangular */
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/* in rows and columns 1:ILO-1 and IHI+1:N. */
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/* LWORK (input) integer scalar */
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/* The amount of workspace available. */
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/* Further Details */
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/* =============== */
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/* Little is known about how best to choose these parameters. */
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/* It is possible to use different values of the parameters */
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/* for each of CHSEQR, DHSEQR, SHSEQR and ZHSEQR. */
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/* It is probably best to choose different parameters for */
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/* different matrices and different parameters at different */
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/* times during the iteration, but this has not been */
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/* implemented --- yet. */
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/* The best choices of most of the parameters depend */
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/* in an ill-understood way on the relative execution */
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/* rate of xLAQR3 and xLAQR5 and on the nature of each */
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/* particular eigenvalue problem. Experiment may be the */
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/* only practical way to determine which choices are most */
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/* effective. */
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/* Following is a list of default values supplied by IPARMQ. */
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/* These defaults may be adjusted in order to attain better */
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/* performance in any particular computational environment. */
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/* IPARMQ(ISPEC=12) The xLAHQR vs xLAQR0 crossover point. */
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/* Default: 75. (Must be at least 11.) */
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/* IPARMQ(ISPEC=13) Recommended deflation window size. */
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/* This depends on ILO, IHI and NS, the */
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/* number of simultaneous shifts returned */
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/* by IPARMQ(ISPEC=15). The default for */
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/* (IHI-ILO+1).LE.500 is NS. The default */
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/* for (IHI-ILO+1).GT.500 is 3*NS/2. */
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/* IPARMQ(ISPEC=14) Nibble crossover point. Default: 14. */
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/* IPARMQ(ISPEC=15) Number of simultaneous shifts, NS. */
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/* a multi-shift QR iteration. */
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/* If IHI-ILO+1 is ... */
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/* greater than ...but less ... the */
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/* or equal to ... than default is */
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/* 0 30 NS = 2+ */
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/* 30 60 NS = 4+ */
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/* 60 150 NS = 10 */
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/* 150 590 NS = ** */
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/* 590 3000 NS = 64 */
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/* 3000 6000 NS = 128 */
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/* 6000 infinity NS = 256 */
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/* (+) By default matrices of this order are */
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/* passed to the implicit double shift routine */
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/* xLAHQR. See IPARMQ(ISPEC=12) above. These */
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/* values of NS are used only in case of a rare */
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/* xLAHQR failure. */
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/* (**) The asterisks (**) indicate an ad-hoc */
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/* function increasing from 10 to 64. */
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/* IPARMQ(ISPEC=16) Select structured matrix multiply. */
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/* (See ISPEC=16 above for details.) */
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/* Default: 3. */
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/* ================================================================ */
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/* .. Parameters .. */
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/* .. */
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/* .. Local Scalars .. */
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/* .. */
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/* .. Intrinsic Functions .. */
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/* .. */
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/* .. Executable Statements .. */
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if (*ispec == 15 || *ispec == 13 || *ispec == 16) {
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/* ==== Set the number simultaneous shifts ==== */
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nh = *ihi - *ilo + 1;
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ns = 2;
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if (nh >= 30) {
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ns = 4;
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}
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if (nh >= 60) {
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ns = 10;
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}
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if (nh >= 150) {
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/* Computing MAX */
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r__1 = log((real) nh) / log(2.f);
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i__1 = 10, i__2 = nh / i_nint(&r__1);
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ns = max(i__1,i__2);
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}
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if (nh >= 590) {
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ns = 64;
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}
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if (nh >= 3000) {
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ns = 128;
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}
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if (nh >= 6000) {
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ns = 256;
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}
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/* Computing MAX */
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i__1 = 2, i__2 = ns - ns % 2;
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ns = max(i__1,i__2);
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}
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if (*ispec == 12) {
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/* ===== Matrices of order smaller than NMIN get sent */
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/* . to xLAHQR, the classic double shift algorithm. */
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/* . This must be at least 11. ==== */
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ret_val = 75;
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} else if (*ispec == 14) {
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/* ==== INIBL: skip a multi-shift qr iteration and */
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/* . whenever aggressive early deflation finds */
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/* . at least (NIBBLE*(window size)/100) deflations. ==== */
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ret_val = 14;
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} else if (*ispec == 15) {
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/* ==== NSHFTS: The number of simultaneous shifts ===== */
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ret_val = ns;
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} else if (*ispec == 13) {
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/* ==== NW: deflation window size. ==== */
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if (nh <= 500) {
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ret_val = ns;
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} else {
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ret_val = ns * 3 / 2;
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}
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} else if (*ispec == 16) {
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/* ==== IACC22: Whether to accumulate reflections */
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/* . before updating the far-from-diagonal elements */
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/* . and whether to use 2-by-2 block structure while */
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/* . doing it. A small amount of work could be saved */
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/* . by making this choice dependent also upon the */
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/* . NH=IHI-ILO+1. */
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ret_val = 0;
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if (ns >= 14) {
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ret_val = 1;
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}
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if (ns >= 14) {
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ret_val = 2;
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}
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} else {
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/* ===== invalid value of ispec ===== */
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ret_val = -1;
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}
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/* ==== End of IPARMQ ==== */
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return ret_val;
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} /* iparmq_ */
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