dd/d66/dget06_8f_source.html

00001       DOUBLE PRECISION FUNCTION DGET06( RCOND, RCONDC )
00002 *
00003 *  -- LAPACK test routine (version 3.1) --
00004 *     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
00005 *     November 2006
00006 *
00007 *     .. Scalar Arguments ..
00008       DOUBLE PRECISION   RCOND, RCONDC
00009 *     ..
00010 *
00011 *  Purpose
00012 *  =======
00013 *
00014 *  DGET06 computes a test ratio to compare two values for RCOND.
00015 *
00016 *  Arguments
00017 *  ==========
00018 *
00019 *  RCOND   (input) DOUBLE PRECISION
00020 *          The estimate of the reciprocal of the condition number of A,
00021 *          as computed by DGECON.
00022 *
00023 *  RCONDC  (input) DOUBLE PRECISION
00024 *          The reciprocal of the condition number of A, computed as
00025 *          ( 1/norm(A) ) / norm(inv(A)).
00026 *
00027 *  =====================================================================
00028 *
00029 *     .. Parameters ..
00030       DOUBLE PRECISION   ZERO, ONE
00031       PARAMETER          ( ZERO = 0.0D+0, ONE = 1.0D+0 )
00032 *     ..
00033 *     .. Local Scalars ..
00034       DOUBLE PRECISION   EPS, RAT
00035 *     ..
00036 *     .. External Functions ..
00037       DOUBLE PRECISION   DLAMCH
00038       EXTERNAL           DLAMCH
00039 *     ..
00040 *     .. Intrinsic Functions ..
00041       INTRINSIC          MAX, MIN
00042 *     ..
00043 *     .. Executable Statements ..
00044 *
00045       EPS = DLAMCH( 'Epsilon' )
00046       IF( RCOND.GT.ZERO ) THEN
00047          IF( RCONDC.GT.ZERO ) THEN
00048             RAT = MAX( RCOND, RCONDC ) / MIN( RCOND, RCONDC ) -
00049      $            ( ONE-EPS )
00050          ELSE
00051             RAT = RCOND / EPS
00052          END IF
00053       ELSE
00054          IF( RCONDC.GT.ZERO ) THEN
00055             RAT = RCONDC / EPS
00056          ELSE
00057             RAT = ZERO
00058          END IF
00059       END IF
00060       DGET06 = RAT
00061       RETURN
00062 *
00063 *     End of DGET06
00064 *
00065       END