--- /dev/null
+#include "clapack.h"
+
+integer iparmq_(integer *ispec, char *name__, char *opts, integer *n, integer
+ *ilo, integer *ihi, integer *lwork)
+{
+ /* System generated locals */
+ integer ret_val, i__1, i__2;
+ real r__1;
+
+ /* Builtin functions */
+ double log(doublereal);
+ integer i_nint(real *);
+
+ /* Local variables */
+ integer nh, ns;
+
+
+/* -- LAPACK auxiliary routine (version 3.1) -- */
+/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
+/* November 2006 */
+
+/* .. Scalar Arguments .. */
+
+/* Purpose */
+/* ======= */
+
+/* This program sets problem and machine dependent parameters */
+/* useful for xHSEQR and its subroutines. It is called whenever */
+/* ILAENV is called with 12 <= ISPEC <= 16 */
+
+/* Arguments */
+/* ========= */
+
+/* ISPEC (input) integer scalar */
+/* ISPEC specifies which tunable parameter IPARMQ should */
+/* return. */
+
+/* ISPEC=12: (INMIN) Matrices of order nmin or less */
+/* are sent directly to xLAHQR, the implicit */
+/* double shift QR algorithm. NMIN must be */
+/* at least 11. */
+
+/* ISPEC=13: (INWIN) Size of the deflation window. */
+/* This is best set greater than or equal to */
+/* the number of simultaneous shifts NS. */
+/* Larger matrices benefit from larger deflation */
+/* windows. */
+
+/* ISPEC=14: (INIBL) Determines when to stop nibbling and */
+/* invest in an (expensive) multi-shift QR sweep. */
+/* If the aggressive early deflation subroutine */
+/* finds LD converged eigenvalues from an order */
+/* NW deflation window and LD.GT.(NW*NIBBLE)/100, */
+/* then the next QR sweep is skipped and early */
+/* deflation is applied immediately to the */
+/* remaining active diagonal block. Setting */
+/* IPARMQ(ISPEC=14) = 0 causes TTQRE to skip a */
+/* multi-shift QR sweep whenever early deflation */
+/* finds a converged eigenvalue. Setting */
+/* IPARMQ(ISPEC=14) greater than or equal to 100 */
+/* prevents TTQRE from skipping a multi-shift */
+/* QR sweep. */
+
+/* ISPEC=15: (NSHFTS) The number of simultaneous shifts in */
+/* a multi-shift QR iteration. */
+
+/* ISPEC=16: (IACC22) IPARMQ is set to 0, 1 or 2 with the */
+/* following meanings. */
+/* 0: During the multi-shift QR sweep, */
+/* xLAQR5 does not accumulate reflections and */
+/* does not use matrix-matrix multiply to */
+/* update the far-from-diagonal matrix */
+/* entries. */
+/* 1: During the multi-shift QR sweep, */
+/* xLAQR5 and/or xLAQRaccumulates reflections and uses */
+/* matrix-matrix multiply to update the */
+/* far-from-diagonal matrix entries. */
+/* 2: During the multi-shift QR sweep. */
+/* xLAQR5 accumulates reflections and takes */
+/* advantage of 2-by-2 block structure during */
+/* matrix-matrix multiplies. */
+/* (If xTRMM is slower than xGEMM, then */
+/* IPARMQ(ISPEC=16)=1 may be more efficient than */
+/* IPARMQ(ISPEC=16)=2 despite the greater level of */
+/* arithmetic work implied by the latter choice.) */
+
+/* NAME (input) character string */
+/* Name of the calling subroutine */
+
+/* OPTS (input) character string */
+/* This is a concatenation of the string arguments to */
+/* TTQRE. */
+
+/* N (input) integer scalar */
+/* N is the order of the Hessenberg matrix H. */
+
+/* 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. */
+
+/* LWORK (input) integer scalar */
+/* The amount of workspace available. */
+
+/* Further Details */
+/* =============== */
+
+/* Little is known about how best to choose these parameters. */
+/* It is possible to use different values of the parameters */
+/* for each of CHSEQR, DHSEQR, SHSEQR and ZHSEQR. */
+
+/* It is probably best to choose different parameters for */
+/* different matrices and different parameters at different */
+/* times during the iteration, but this has not been */
+/* implemented --- yet. */
+
+
