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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 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, 675 Mass Ave, Cambridge, MA 02139, USA. |
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21 |
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22 */ |
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23 |
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24 #ifdef __GNUG__ |
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25 #pragma implementation |
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26 #endif |
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27 |
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28 #include <limits.h> |
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29 |
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30 #include "Range.h" |
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31 |
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208
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32 // NOTE: max and min only return useful values if nelem > 0. |
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33 |
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34 double |
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35 Range::min (void) const |
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36 { |
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37 double retval = 0.0; |
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38 if (rng_nelem > 0) |
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39 { |
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40 if (rng_inc > 0) |
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41 retval = rng_base; |
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42 else |
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43 retval = rng_base + (rng_nelem - 1) * rng_inc; |
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44 } |
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45 return retval; |
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46 } |
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47 |
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48 double |
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49 Range::max (void) const |
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50 { |
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51 double retval = 0.0; |
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52 if (rng_nelem > 0) |
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53 { |
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54 if (rng_inc > 0) |
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55 retval = rng_base + (rng_nelem - 1) * rng_inc; |
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56 else |
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57 retval = rng_base; |
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58 } |
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59 return retval; |
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60 } |
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61 |
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62 void |
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63 Range::sort (void) |
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64 { |
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65 if (rng_base > rng_limit && rng_inc < 0.0) |
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66 { |
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67 double tmp = rng_base; |
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68 rng_base = min (); |
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69 rng_limit = tmp; |
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70 rng_inc = -rng_inc; |
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71 } |
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72 } |
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73 |
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74 void |
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75 Range::print_range (void) |
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76 { |
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208
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77 cerr << "Range: rng_base = " << rng_base |
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78 << " rng_limit " << rng_limit |
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79 << " rng_inc " << rng_inc |
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80 << " rng_nelem " << rng_nelem << "\n"; |
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81 } |
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82 |
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83 ostream& |
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84 operator << (ostream& os, const Range& a) |
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85 { |
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86 double b = a.base (); |
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87 double increment = a.inc (); |
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88 int num_elem = a.nelem (); |
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89 |
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90 for (int i = 0; i < num_elem; i++) |
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91 os << b + i * increment << " "; |
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92 |
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93 os << "\n"; |
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94 |
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95 return os; |
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96 } |
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97 |
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98 istream& |
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99 operator >> (istream& is, Range& a) |
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100 { |
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101 is >> a.rng_base; |
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102 if (is) |
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103 { |
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104 is >> a.rng_limit; |
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105 if (is) |
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106 { |
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208
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107 is >> a.rng_inc; |
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108 a.rng_nelem = a.nelem_internal (); |
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109 } |
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110 } |
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111 |
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112 return is; |
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113 } |
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114 |
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115 int |
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116 Range::nelem_internal (void) const |
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117 { |
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118 // Find an approximate number of elements, then do the best we can to |
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119 // find the number of elements that we would get if we had done |
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120 // something like |
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121 // |
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122 // nelem = 0; |
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123 // while (base + nelem * inc <= limit) |
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124 // nelem++; |
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125 // |
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126 // (for limit > base && inc > 0) |
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127 |
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128 double ntry = (rng_limit - rng_base) / rng_inc; |
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129 double max_val = (double) INT_MAX; |
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130 |
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131 if (ntry > max_val) |
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132 return -1; |
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133 |
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134 if (rng_limit > rng_base && rng_inc > 0) |
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135 { |
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136 // Our approximation may have been too big. |
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137 |
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138 while (rng_base + ntry * rng_inc > rng_limit && ntry > 0) |
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139 ntry = ntry - 1; |
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140 |
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141 // Now that we are close, get the actual number. |
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142 |
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143 while (rng_base + ntry * rng_inc <= rng_limit && ntry <= max_val) |
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144 ntry = ntry + 1; |
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145 } |
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146 else if (rng_limit < rng_base && rng_inc < 0) |
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147 { |
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148 // Our approximation may have been too big. |
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149 |
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150 while (rng_base + ntry * rng_inc < rng_limit && ntry > 0) |
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151 ntry = ntry - 1; |
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152 |
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153 // Now that we are close, get the actual number. |
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154 |
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155 while (rng_base + ntry * rng_inc >= rng_limit && ntry <= max_val) |
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156 ntry = ntry + 1; |
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157 } |
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158 else if (rng_limit == rng_base) |
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159 ntry = 1; |
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160 else |
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161 ntry = 0; |
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162 |
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163 if (ntry > max_val) |
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164 return -1; |
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165 else |
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166 return (int) ntry; |
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167 } |
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168 |
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169 /* |
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170 ;;; Local Variables: *** |
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171 ;;; mode: C++ *** |
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172 ;;; page-delimiter: "^/\\*" *** |
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173 ;;; End: *** |
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174 */ |
