*> \brief \b ILAENV * * =========== DOCUMENTATION =========== * * Online html documentation available at * http://www.netlib.org/lapack/explore-html/ * * Definition: * =========== * * INTEGER FUNCTION ILAENV( ISPEC, NAME, OPTS, N1, N2, N3, * N4 ) * * .. Scalar Arguments .. * CHARACTER*( * ) NAME, OPTS * INTEGER ISPEC, N1, N2, N3, N4 * .. * * *> \par Purpose: * ============= *> *> \verbatim *> *> ILAENV returns problem-dependent parameters for the local *> environment. See ISPEC for a description of the parameters. *> *> In this version, the problem-dependent parameters are contained in *> the integer array IPARMS in the common block CLAENV and the value *> with index ISPEC is copied to ILAENV. This version of ILAENV is *> to be used in conjunction with XLAENV in TESTING and TIMING. *> \endverbatim * * Arguments: * ========== * *> \param[in] ISPEC *> \verbatim *> ISPEC is INTEGER *> Specifies the parameter to be returned as the value of *> ILAENV. *> = 1: the optimal blocksize; if this value is 1, an unblocked *> algorithm will give the best performance. *> = 2: the minimum block size for which the block routine *> should be used; if the usable block size is less than *> this value, an unblocked routine should be used. *> = 3: the crossover point (in a block routine, for N less *> than this value, an unblocked routine should be used) *> = 4: the number of shifts, used in the nonsymmetric *> eigenvalue routines *> = 5: the minimum column dimension for blocking to be used; *> rectangular blocks must have dimension at least k by m, *> where k is given by ILAENV(2,...) and m by ILAENV(5,...) *> = 6: the crossover point for the SVD (when reducing an m by n *> matrix to bidiagonal form, if max(m,n)/min(m,n) exceeds *> this value, a QR factorization is used first to reduce *> the matrix to a triangular form.) *> = 7: the number of processors *> = 8: the crossover point for the multishift QR and QZ methods *> for nonsymmetric eigenvalue problems. *> = 9: maximum size of the subproblems at the bottom of the *> computation tree in the divide-and-conquer algorithm *> =10: ieee NaN arithmetic can be trusted not to trap *> =11: infinity arithmetic can be trusted not to trap *> 12 <= ISPEC <= 16: *> xHSEQR or one of its subroutines, *> see IPARMQ for detailed explanation *> *> Other specifications (up to 100) can be added later. *> \endverbatim *> *> \param[in] NAME *> \verbatim *> NAME is CHARACTER*(*) *> The name of the calling subroutine. *> \endverbatim *> *> \param[in] OPTS *> \verbatim *> OPTS is CHARACTER*(*) *> The character options to the subroutine NAME, concatenated *> into a single character string. For example, UPLO = 'U', *> TRANS = 'T', and DIAG = 'N' for a triangular routine would *> be specified as OPTS = 'UTN'. *> \endverbatim *> *> \param[in] N1 *> \verbatim *> N1 is INTEGER *> \endverbatim *> *> \param[in] N2 *> \verbatim *> N2 is INTEGER *> \endverbatim *> *> \param[in] N3 *> \verbatim *> N3 is INTEGER *> \endverbatim *> *> \param[in] N4 *> \verbatim *> N4 is INTEGER *> *> Problem dimensions for the subroutine NAME; these may not all *> be required. *> \endverbatim *> *> \result ILAENV *> \verbatim *> ILAENV is INTEGER *> >= 0: the value of the parameter specified by ISPEC *> < 0: if ILAENV = -k, the k-th argument had an illegal value. *> \endverbatim * * Authors: * ======== * *> \author Univ. of Tennessee *> \author Univ. of California Berkeley *> \author Univ. of Colorado Denver *> \author NAG Ltd. * *> \ingroup OTHERauxiliary * *> \par Further Details: * ===================== *> *> \verbatim *> *> The following conventions have been used when calling ILAENV from the *> LAPACK routines: *> 1) OPTS is a concatenation of all of the character options to *> subroutine NAME, in the same order that they appear in the *> argument list for NAME, even if they are not used in determining *> the value of