LAPACK  3.8.0
LAPACK: Linear Algebra PACKage
dget06.f
Go to the documentation of this file.
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 *> \date December 2016
52 *
53 *> \ingroup double_lin
54 *
55 * =====================================================================
56  DOUBLE PRECISION FUNCTION dget06( RCOND, RCONDC )
57 *
58 * -- LAPACK test routine (version 3.7.0) --
59 * -- LAPACK is a software package provided by Univ. of Tennessee, --
60 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
61 * December 2016
62 *
63 * .. Scalar Arguments ..
64  DOUBLE PRECISION RCOND, RCONDC
65 * ..
66 *
67 * =====================================================================
68 *
69 * .. Parameters ..
70  DOUBLE PRECISION ZERO, ONE
71  parameter( zero = 0.0d+0, one = 1.0d+0 )
72 * ..
73 * .. Local Scalars ..
74  DOUBLE PRECISION EPS, RAT
75 * ..
76 * .. External Functions ..
77  DOUBLE PRECISION DLAMCH
78  EXTERNAL dlamch
79 * ..
80 * .. Intrinsic Functions ..
81  INTRINSIC max, min
82 * ..
83 * .. Executable Statements ..
84 *
85  eps = dlamch( 'Epsilon' )
86  IF( rcond.GT.zero ) THEN
87  IF( rcondc.GT.zero ) THEN
88  rat = max( rcond, rcondc ) / min( rcond, rcondc ) -
89  $ ( one-eps )
90  ELSE
91  rat = rcond / eps
92  END IF
93  ELSE
94  IF( rcondc.GT.zero ) THEN
95  rat = rcondc / eps
96  ELSE
97  rat = zero
98  END IF
99  END IF
100  dget06 = rat
101  RETURN
102 *
103 * End of DGET06
104 *
105  END
double precision function dget06(RCOND, RCONDC)
DGET06
Definition: dget06.f:57