LAPACK  3.10.1
LAPACK: Linear Algebra PACKage

◆ xlaenv()

subroutine xlaenv ( integer  ISPEC,
integer  NVALUE 
)

XLAENV

Purpose:
 XLAENV sets certain machine- and problem-dependent quantities
 which will later be retrieved by ILAENV.
Parameters
[in]ISPEC
          ISPEC is INTEGER
          Specifies the parameter to be set in the COMMON array IPARMS.
          = 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: another 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
               (used by xGELSD and xGESDD)
          =10: ieee NaN arithmetic can be trusted not to trap
          =11: infinity arithmetic can be trusted not to trap
[in]NVALUE
          NVALUE is INTEGER
          The value of the parameter specified by ISPEC.
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.

Definition at line 77 of file xlaenv.f.

78 *
79 * -- LAPACK test routine --
80 * -- LAPACK is a software package provided by Univ. of Tennessee, --
81 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
82 *
83 * .. Scalar Arguments ..
84  INTEGER ISPEC, NVALUE
85 * ..
86 *
87 * =====================================================================
88 *
89 * .. Arrays in Common ..
90  INTEGER IPARMS( 100 )
91 * ..
92 * .. Common blocks ..
93  COMMON / claenv / iparms
94 * ..
95 * .. Save statement ..
96  SAVE / claenv /
97 * ..
98 * .. Executable Statements ..
99 *
100  IF( ispec.GE.1 .AND. ispec.LE.9 ) THEN
101  iparms( ispec ) = nvalue
102  END IF
103 *
104  RETURN
105 *
106 * End of XLAENV
107 *