[136] | 1 | *> \brief \b DLAMCH
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| 2 | *
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| 3 | * =========== DOCUMENTATION ===========
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| 4 | *
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| 5 | * Online html documentation available at
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| 6 | * http://www.netlib.org/lapack/explore-html/
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| 7 | *
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| 8 | * Definition:
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| 9 | * ===========
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| 10 | *
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| 11 | * DOUBLE PRECISION FUNCTION DLAMCH( CMACH )
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| 12 | *
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| 13 | *
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| 14 | *> \par Purpose:
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| 15 | * =============
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| 16 | *>
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| 17 | *> \verbatim
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| 18 | *>
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| 19 | *> DLAMCH determines double precision machine parameters.
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| 20 | *> \endverbatim
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| 21 | *
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| 22 | * Arguments:
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| 23 | * ==========
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| 24 | *
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| 25 | *> \param[in] CMACH
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| 26 | *> \verbatim
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| 27 | *> Specifies the value to be returned by DLAMCH:
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| 28 | *> = 'E' or 'e', DLAMCH := eps
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| 29 | *> = 'S' or 's , DLAMCH := sfmin
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| 30 | *> = 'B' or 'b', DLAMCH := base
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| 31 | *> = 'P' or 'p', DLAMCH := eps*base
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| 32 | *> = 'N' or 'n', DLAMCH := t
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| 33 | *> = 'R' or 'r', DLAMCH := rnd
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| 34 | *> = 'M' or 'm', DLAMCH := emin
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| 35 | *> = 'U' or 'u', DLAMCH := rmin
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| 36 | *> = 'L' or 'l', DLAMCH := emax
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| 37 | *> = 'O' or 'o', DLAMCH := rmax
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| 38 | *> where
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| 39 | *> eps = relative machine precision
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| 40 | *> sfmin = safe minimum, such that 1/sfmin does not overflow
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| 41 | *> base = base of the machine
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| 42 | *> prec = eps*base
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| 43 | *> t = number of (base) digits in the mantissa
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| 44 | *> rnd = 1.0 when rounding occurs in addition, 0.0 otherwise
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| 45 | *> emin = minimum exponent before (gradual) underflow
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| 46 | *> rmin = underflow threshold - base**(emin-1)
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| 47 | *> emax = largest exponent before overflow
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| 48 | *> rmax = overflow threshold - (base**emax)*(1-eps)
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| 49 | *> \endverbatim
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| 50 | *
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| 51 | * Authors:
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| 52 | * ========
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| 53 | *
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| 54 | *> \author Univ. of Tennessee
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| 55 | *> \author Univ. of California Berkeley
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| 56 | *> \author Univ. of Colorado Denver
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| 57 | *> \author NAG Ltd.
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| 58 | *
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| 59 | *> \date November 2011
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| 60 | *
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| 61 | *> \ingroup auxOTHERauxiliary
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| 62 | *
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| 63 | * =====================================================================
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| 64 | DOUBLE PRECISION FUNCTION DLAMCH( CMACH )
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| 65 | *
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| 66 | * -- LAPACK auxiliary routine (version 3.4.0) --
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| 67 | * -- LAPACK is a software package provided by Univ. of Tennessee, --
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| 68 | * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
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| 69 | * November 2011
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| 70 | *
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| 71 | * .. Scalar Arguments ..
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| 72 | CHARACTER CMACH
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| 73 | * ..
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| 74 | *
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| 75 | * =====================================================================
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| 76 | *
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| 77 | * .. Parameters ..
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| 78 | DOUBLE PRECISION ONE, ZERO
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| 79 | PARAMETER ( ONE = 1.0D+0, ZERO = 0.0D+0 )
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| 80 | * ..
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| 81 | * .. Local Scalars ..
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| 82 | DOUBLE PRECISION RND, EPS, SFMIN, SMALL, RMACH
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| 83 | * ..
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| 84 | * .. External Functions ..
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| 85 | LOGICAL LSAME
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| 86 | EXTERNAL LSAME
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| 87 | * ..
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| 88 | * .. Intrinsic Functions ..
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| 89 | INTRINSIC DIGITS, EPSILON, HUGE, MAXEXPONENT,
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| 90 | $ MINEXPONENT, RADIX, TINY
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| 91 | * ..
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| 92 | * .. Executable Statements ..
