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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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32 void |
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33 Range::print_range (void) |
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34 { |
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35 cerr << "Range: _base = " << _base |
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36 << " _limit " << _limit |
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37 << " _inc " << _inc |
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38 << " _nelem " << _nelem << "\n"; |
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39 } |
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40 |
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41 ostream& |
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42 operator << (ostream& os, const Range& a) |
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43 { |
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44 double b = a.base (); |
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45 double increment = a.inc (); |
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46 int num_elem = a.nelem (); |
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47 |
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48 for (int i = 0; i < num_elem; i++) |
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49 os << b + i * increment << " "; |
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50 |
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51 os << "\n"; |
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52 |
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53 return os; |
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54 } |
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55 |
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56 istream& |
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57 operator >> (istream& is, Range& a) |
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58 { |
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59 is >> a._base; |
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60 if (is) |
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61 { |
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62 is >> a._limit; |
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63 if (is) |
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64 { |
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65 is >> a._inc; |
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66 a._nelem = a.nelem_internal (); |
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67 } |
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68 } |
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69 |
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70 return is; |
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71 } |
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72 |
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73 int |
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74 Range::nelem_internal (void) const |
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75 { |
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76 // Find an approximate number of elements, then do the best we can to |
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77 // find the number of elements that we would get if we had done |
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78 // something like |
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79 // |
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80 // nelem = 0; |
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81 // while (base + nelem * inc <= limit) |
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82 // nelem++; |
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83 // |
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84 // (for limit > base && inc > 0) |
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85 |
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86 double ntry = (_limit - _base) / _inc; |
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87 double max_val = (double) INT_MAX; |
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88 |
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89 if (ntry > max_val) |
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90 return -1; |
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91 |
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92 if (_limit > _base && _inc > 0) |
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93 { |
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94 // Our approximation may have been too big. |
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95 |
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96 while (_base + ntry * _inc > _limit && ntry > 0) |
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97 ntry = ntry - 1; |
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98 |
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99 // Now that we are close, get the actual number. |
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100 |
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101 while (_base + ntry * _inc <= _limit && ntry <= max_val) |
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102 ntry = ntry + 1; |
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103 } |
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104 else if (_limit < _base && _inc < 0) |
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105 { |
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106 // Our approximation may have been too big. |
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107 |
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108 while (_base + ntry * _inc < _limit && ntry > 0) |
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109 ntry = ntry - 1; |
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110 |
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111 // Now that we are close, get the actual number. |
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112 |
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113 while (_base + ntry * _inc >= _limit && ntry <= max_val) |
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114 ntry = ntry + 1; |
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115 } |
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116 else if (_limit == _base) |
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117 ntry = 1; |
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118 else |
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119 ntry = 0; |
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120 |
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121 if (ntry > max_val) |
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122 return -1; |
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123 else |
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124 return (int) ntry; |
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125 } |
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126 |
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127 /* |
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128 ;;; Local Variables: *** |
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129 ;;; mode: C++ *** |
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130 ;;; page-delimiter: "^/\\*" *** |
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131 ;;; End: *** |
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132 */ |
