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|
*> \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
*>
*> 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
*>
*> \return 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.
*
*> \date November 2011
*
*> \ingroup aux_lin
*
*> \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 (version 3.4.0) --
* -- LAPACK is a software package provided by Univ. of Tennessee, --
* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
* November 2011
*
* .. Scalar Arguments ..
CHARACTER*( * ) NAME, OPTS
INTEGER ISPEC, N1, N2, N3, N4
* ..
*
* =====================================================================
*
* .. Intrinsic Functions ..
INTRINSIC INT, MIN, REAL
* ..
* .. External Functions ..
INTEGER IEEECK
EXTERNAL IEEECK
* ..
* .. 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
*
* Invalid value for ISPEC
*
ILAENV = -1
END IF
*
RETURN
*
* End of ILAENV
*
END
|