the parameter specified by ISPEC. *> 2) The problem dimensions N1, N2, N3, N4 are specified in the order *> that they appear in the argument list for NAME. N1 is used *> first, N2 second, and so on, and unused problem dimensions are *> passed a value of -1. *> 3) The parameter value returned by ILAENV is checked for validity in *> the calling subroutine. For example, ILAENV is used to retrieve *> the optimal blocksize for STRTRI as follows: *> *> NB = ILAENV( 1, 'STRTRI', UPLO // DIAG, N, -1, -1, -1 ) *> IF( NB.LE.1 ) NB = MAX( 1, N ) *> \endverbatim *> * ===================================================================== INTEGER FUNCTION ILAENV( ISPEC, NAME, OPTS, N1, N2, N3, $ N4 ) * * -- LAPACK test routine -- * -- LAPACK is a software package provided by Univ. of Tennessee, -- * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- * * .. Scalar Arguments .. CHARACTER*( * ) NAME, OPTS INTEGER ISPEC, N1, N2, N3, N4 * .. * * ===================================================================== * * .. Intrinsic Functions .. INTRINSIC INT, MIN, REAL * .. * .. External Functions .. INTEGER IEEECK, IPARAM2STAGE EXTERNAL IEEECK, IPARAM2STAGE * .. * .. Arrays in Common .. INTEGER IPARMS( 100 ) * .. * .. Common blocks .. COMMON / CLAENV / IPARMS * .. * .. Save statement .. SAVE / CLAENV / * .. * .. Executable Statements .. * IF( ISPEC.GE.1 .AND. ISPEC.LE.5 ) THEN * * Return a value from the common block. * ILAENV = IPARMS( ISPEC ) * ELSE IF( ISPEC.EQ.6 ) THEN * * Compute SVD crossover point. * ILAENV = INT( REAL( MIN( N1, N2 ) )*1.6E0 ) * ELSE IF( ISPEC.GE.7 .AND. ISPEC.LE.9 ) THEN * * Return a value from the common block. * ILAENV = IPARMS( ISPEC ) * ELSE IF( ISPEC.EQ.10 ) THEN * * IEEE NaN arithmetic can be trusted not to trap * C ILAENV = 0 ILAENV = 1 IF( ILAENV.EQ.1 ) THEN ILAENV = IEEECK( 1, 0.0, 1.0 ) END IF * ELSE IF( ISPEC.EQ.11 ) THEN * * Infinity arithmetic can be trusted not to trap * C ILAENV = 0 ILAENV = 1 IF( ILAENV.EQ.1 ) THEN ILAENV = IEEECK( 0, 0.0, 1.0 ) END IF * ELSE IF(( ISPEC.GE.12 ) .AND. (ISPEC.LE.16)) THEN * * 12 <= ISPEC <= 16: xHSEQR or one of its subroutines. * ILAENV = IPARMS( ISPEC ) * WRITE(*,*) 'ISPEC = ',ISPEC,' ILAENV =',ILAENV * ILAENV = IPARMQ( ISPEC, NAME, OPTS, N1, N2, N3, N4 ) * ELSE IF(( ISPEC.GE.17 ) .AND. (ISPEC.LE.21)) THEN * * 17 <= ISPEC <= 21: 2stage eigenvalues SVD routines. * IF( ISPEC.EQ.17 ) THEN ILAENV = IPARMS( 1 ) ELSE ILAENV = IPARAM2STAGE( ISPEC, NAME, OPTS, N1, N2, N3, N4 ) ENDIF * ELSE * * Invalid value for ISPEC * ILAENV = -1 END IF * RETURN * * End of ILAENV * END INTEGER FUNCTION ILAENV2STAGE( ISPEC, NAME, OPTS, N1, N2, $ N3, N4 ) * .. Scalar Arguments .. CHARACTER*( * ) NAME, OPTS INTEGER ISPEC, N1, N2, N3, N4 * .. * * ===================================================================== * * .. Local variables .. INTEGER IISPEC * .. External Functions .. INTEGER IPARAM2STAGE EXTERNAL IPARAM2STAGE * .. * .. Arrays in Common .. INTEGER IPARMS( 100 ) * .. * .. Common blocks .. COMMON / CLAENV / IPARMS * .. * .. Save statement .. SAVE / CLAENV / * .. * .. Executable Statements .. * IF(( ISPEC.GE.1 ) .AND. (ISPEC.LE.5)) THEN * * 1 <= ISPEC <= 5: 2stage eigenvalues SVD routines. * IF( ISPEC.EQ.1 ) THEN ILAENV2STAGE = IPARMS( 1 ) ELSE IISPEC = 16 + ISPEC ILAENV2STAGE = IPARAM2STAGE( IISPEC, NAME, OPTS, $ N1, N2, N3, N4 ) ENDIF * ELSE * * Invalid value for ISPEC * ILAENV2STAGE = -1 END IF * RETURN * * End of ILAENV2STAGE * END INTEGER FUNCTION IPARMQ( ISPEC, NAME, OPTS, N, ILO, IHI, LWORK ) * 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 = 11, K22MIN = 14, KACMIN = 14, $ NIBBLE = 14, KNWSWP = 500 ) REAL TWO PARAMETER ( TWO = 2.0 ) * .. * .. Scalar Arguments .. INTEGER IHI, ILO, ISPEC, LWORK, N CHARACTER NAME*( * ), OPTS*( * ) * .. * .. 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 LAHQR, 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