112 lines
3.5 KiB
Fortran
112 lines
3.5 KiB
Fortran
*> \brief \b XLAENV
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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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* SUBROUTINE XLAENV( ISPEC, NVALUE )
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*
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* .. Scalar Arguments ..
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* INTEGER ISPEC, NVALUE
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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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*> XLAENV sets certain machine- and problem-dependent quantities
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*> which will later be retrieved by ILAENV.
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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 set in the COMMON array IPARMS.
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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: another crossover point, for the multishift QR and QZ
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*> methods 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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*> (used by xGELSD and xGESDD)
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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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*> 12 <= ISPEC <= 16:
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*> xHSEQR or one of its subroutines,
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*> see IPARMQ for detailed explanation
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*> \endverbatim
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*>
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*> \param[in] NVALUE
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*> \verbatim
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*> NVALUE is INTEGER
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*> The value of the parameter specified by ISPEC.
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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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*> \ingroup aux_eig
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*
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* =====================================================================
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SUBROUTINE XLAENV( ISPEC, NVALUE )
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*
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* -- LAPACK test routine --
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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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*
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* .. Scalar Arguments ..
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INTEGER ISPEC, NVALUE
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* ..
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*
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* =====================================================================
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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.16 ) THEN
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IPARMS( ISPEC ) = NVALUE
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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 XLAENV
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*
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END
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