From db464f35f5a10b58d9ed1085e0b462689adee583 Mon Sep 17 00:00:00 2001 From: Siddhesh Wani Date: Mon, 25 May 2015 14:46:31 +0530 Subject: Original Version --- src/fortran/lapack/iparmq.f | 253 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 253 insertions(+) create mode 100644 src/fortran/lapack/iparmq.f (limited to 'src/fortran/lapack/iparmq.f') diff --git a/src/fortran/lapack/iparmq.f b/src/fortran/lapack/iparmq.f new file mode 100644 index 00000000..d9d0af36 --- /dev/null +++ b/src/fortran/lapack/iparmq.f @@ -0,0 +1,253 @@ + INTEGER FUNCTION IPARMQ( ISPEC, NAME, OPTS, N, ILO, IHI, LWORK ) +* +* -- LAPACK auxiliary routine (version 3.1) -- +* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. +* November 2006 +* +* .. Scalar Arguments .. + INTEGER IHI, ILO, ISPEC, LWORK, N + CHARACTER NAME*( * ), OPTS*( * ) +* +* 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 .. + INTEGER INMIN, INWIN, INIBL, ISHFTS, IACC22 + PARAMETER ( INMIN = 12, INWIN = 13, INIBL = 14, + $ ISHFTS = 15, IACC22 = 16 ) + INTEGER NMIN, K22MIN, KACMIN, NIBBLE, KNWSWP + PARAMETER ( NMIN = 75, K22MIN = 14, KACMIN = 14, + $ NIBBLE = 14, KNWSWP = 500 ) + REAL TWO + PARAMETER ( TWO = 2.0 ) +* .. +* .. Local Scalars .. + INTEGER NH, NS +* .. +* .. Intrinsic Functions .. + INTRINSIC LOG, MAX, MOD, NINT, REAL +* .. +* .. Executable Statements .. + IF( ( ISPEC.EQ.ISHFTS ) .OR. ( ISPEC.EQ.INWIN ) .OR. + $ ( ISPEC.EQ.IACC22 ) ) THEN +* +* ==== Set the number simultaneous shifts ==== +* + NH = IHI - ILO + 1 + NS = 2 + IF( NH.GE.30 ) + $ NS = 4 + IF( NH.GE.60 ) + $ NS = 10 + IF( NH.GE.150 ) + $ NS = MAX( 10, NH / NINT( LOG( REAL( NH ) ) / LOG( TWO ) ) ) + IF( NH.GE.590 ) + $ NS = 64 + IF( NH.GE.3000 ) + $ NS = 128 + IF( NH.GE.6000 ) + $ NS = 256 + NS = MAX( 2, NS-MOD( NS, 2 ) ) + END IF +* + IF( ISPEC.EQ.INMIN ) THEN +* +* +* ===== Matrices of order smaller than NMIN get sent +* . to xLAHQR, the classic double shift algorithm. +* . This must be at least 11. ==== +* + IPARMQ = NMIN +* + ELSE IF( ISPEC.EQ.INIBL ) THEN +* +* ==== INIBL: skip a multi-shift qr iteration and +* . whenever aggressive early deflation finds +* . at least (NIBBLE*(window size)/100) deflations. ==== +* + IPARMQ = NIBBLE +* + ELSE IF( ISPEC.EQ.ISHFTS ) THEN +* +* ==== NSHFTS: The number of simultaneous shifts ===== +* + IPARMQ = NS +* + ELSE IF( ISPEC.EQ.INWIN ) THEN +* +* ==== NW: deflation window size. ==== +* + IF( NH.LE.KNWSWP ) THEN + IPARMQ = NS + ELSE + IPARMQ = 3*NS / 2 + END IF +* + ELSE IF( ISPEC.EQ.IACC22 ) THEN +* +* ==== 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. +* + IPARMQ = 0 + IF( NS.GE.KACMIN ) + $ IPARMQ = 1 + IF( NS.GE.K22MIN ) + $ IPARMQ = 2 +* + ELSE +* ===== invalid value of ispec ===== + IPARMQ = -1 +* + END IF +* +* ==== End of IPARMQ ==== +* + END -- cgit