LAPACK  3.10.0
LAPACK: Linear Algebra PACKage
dget06.f
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1 *> \brief \b DGET06
2 *
3 * =========== DOCUMENTATION ===========
4 *
5 * Online html documentation available at
6 * http://www.netlib.org/lapack/explore-html/
7 *
8 * Definition:
9 * ===========
10 *
11 * DOUBLE PRECISION FUNCTION DGET06( RCOND, RCONDC )
12 *
13 * .. Scalar Arguments ..
14 * DOUBLE PRECISION RCOND, RCONDC
15 * ..
16 *
17 *
18 *> \par Purpose:
19 * =============
20 *>
21 *> \verbatim
22 *>
23 *> DGET06 computes a test ratio to compare two values for RCOND.
24 *> \endverbatim
25 *
26 * Arguments:
27 * ==========
28 *
29 *> \param[in] RCOND
30 *> \verbatim
31 *> RCOND is DOUBLE PRECISION
32 *> The estimate of the reciprocal of the condition number of A,
33 *> as computed by DGECON.
34 *> \endverbatim
35 *>
36 *> \param[in] RCONDC
37 *> \verbatim
38 *> RCONDC is DOUBLE PRECISION
39 *> The reciprocal of the condition number of A, computed as
40 *> ( 1/norm(A) ) / norm(inv(A)).
41 *> \endverbatim
42 *
43 * Authors:
44 * ========
45 *
46 *> \author Univ. of Tennessee
47 *> \author Univ. of California Berkeley
48 *> \author Univ. of Colorado Denver
49 *> \author NAG Ltd.
50 *
51 *> \ingroup double_lin
52 *
53 * =====================================================================
54  DOUBLE PRECISION FUNCTION dget06( RCOND, RCONDC )
55 *
56 * -- LAPACK test routine --
57 * -- LAPACK is a software package provided by Univ. of Tennessee, --
58 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
59 *
60 * .. Scalar Arguments ..
61  DOUBLE PRECISION rcond, rcondc
62 * ..
63 *
64 * =====================================================================
65 *
66 * .. Parameters ..
67  DOUBLE PRECISION zero, one
68  parameter( zero = 0.0d+0, one = 1.0d+0 )
69 * ..
70 * .. Local Scalars ..
71  DOUBLE PRECISION eps, rat
72 * ..
73 * .. External Functions ..
74  DOUBLE PRECISION dlamch
75  EXTERNAL dlamch
76 * ..
77 * .. Intrinsic Functions ..
78  INTRINSIC max, min
79 * ..
80 * .. Executable Statements ..
81 *
82  eps = dlamch( 'Epsilon' )
83  IF( rcond.GT.zero ) THEN
84  IF( rcondc.GT.zero ) THEN
85  rat = max( rcond, rcondc ) / min( rcond, rcondc ) -
86  $ ( one-eps )
87  ELSE
88  rat = rcond / eps
89  END IF
90  ELSE
91  IF( rcondc.GT.zero ) THEN
92  rat = rcondc / eps
93  ELSE
94  rat = zero
95  END IF
96  END IF
97  dget06 = rat
98  RETURN
99 *
100 * End of DGET06
101 *
102  END
double precision function dlamch(CMACH)
DLAMCH
Definition: dlamch.f:69
double precision function dget06(RCOND, RCONDC)
DGET06
Definition: dget06.f:55