numeric-linalg

001
002
003
004
005
006
007
008
009
010
011
012
013
014
015
016
017
018
019
020
021
022
023
024
025
026
027
028
029
030
031
032
033
034
035
036
037
038
039
040
041
042
043
044
045
046
047
048
049
050
051
052
053
054
055
056
057
058
059
060
061
062
063
064
065
066
067
068
069
070
071
072
073
074
075
076
077
078
079
080
081
082
083
084
085
086
087
088
089
090
091
092
093
094
095
096
097
098
099
100
101
102

*> \brief \b SGET06
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*  Definition:
*  ===========
*
*       REAL             FUNCTION SGET06( RCOND, RCONDC )
*
*       .. Scalar Arguments ..
*       REAL               RCOND, RCONDC
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> SGET06 computes a test ratio to compare two values for RCOND.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] RCOND
*> \verbatim
*>          RCOND is REAL
*>          The estimate of the reciprocal of the condition number of A,
*>          as computed by SGECON.
*> \endverbatim
*>
*> \param[in] RCONDC
*> \verbatim
*>          RCONDC is REAL
*>          The reciprocal of the condition number of A, computed as
*>          ( 1/norm(A) ) / norm(inv(A)).
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \ingroup single_lin
*
*  =====================================================================
      REAL             FUNCTION SGET06( RCOND, RCONDC )
*
*  -- 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 ..
      REAL               RCOND, RCONDC
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      REAL               ZERO, ONE
      PARAMETER          ( ZERO = 0.0E+0, ONE = 1.0E+0 )
*     ..
*     .. Local Scalars ..
      REAL               EPS, RAT
*     ..
*     .. External Functions ..
      REAL               SLAMCH
      EXTERNAL           SLAMCH
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, MIN
*     ..
*     .. Executable Statements ..
*
      EPS = SLAMCH( 'Epsilon' )
      IF( RCOND.GT.ZERO ) THEN
         IF( RCONDC.GT.ZERO ) THEN
            RAT = MAX( RCOND, RCONDC ) / MIN( RCOND, RCONDC ) -
     $            ( ONE-EPS )
         ELSE
            RAT = RCOND / EPS
         END IF
      ELSE
         IF( RCONDC.GT.ZERO ) THEN
            RAT = RCONDC / EPS
         ELSE
            RAT = ZERO
         END IF
      END IF
      SGET06 = RAT
      RETURN
*
*     End of SGET06
*
      END