LAPACK  3.6.1 LAPACK: Linear Algebra PACKage
 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.```
Date
November 2011

Definition at line 83 of file xlaenv.f.

83 *
84 * -- LAPACK test routine (version 3.4.0) --
85 * -- LAPACK is a software package provided by Univ. of Tennessee, --
86 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
87 * November 2011
88 *
89 * .. Scalar Arguments ..
90  INTEGER ispec, nvalue
91 * ..
92 *
93 * =====================================================================
94 *
95 * .. Arrays in Common ..
96  INTEGER iparms( 100 )
97 * ..
98 * .. Common blocks ..
99  COMMON / claenv / iparms
100 * ..
101 * .. Save statement ..
102  SAVE / claenv /
103 * ..
104 * .. Executable Statements ..
105 *
106  IF( ispec.GE.1 .AND. ispec.LE.16 ) THEN
107  iparms( ispec ) = nvalue
108  END IF
109 *
110  RETURN
111 *
112 * End of XLAENV
113 *