◆ 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
!>          12 <= ISPEC <= 16:
!>               xHSEQR or one of its subroutines,
!>               see IPARMQ for detailed explanation
!>

[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 80 of file xlaenv.f.

*
*  -- LAPACK test routine --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*
*     .. Scalar Arguments ..
      INTEGER            ISPEC, NVALUE
*     ..
*
*  =====================================================================
*
*     .. Arrays in Common ..
      INTEGER            IPARMS( 100 )
*     ..
*     .. Common blocks ..
      COMMON             / claenv / iparms
*     ..
*     .. Save statement ..
      SAVE               / claenv /
*     ..
*     .. Executable Statements ..
*
      IF( ispec.GE.1 .AND. ispec.LE.16 ) THEN
         iparms( ispec ) = nvalue
      END IF
*
      RETURN
*
*     End of XLAENV
*

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