1 | *> \brief \b SLAMCH |
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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 | * REAL FUNCTION SLAMCH( CMACH ) |
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12 | * |
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13 | * .. Scalar Arguments .. |
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14 | * CHARACTER CMACH |
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15 | * .. |
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16 | * |
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17 | * |
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18 | *> \par Purpose: |
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19 | * ============= |
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20 | *> |
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21 | *> \verbatim |
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22 | *> |
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23 | *> SLAMCH determines single precision machine parameters. |
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24 | *> \endverbatim |
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25 | * |
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26 | * Arguments: |
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27 | * ========== |
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28 | * |
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29 | *> \param[in] CMACH |
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30 | *> \verbatim |
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31 | *> Specifies the value to be returned by SLAMCH: |
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32 | *> = 'E' or 'e', SLAMCH := eps |
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33 | *> = 'S' or 's , SLAMCH := sfmin |
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34 | *> = 'B' or 'b', SLAMCH := base |
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35 | *> = 'P' or 'p', SLAMCH := eps*base |
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36 | *> = 'N' or 'n', SLAMCH := t |
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37 | *> = 'R' or 'r', SLAMCH := rnd |
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38 | *> = 'M' or 'm', SLAMCH := emin |
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39 | *> = 'U' or 'u', SLAMCH := rmin |
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40 | *> = 'L' or 'l', SLAMCH := emax |
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41 | *> = 'O' or 'o', SLAMCH := rmax |
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42 | *> where |
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43 | *> eps = relative machine precision |
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44 | *> sfmin = safe minimum, such that 1/sfmin does not overflow |
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45 | *> base = base of the machine |
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46 | *> prec = eps*base |
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47 | *> t = number of (base) digits in the mantissa |
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48 | *> rnd = 1.0 when rounding occurs in addition, 0.0 otherwise |
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49 | *> emin = minimum exponent before (gradual) underflow |
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50 | *> rmin = underflow threshold - base**(emin-1) |
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51 | *> emax = largest exponent before overflow |
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52 | *> rmax = overflow threshold - (base**emax)*(1-eps) |
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53 | *> \endverbatim |
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54 | * |
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55 | * Authors: |
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56 | * ======== |
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57 | * |
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58 | *> \author Univ. of Tennessee |
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59 | *> \author Univ. of California Berkeley |
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60 | *> \author Univ. of Colorado Denver |
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61 | *> \author NAG Ltd. |
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62 | * |
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63 | *> \date November 2011 |
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64 | * |
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65 | *> \ingroup auxOTHERauxiliary |
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66 | * |
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67 | * ===================================================================== |
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68 | REAL FUNCTION SLAMCH( CMACH ) |
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69 | * |
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70 | * -- LAPACK auxiliary routine (version 3.4.0) -- |
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71 | * -- LAPACK is a software package provided by Univ. of Tennessee, -- |
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72 | * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- |
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73 | * November 2011 |
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74 | * |
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75 | * .. Scalar Arguments .. |
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76 | CHARACTER CMACH |
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77 | * .. |
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78 | * |
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79 | * ===================================================================== |
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80 | * |
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81 | * .. Parameters .. |
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82 | REAL ONE, ZERO |
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83 | PARAMETER ( ONE = 1.0E+0, ZERO = 0.0E+0 ) |
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84 | * .. |
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85 | * .. Local Scalars .. |
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86 | REAL RND, EPS, SFMIN, SMALL, RMACH |
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87 | * .. |
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88 | * .. External Functions .. |
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89 | LOGICAL LSAME |
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90 | EXTERNAL LSAME |
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91 | * .. |
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92 | * .. Intrinsic Functions .. |
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93 | INTRINSIC DIGITS, EPSILON, HUGE, MAXEXPONENT, |
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94 | $ MINEXPONENT, RADIX, TINY |
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95 | * .. |
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96 | * .. Executable Statements .. |
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97 | * |
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98 | * |
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99 | * Assume rounding, not chopping. Always. |
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100 | * |
