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1 // Range.cc -*- C++ -*- |
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2 /* |
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3 |
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4 Copyright (C) 1992, 1993, 1994, 1995 John W. Eaton |
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5 |
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6 This file is part of Octave. |
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7 |
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8 Octave is free software; you can redistribute it and/or modify it |
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9 under the terms of the GNU General Public License as published by the |
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10 Free Software Foundation; either version 2, or (at your option) any |
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11 later version. |
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12 |
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13 Octave is distributed in the hope that it will be useful, but WITHOUT |
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14 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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16 for more details. |
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17 |
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18 You should have received a copy of the GNU General Public License |
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19 along with Octave; see the file COPYING. If not, write to the Free |
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20 Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
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21 |
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22 */ |
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23 |
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24 #if defined (__GNUG__) |
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25 #pragma implementation |
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26 #endif |
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27 |
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28 #ifdef HAVE_CONFIG_H |
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29 #include <config.h> |
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30 #endif |
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31 |
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32 #include <iostream.h> |
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33 #include <limits.h> |
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34 |
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35 #include "Range.h" |
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36 #include "dMatrix.h" |
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37 |
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38 Matrix |
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39 Range::matrix_value (void) const |
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40 { |
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41 Matrix retval; |
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42 |
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43 if (rng_nelem > 0) |
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44 { |
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45 retval.resize (1, rng_nelem); |
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46 double b = rng_base; |
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47 double increment = rng_inc; |
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48 for (int i = 0; i < rng_nelem; i++) |
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49 retval.elem (0, i) = b + i * increment; |
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50 } |
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51 |
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52 return retval; |
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53 } |
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54 |
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208
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55 // NOTE: max and min only return useful values if nelem > 0. |
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56 |
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57 double |
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58 Range::min (void) const |
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59 { |
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60 double retval = 0.0; |
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61 if (rng_nelem > 0) |
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62 { |
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63 if (rng_inc > 0) |
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64 retval = rng_base; |
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65 else |
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66 retval = rng_base + (rng_nelem - 1) * rng_inc; |
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67 } |
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68 return retval; |
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69 } |
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70 |
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71 double |
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72 Range::max (void) const |
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73 { |
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74 double retval = 0.0; |
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75 if (rng_nelem > 0) |
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76 { |
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77 if (rng_inc > 0) |
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78 retval = rng_base + (rng_nelem - 1) * rng_inc; |
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79 else |
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80 retval = rng_base; |
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81 } |
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82 return retval; |
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83 } |
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84 |
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85 void |
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86 Range::sort (void) |
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87 { |
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88 if (rng_base > rng_limit && rng_inc < 0.0) |
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89 { |
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90 double tmp = rng_base; |
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91 rng_base = min (); |
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92 rng_limit = tmp; |
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93 rng_inc = -rng_inc; |
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94 } |
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95 } |
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96 |
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97 void |
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98 Range::print_range (void) |
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99 { |
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100 cerr << "Range: rng_base = " << rng_base |
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101 << " rng_limit " << rng_limit |
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102 << " rng_inc " << rng_inc |
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103 << " rng_nelem " << rng_nelem << "\n"; |
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104 } |
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105 |
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106 ostream& |
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107 operator << (ostream& os, const Range& a) |
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108 { |
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109 double b = a.base (); |
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110 double increment = a.inc (); |
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111 int num_elem = a.nelem (); |
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112 |
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113 for (int i = 0; i < num_elem; i++) |
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114 os << b + i * increment << " "; |
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115 |
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116 os << "\n"; |
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117 |
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118 return os; |
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119 } |
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120 |
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121 istream& |
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122 operator >> (istream& is, Range& a) |
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123 { |
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124 is >> a.rng_base; |
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125 if (is) |
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126 { |
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127 is >> a.rng_limit; |
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128 if (is) |
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129 { |
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130 is >> a.rng_inc; |
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131 a.rng_nelem = a.nelem_internal (); |
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132 } |
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133 } |
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134 |
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135 return is; |
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136 } |
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137 |
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138 int |
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139 Range::nelem_internal (void) const |
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140 { |
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141 // Find an approximate number of intervals, then do the best we can to |
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142 // find the number of intervals that we would get if we had done |
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143 // something like |
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144 // |
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145 // nelem = 0; |
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146 // while (base + nelem * inc <= limit) |
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147 // nelem++; |
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148 // |
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149 // (for limit > base && inc > 0) |
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150 // |
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151 // The number of elements in the range is one greater than the number |
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152 // of intervals. |
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153 |
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154 // We can't have more than INT_MAX elements in the range. |
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155 |
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156 double d_n_intervals = (rng_limit - rng_base) / rng_inc; |
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157 int max_intervals = INT_MAX - 1; |
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158 double d_max_val = (double) max_intervals; |
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159 |
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160 if (d_n_intervals > d_max_val) |
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161 return -1; |
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162 |
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163 int n_intervals = (d_n_intervals > 0) |
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164 ? ((int) (d_n_intervals + 0.5)) |
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165 : ((int) (d_n_intervals - 0.5)); |
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166 |
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167 if (rng_limit > rng_base && rng_inc > 0) |
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168 { |
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169 // Our approximation may have been too big. |
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170 |
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171 while (rng_base + n_intervals * rng_inc > rng_limit && n_intervals > 0) |
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172 n_intervals--; |
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173 |
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174 // Now that we are close, get the actual number. Try to avoid |
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175 // problems with extended precision registers. |
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176 |
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177 for (;;) |
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178 { |
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179 volatile double tmp_inc = (n_intervals + 1) * rng_inc; |
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180 volatile double tmp_val = rng_base + tmp_inc; |
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181 if (tmp_val <= rng_limit && n_intervals < max_intervals) |
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182 n_intervals++; |
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183 else |
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184 break; |
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185 } |
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186 } |
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187 else if (rng_limit < rng_base && rng_inc < 0) |
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188 { |
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189 // Our approximation may have been too big. |
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190 |
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191 while (rng_base + n_intervals * rng_inc < rng_limit && n_intervals > 0) |
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192 n_intervals--; |
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193 |
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194 // Now that we are close, get the actual number. Try to avoid |
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195 // problems with extended precision registers. |
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196 |
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398
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197 for (;;) |
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198 { |
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199 volatile double tmp_inc = (n_intervals + 1) * rng_inc; |
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200 volatile double tmp_val = rng_base + tmp_inc; |
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201 if (tmp_val >= rng_limit && n_intervals < max_intervals) |
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202 n_intervals++; |
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203 else |
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204 break; |
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205 } |
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206 } |
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207 else if (rng_limit == rng_base) |
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208 n_intervals = 0; |
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209 else |
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210 n_intervals = -1; |
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211 |
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212 return (n_intervals >= max_intervals) ? -1 : n_intervals + 1; |
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213 } |
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214 |
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215 /* |
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216 ;;; Local Variables: *** |
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217 ;;; mode: C++ *** |
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218 ;;; page-delimiter: "^/\\*" *** |
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219 ;;; End: *** |
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220 */ |
