233 lines
6.8 KiB
Fortran
233 lines
6.8 KiB
Fortran
*> \brief \b ILAENV
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*
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* =========== DOCUMENTATION ===========
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*
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* Online html documentation available at
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* http://www.netlib.org/lapack/explore-html/
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*
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* Definition:
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* ===========
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*
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* INTEGER FUNCTION ILAENV( ISPEC, NAME, OPTS, N1, N2, N3,
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* N4 )
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*
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* .. Scalar Arguments ..
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* CHARACTER*( * ) NAME, OPTS
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* INTEGER ISPEC, N1, N2, N3, N4
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* ..
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*
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*
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*> \par Purpose:
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* =============
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*>
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*> \verbatim
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*>
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*> ILAENV returns problem-dependent parameters for the local
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*> environment. See ISPEC for a description of the parameters.
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*>
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*> In this version, the problem-dependent parameters are contained in
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*> the integer array IPARMS in the common block CLAENV and the value
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*> with index ISPEC is copied to ILAENV. This version of ILAENV is
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*> to be used in conjunction with XLAENV in TESTING and TIMING.
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*> \endverbatim
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*
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* Arguments:
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* ==========
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*
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*> \param[in] ISPEC
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*> \verbatim
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*> ISPEC is INTEGER
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*> Specifies the parameter to be returned as the value of
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*> ILAENV.
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*> = 1: the optimal blocksize; if this value is 1, an unblocked
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*> algorithm will give the best performance.
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*> = 2: the minimum block size for which the block routine
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*> should be used; if the usable block size is less than
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*> this value, an unblocked routine should be used.
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*> = 3: the crossover point (in a block routine, for N less
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*> than this value, an unblocked routine should be used)
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*> = 4: the number of shifts, used in the nonsymmetric
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*> eigenvalue routines
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*> = 5: the minimum column dimension for blocking to be used;
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*> rectangular blocks must have dimension at least k by m,
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*> where k is given by ILAENV(2,...) and m by ILAENV(5,...)
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*> = 6: the crossover point for the SVD (when reducing an m by n
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*> matrix to bidiagonal form, if max(m,n)/min(m,n) exceeds
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*> this value, a QR factorization is used first to reduce
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*> the matrix to a triangular form.)
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*> = 7: the number of processors
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*> = 8: the crossover point for the multishift QR and QZ methods
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*> for nonsymmetric eigenvalue problems.
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*> = 9: maximum size of the subproblems at the bottom of the
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*> computation tree in the divide-and-conquer algorithm
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*> =10: ieee NaN arithmetic can be trusted not to trap
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*> =11: infinity arithmetic can be trusted not to trap
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*>
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*> Other specifications (up to 100) can be added later.
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*> \endverbatim
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*>
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*> \param[in] NAME
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*> \verbatim
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*> NAME is CHARACTER*(*)
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*> The name of the calling subroutine.
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*> \endverbatim
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*>
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*> \param[in] OPTS
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*> \verbatim
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*> OPTS is CHARACTER*(*)
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*> The character options to the subroutine NAME, concatenated
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*> into a single character string. For example, UPLO = 'U',
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*> TRANS = 'T', and DIAG = 'N' for a triangular routine would
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*> be specified as OPTS = 'UTN'.
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*> \endverbatim
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*>
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*> \param[in] N1
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*> \verbatim
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*> N1 is INTEGER
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*> \endverbatim
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*>
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*> \param[in] N2
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*> \verbatim
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*> N2 is INTEGER
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*> \endverbatim
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*>
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*> \param[in] N3
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*> \verbatim
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*> N3 is INTEGER
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*> \endverbatim
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*>
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*> \param[in] N4
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*> \verbatim
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*> N4 is INTEGER
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*>
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*> Problem dimensions for the subroutine NAME; these may not all
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*> be required.
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*> \endverbatim
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*>
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*> \return ILAENV
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*> \verbatim
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*> ILAENV is INTEGER
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*> >= 0: the value of the parameter specified by ISPEC
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*> < 0: if ILAENV = -k, the k-th argument had an illegal value.