+/* The best choices of most of the parameters depend */
+/* in an ill-understood way on the relative execution */
+/* rate of xLAQR3 and xLAQR5 and on the nature of each */
+/* particular eigenvalue problem. Experiment may be the */
+/* only practical way to determine which choices are most */
+/* effective. */
+
+/* Following is a list of default values supplied by IPARMQ. */
+/* These defaults may be adjusted in order to attain better */
+/* performance in any particular computational environment. */
+
+/* IPARMQ(ISPEC=12) The xLAHQR vs xLAQR0 crossover point. */
+/* Default: 75. (Must be at least 11.) */
+
+/* IPARMQ(ISPEC=13) Recommended deflation window size. */
+/* This depends on ILO, IHI and NS, the */
+/* number of simultaneous shifts returned */
+/* by IPARMQ(ISPEC=15). The default for */
+/* (IHI-ILO+1).LE.500 is NS. The default */
+/* for (IHI-ILO+1).GT.500 is 3*NS/2. */
+
+/* IPARMQ(ISPEC=14) Nibble crossover point. Default: 14. */
+
+/* IPARMQ(ISPEC=15) Number of simultaneous shifts, NS. */
+/* a multi-shift QR iteration. */
+
+/* If IHI-ILO+1 is ... */
+
+/* greater than ...but less ... the */
+/* or equal to ... than default is */
+
+/* 0 30 NS = 2+ */
+/* 30 60 NS = 4+ */
+/* 60 150 NS = 10 */
+/* 150 590 NS = ** */
+/* 590 3000 NS = 64 */
+/* 3000 6000 NS = 128 */
+/* 6000 infinity NS = 256 */
+
+/* (+) By default matrices of this order are */
+/* passed to the implicit double shift routine */
+/* xLAHQR. See IPARMQ(ISPEC=12) above. These */
+/* values of NS are used only in case of a rare */
+/* xLAHQR failure. */
+
+/* (**) The asterisks (**) indicate an ad-hoc */
+/* function increasing from 10 to 64. */
+
+/* IPARMQ(ISPEC=16) Select structured matrix multiply. */
+/* (See ISPEC=16 above for details.) */
+/* Default: 3. */
+
+/* ================================================================ */
+/* .. Parameters .. */
+/* .. */
+/* .. Local Scalars .. */
+/* .. */
+/* .. Intrinsic Functions .. */
+/* .. */
+/* .. Executable Statements .. */
+ if (*ispec == 15 || *ispec == 13 || *ispec == 16) {
+
+/* ==== Set the number simultaneous shifts ==== */
+
+ nh = *ihi - *ilo + 1;
+ ns = 2;
+ if (nh >= 30) {
+ ns = 4;
+ }
+ if (nh >= 60) {
+ ns = 10;
+ }
+ if (nh >= 150) {
+/* Computing MAX */
+ r__1 = (real)(log((doublereal) nh) / log(2.));
+ i__1 = 10, i__2 = nh / i_nint(&r__1);
+ ns = max(i__1,i__2);
+ }
+ if (nh >= 590) {
+ ns = 64;
+ }
+ if (nh >= 3000) {
+ ns = 128;
+ }
+ if (nh >= 6000) {
+ ns = 256;
+ }
+/* Computing MAX */
+ i__1 = 2, i__2 = ns - ns % 2;
+ ns = max(i__1,i__2);
+ }
+
+ if (*ispec == 12) {
+
+
+/* ===== Matrices of order smaller than NMIN get sent */
+/* . to xLAHQR, the classic double shift algorithm. */
+/* . This must be at least 11. ==== */
+
+ ret_val = 75;
+
+ } else if (*ispec == 14) {
+
+/* ==== INIBL: skip a multi-shift qr iteration and */
+/* . whenever aggressive early deflation finds */
+/* . at least (NIBBLE*(window size)/100) deflations. ==== */
+
+ ret_val = 14;
+
+ } else if (*ispec == 15) {
+
+/* ==== NSHFTS: The number of simultaneous shifts ===== */
+
+ ret_val = ns;
+
+ } else if (*ispec == 13) {
+
+/* ==== NW: deflation window size. ==== */
+
+ if (nh <= 500) {
+ ret_val = ns;
+ } else {
+ ret_val = ns * 3 / 2;
+ }
+
+ } else if (*ispec == 16) {
+
+/* ==== IACC22: Whether to accumulate reflections */
+/* . before updating the far-from-diagonal elements */
+/* . and whether to use 2-by-2 block structure while */
+/* . doing it. A small amount of work could be saved */
+/* . by making this choice dependent also upon the */
+/* . NH=IHI-ILO+1. */
+
+ ret_val = 0;
+ if (ns >= 14) {
+ ret_val = 1;
+ }
+ if (ns >= 14) {
+ ret_val = 2;
+ }
+
+ } else {
+/* ===== invalid value of ispec ===== */
+ ret_val = -1;
+
+ }
+
+/* ==== End of IPARMQ ==== */
+
+ return ret_val;
+} /* iparmq_ */
projects / opencv / blobdiff