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| 93 | *
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| 94 | *
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| 95 | * Assume rounding, not chopping. Always.
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| 96 | *
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| 97 | RND = ONE
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| 98 | *
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| 99 | IF( ONE.EQ.RND ) THEN
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| 100 | EPS = EPSILON(ZERO) * 0.5
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| 101 | ELSE
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| 102 | EPS = EPSILON(ZERO)
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| 103 | END IF
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| 104 | *
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| 105 | IF( LSAME( CMACH, 'E' ) ) THEN
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| 106 | RMACH = EPS
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| 107 | ELSE IF( LSAME( CMACH, 'S' ) ) THEN
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| 108 | SFMIN = TINY(ZERO)
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| 109 | SMALL = ONE / HUGE(ZERO)
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| 110 | IF( SMALL.GE.SFMIN ) THEN
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| 111 | *
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| 112 | * Use SMALL plus a bit, to avoid the possibility of rounding
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| 113 | * causing overflow when computing 1/sfmin.
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| 114 | *
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| 115 | SFMIN = SMALL*( ONE+EPS )
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| 116 | END IF
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| 117 | RMACH = SFMIN
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| 118 | ELSE IF( LSAME( CMACH, 'B' ) ) THEN
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| 119 | RMACH = RADIX(ZERO)
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| 120 | ELSE IF( LSAME( CMACH, 'P' ) ) THEN
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| 121 | RMACH = EPS * RADIX(ZERO)
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| 122 | ELSE IF( LSAME( CMACH, 'N' ) ) THEN
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| 123 | RMACH = DIGITS(ZERO)
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| 124 | ELSE IF( LSAME( CMACH, 'R' ) ) THEN
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| 125 | RMACH = RND
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| 126 | ELSE IF( LSAME( CMACH, 'M' ) ) THEN
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| 127 | RMACH = MINEXPONENT(ZERO)
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| 128 | ELSE IF( LSAME( CMACH, 'U' ) ) THEN
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| 129 | RMACH = tiny(zero)
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| 130 | ELSE IF( LSAME( CMACH, 'L' ) ) THEN
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| 131 | RMACH = MAXEXPONENT(ZERO)
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| 132 | ELSE IF( LSAME( CMACH, 'O' ) ) THEN
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| 133 | RMACH = HUGE(ZERO)
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| 134 | ELSE
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| 135 | RMACH = ZERO
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| 136 | END IF
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| 137 | *
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| 138 | DLAMCH = RMACH
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| 139 | RETURN
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| 140 | *
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| 141 | * End of DLAMCH
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| 142 | *
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| 143 | END
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| 144 | ************************************************************************
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| 145 | *> \brief \b DLAMC3
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| 146 | *> \details
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| 147 | *> \b Purpose:
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| 148 | *> \verbatim
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| 149 | *> DLAMC3 is intended to force A and B to be stored prior to doing
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| 150 | *> the addition of A and B , for use in situations where optimizers
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| 151 | *> might hold one of these in a register.
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| 152 | *> \endverbatim
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| 153 | *> \author LAPACK is a software package provided by Univ. of Tennessee, Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..
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| 154 | *> \date November 2011
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| 155 | *> \ingroup auxOTHERauxiliary
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| 156 | *>
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| 157 | *> \param[in] A
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| 158 | *> \verbatim
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| 159 | *> A is a DOUBLE PRECISION
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| 160 | *> \endverbatim
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| 161 | *>
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| 162 | *> \param[in] B
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| 163 | *> \verbatim
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| 164 | *> B is a DOUBLE PRECISION
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| 165 | *> The values A and B.
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| 166 | *> \endverbatim
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| 167 | *>
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| 168 | DOUBLE PRECISION FUNCTION DLAMC3( A, B )
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| 169 | *
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| 170 | * -- LAPACK auxiliary routine (version 3.4.0) --
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| 171 | * Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
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| 172 | * November 2010
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| 173 | *
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| 174 | * .. Scalar Arguments ..
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| 175 | DOUBLE PRECISION A, B
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| 176 | * ..
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| 177 | * =====================================================================
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| 178 | *
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| 179 | * .. Executable Statements ..
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| 180 | *
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| 181 | DLAMC3 = A + B
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| 182 | *
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| 183 | RETURN
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| 184 | *
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| 185 | * End of DLAMC3
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| 186 | *
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| 187 | END
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| 188 | *
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| 189 | ************************************************************************
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