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*> \endverbatim
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*
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* Authors:
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* ========
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*
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*> \author Univ. of Tennessee
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*> \author Univ. of California Berkeley
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*> \author Univ. of Colorado Denver
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*> \author NAG Ltd.
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*
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*> \date November 2011
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*
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*> \ingroup aux_lin
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*
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*> \par Further Details:
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* =====================
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*>
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*> \verbatim
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*>
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*> The following conventions have been used when calling ILAENV from the
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*> LAPACK routines:
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*> 1) OPTS is a concatenation of all of the character options to
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*> subroutine NAME, in the same order that they appear in the
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*> argument list for NAME, even if they are not used in determining
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*> the value of the parameter specified by ISPEC.
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*> 2) The problem dimensions N1, N2, N3, N4 are specified in the order
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*> that they appear in the argument list for NAME. N1 is used
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*> first, N2 second, and so on, and unused problem dimensions are
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*> passed a value of -1.
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*> 3) The parameter value returned by ILAENV is checked for validity in
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*> the calling subroutine. For example, ILAENV is used to retrieve
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*> the optimal blocksize for STRTRI as follows:
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*>
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*> NB = ILAENV( 1, 'STRTRI', UPLO // DIAG, N, -1, -1, -1 )
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*> IF( NB.LE.1 ) NB = MAX( 1, N )
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*> \endverbatim
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*>
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* =====================================================================
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INTEGER FUNCTION ILAENV( ISPEC, NAME, OPTS, N1, N2, N3,
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$ N4 )
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*
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* -- LAPACK test routine (version 3.4.0) --
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* -- LAPACK is a software package provided by Univ. of Tennessee, --
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* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
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* November 2011
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*
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* .. Scalar Arguments ..
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CHARACTER*( * ) NAME, OPTS
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INTEGER ISPEC, N1, N2, N3, N4
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* ..
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*
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* =====================================================================
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*
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* .. Intrinsic Functions ..
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INTRINSIC INT, MIN, REAL
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* ..
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* .. External Functions ..
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INTEGER IEEECK
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EXTERNAL IEEECK
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* ..
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* .. Arrays in Common ..
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INTEGER IPARMS( 100 )
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* ..
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* .. Common blocks ..
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COMMON / CLAENV / IPARMS
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* ..
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* .. Save statement ..
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SAVE / CLAENV /
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* ..
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* .. Executable Statements ..
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*
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IF( ISPEC.GE.1 .AND. ISPEC.LE.5 ) THEN
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*
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* Return a value from the common block.
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*
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ILAENV = IPARMS( ISPEC )
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*
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ELSE IF( ISPEC.EQ.6 ) THEN
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*
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* Compute SVD crossover point.
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*
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ILAENV = INT( REAL( MIN( N1, N2 ) )*1.6E0 )
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*
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ELSE IF( ISPEC.GE.7 .AND. ISPEC.LE.9 ) THEN
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*
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* Return a value from the common block.
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*
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ILAENV = IPARMS( ISPEC )
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*
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ELSE IF( ISPEC.EQ.10 ) THEN
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*
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* IEEE NaN arithmetic can be trusted not to trap
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*
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C ILAENV = 0
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ILAENV = 1
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IF( ILAENV.EQ.1 ) THEN
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ILAENV = IEEECK( 1, 0.0, 1.0 )
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END IF
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*
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ELSE IF( ISPEC.EQ.11 ) THEN
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*
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* Infinity arithmetic can be trusted not to trap
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*
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C ILAENV = 0
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ILAENV = 1
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IF( ILAENV.EQ.1 ) THEN
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ILAENV = IEEECK( 0, 0.0, 1.0 )
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END IF
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*
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ELSE
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*
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* Invalid value for ISPEC
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*
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ILAENV = -1
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END IF
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*
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RETURN
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*
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* End of ILAENV
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*
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END
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