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101 | RND = ONE |
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102 | * |
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103 | IF( ONE.EQ.RND ) THEN |
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104 | EPS = EPSILON(ZERO) * 0.5 |
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105 | ELSE |
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106 | EPS = EPSILON(ZERO) |
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107 | END IF |
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108 | * |
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109 | IF( LSAME( CMACH, 'E' ) ) THEN |
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110 | RMACH = EPS |
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111 | ELSE IF( LSAME( CMACH, 'S' ) ) THEN |
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112 | SFMIN = TINY(ZERO) |
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113 | SMALL = ONE / HUGE(ZERO) |
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114 | IF( SMALL.GE.SFMIN ) THEN |
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115 | * |
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116 | * Use SMALL plus a bit, to avoid the possibility of rounding |
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117 | * causing overflow when computing 1/sfmin. |
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118 | * |
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119 | SFMIN = SMALL*( ONE+EPS ) |
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120 | END IF |
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121 | RMACH = SFMIN |
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122 | ELSE IF( LSAME( CMACH, 'B' ) ) THEN |
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123 | RMACH = RADIX(ZERO) |
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124 | ELSE IF( LSAME( CMACH, 'P' ) ) THEN |
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125 | RMACH = EPS * RADIX(ZERO) |
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126 | ELSE IF( LSAME( CMACH, 'N' ) ) THEN |
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127 | RMACH = DIGITS(ZERO) |
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128 | ELSE IF( LSAME( CMACH, 'R' ) ) THEN |
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129 | RMACH = RND |
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130 | ELSE IF( LSAME( CMACH, 'M' ) ) THEN |
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131 | RMACH = MINEXPONENT(ZERO) |
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132 | ELSE IF( LSAME( CMACH, 'U' ) ) THEN |
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133 | RMACH = tiny(zero) |
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134 | ELSE IF( LSAME( CMACH, 'L' ) ) THEN |
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135 | RMACH = MAXEXPONENT(ZERO) |
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136 | ELSE IF( LSAME( CMACH, 'O' ) ) THEN |
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137 | RMACH = HUGE(ZERO) |
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138 | ELSE |
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139 | RMACH = ZERO |
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140 | END IF |
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141 | * |
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142 | SLAMCH = RMACH |
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143 | RETURN |
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144 | * |
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145 | * End of SLAMCH |
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146 | * |
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147 | END |
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148 | ************************************************************************ |
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149 | *> \brief \b SLAMC3 |
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150 | *> \details |
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151 | *> \b Purpose: |
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152 | *> \verbatim |
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153 | *> SLAMC3 is intended to force A and B to be stored prior to doing |
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154 | *> the addition of A and B , for use in situations where optimizers |
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155 | *> might hold one of these in a register. |
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156 | *> \endverbatim |
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157 | *> \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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158 | *> \date November 2011 |
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159 | *> \ingroup auxOTHERauxiliary |
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160 | *> |
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161 | *> \param[in] A |
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162 | *> \verbatim |
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163 | *> \endverbatim |
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164 | *> |
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165 | *> \param[in] B |
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166 | *> \verbatim |
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167 | *> The values A and B. |
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168 | *> \endverbatim |
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169 | *> |
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170 | * |
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171 | REAL FUNCTION SLAMC3( A, B ) |
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172 | * |
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173 | * -- LAPACK auxiliary routine (version 3.4.0) -- |
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174 | * Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. |
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175 | * November 2010 |
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176 | * |
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177 | * .. Scalar Arguments .. |
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178 | REAL A, B |
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179 | * .. |
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180 | * ===================================================================== |
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181 | * |
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182 | * .. Executable Statements .. |
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183 | * |
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184 | SLAMC3 = A + B |
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185 | * |
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186 | RETURN |
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187 | * |
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188 | * End of SLAMC3 |
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189 | * |
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190 | END |
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191 | * |
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192 | ************************************************************************ |
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