LAPACK  3.4.1
LAPACK: Linear Algebra PACKage
xlaenv.f
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00001 *> \brief \b XLAENV
00002 *
00003 *  =========== DOCUMENTATION ===========
00004 *
00005 * Online html documentation available at 
00006 *            http://www.netlib.org/lapack/explore-html/ 
00007 *
00008 *  Definition:
00009 *  ===========
00010 *
00011 *       SUBROUTINE XLAENV( ISPEC, NVALUE )
00012 * 
00013 *       .. Scalar Arguments ..
00014 *       INTEGER            ISPEC, NVALUE
00015 *       ..
00016 *  
00017 *
00018 *> \par Purpose:
00019 *  =============
00020 *>
00021 *> \verbatim
00022 *>
00023 *> XLAENV sets certain machine- and problem-dependent quantities
00024 *> which will later be retrieved by ILAENV.
00025 *> \endverbatim
00026 *
00027 *  Arguments:
00028 *  ==========
00029 *
00030 *> \param[in] ISPEC
00031 *> \verbatim
00032 *>          ISPEC is INTEGER
00033 *>          Specifies the parameter to be set in the COMMON array IPARMS.
00034 *>          = 1: the optimal blocksize; if this value is 1, an unblocked
00035 *>               algorithm will give the best performance.
00036 *>          = 2: the minimum block size for which the block routine
00037 *>               should be used; if the usable block size is less than
00038 *>               this value, an unblocked routine should be used.
00039 *>          = 3: the crossover point (in a block routine, for N less
00040 *>               than this value, an unblocked routine should be used)
00041 *>          = 4: the number of shifts, used in the nonsymmetric
00042 *>               eigenvalue routines
00043 *>          = 5: the minimum column dimension for blocking to be used;
00044 *>               rectangular blocks must have dimension at least k by m,
00045 *>               where k is given by ILAENV(2,...) and m by ILAENV(5,...)
00046 *>          = 6: the crossover point for the SVD (when reducing an m by n
00047 *>               matrix to bidiagonal form, if max(m,n)/min(m,n) exceeds
00048 *>               this value, a QR factorization is used first to reduce
00049 *>               the matrix to a triangular form)
00050 *>          = 7: the number of processors
00051 *>          = 8: another crossover point, for the multishift QR and QZ
00052 *>               methods for nonsymmetric eigenvalue problems.
00053 *>          = 9: maximum size of the subproblems at the bottom of the
00054 *>               computation tree in the divide-and-conquer algorithm
00055 *>               (used by xGELSD and xGESDD)
00056 *>          =10: ieee NaN arithmetic can be trusted not to trap
00057 *>          =11: infinity arithmetic can be trusted not to trap
00058 *> \endverbatim
00059 *>
00060 *> \param[in] NVALUE
00061 *> \verbatim
00062 *>          NVALUE is INTEGER
00063 *>          The value of the parameter specified by ISPEC.
00064 *> \endverbatim
00065 *
00066 *  Authors:
00067 *  ========
00068 *
00069 *> \author Univ. of Tennessee 
00070 *> \author Univ. of California Berkeley 
00071 *> \author Univ. of Colorado Denver 
00072 *> \author NAG Ltd. 
00073 *
00074 *> \date November 2011
00075 *
00076 *> \ingroup aux_lin
00077 *
00078 *  =====================================================================
00079       SUBROUTINE XLAENV( ISPEC, NVALUE )
00080 *
00081 *  -- LAPACK test routine (version 3.4.0) --
00082 *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
00083 *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
00084 *     November 2011
00085 *
00086 *     .. Scalar Arguments ..
00087       INTEGER            ISPEC, NVALUE
00088 *     ..
00089 *
00090 *  =====================================================================
00091 *
00092 *     .. Arrays in Common ..
00093       INTEGER            IPARMS( 100 )
00094 *     ..
00095 *     .. Common blocks ..
00096       COMMON             / CLAENV / IPARMS
00097 *     ..
00098 *     .. Save statement ..
00099       SAVE               / CLAENV /
00100 *     ..
00101 *     .. Executable Statements ..
00102 *
00103       IF( ISPEC.GE.1 .AND. ISPEC.LE.9 ) THEN
00104          IPARMS( ISPEC ) = NVALUE
00105       END IF
00106 *
00107       RETURN
00108 *
00109 *     End of XLAENV
00110 *
00111       END
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