PLASMA  2.4.5
PLASMA - Parallel Linear Algebra for Scalable Multi-core Architectures
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xlaenv.f
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1  SUBROUTINE xlaenv( ISPEC, NVALUE )
2 *
3 * -- LAPACK auxiliary routine (version 3.1) --
4 * Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
5 * November 2006
6 *
7 * .. Scalar Arguments ..
8  INTEGER ispec, nvalue
9 * ..
10 *
11 * Purpose
12 * =======
13 *
14 * XLAENV sets certain machine- and problem-dependent quantities
15 * which will later be retrieved by ILAENV.
16 *
17 * Arguments
18 * =========
19 *
20 * ISPEC (input) INTEGER
21 * Specifies the parameter to be set in the COMMON array IPARMS.
22 * = 1: the optimal blocksize; if this value is 1, an unblocked
23 * algorithm will give the best performance.
24 * = 2: the minimum block size for which the block routine
25 * should be used; if the usable block size is less than
26 * this value, an unblocked routine should be used.
27 * = 3: the crossover point (in a block routine, for N less
28 * than this value, an unblocked routine should be used)
29 * = 4: the number of shifts, used in the nonsymmetric
30 * eigenvalue routines
31 * = 5: the minimum column dimension for blocking to be used;
32 * rectangular blocks must have dimension at least k by m,
33 * where k is given by ILAENV(2,...) and m by PLASMA_
34 * ILAENV(5,...)
35 * = 6: the crossover point for the SVD (when reducing an m by n
36 * matrix to bidiagonal form, if max(m,n)/min(m,n) exceeds
37 * this value, a QR factorization is used first to reduce
38 * the matrix to a triangular form)
39 * = 7: the number of processors
40 * = 8: another crossover point, for the multishift QR and QZ
41 * methods for nonsymmetric eigenvalue problems.
42 * = 9: maximum size of the subproblems at the bottom of the
43 * computation tree in the divide-and-conquer algorithm
44 * (used by xGELSD and xGESDD)
45 * =10: ieee NaN arithmetic can be trusted not to trap
46 * =11: infinity arithmetic can be trusted not to trap
47 *
48 * NVALUE (input) INTEGER
49 * The value of the parameter specified by ISPEC.
50 *
51 * =====================================================================
52 *
53 * .. Arrays in Common ..
54  INTEGER iparms( 100 )
55 * ..
56 * .. Common blocks ..
57  common / claenv / iparms
58 * ..
59 * .. Save statement ..
60  SAVE / claenv /
61 * ..
62 * .. Executable Statements ..
63 *
64  IF( ispec.GE.1 .AND. ispec.LE.9 ) THEN
65  iparms( ispec ) = nvalue
66  END IF
67 *
68  return
69 *
70 * End of XLAENV
71 *
72  END