1 | class Rational < Numeric
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2 | def inspect
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3 | "(#{to_s})"
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4 | end
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5 |
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6 | def to_s
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7 | "#{numerator}/#{denominator}"
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8 | end
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9 |
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10 | def *(rhs)
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11 | if rhs.is_a? Rational
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12 | Rational(numerator * rhs.numerator, denominator * rhs.denominator)
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13 | elsif rhs.is_a? Integer
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14 | Rational(numerator * rhs, denominator)
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15 | elsif rhs.is_a? Numeric
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16 | numerator * rhs / denominator
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17 | end
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18 | end
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19 |
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20 | def +(rhs)
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21 | if rhs.is_a? Rational
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22 | Rational(numerator * rhs.denominator + rhs.numerator * denominator, denominator * rhs.denominator)
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23 | elsif rhs.is_a? Integer
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24 | Rational(numerator + rhs * denominator, denominator)
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25 | elsif rhs.is_a? Numeric
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26 | (numerator + rhs * denominator) / denominator
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27 | end
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28 | end
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29 |
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30 | def -(rhs)
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31 | if rhs.is_a? Rational
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32 | Rational(numerator * rhs.denominator - rhs.numerator * denominator, denominator * rhs.denominator)
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33 | elsif rhs.is_a? Integer
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34 | Rational(numerator - rhs * denominator, denominator)
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35 | elsif rhs.is_a? Numeric
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36 | (numerator - rhs * denominator) / denominator
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37 | end
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38 | end
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39 |
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40 | def /(rhs)
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41 | if rhs.is_a? Rational
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42 | Rational(numerator * rhs.denominator, denominator * rhs.numerator)
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43 | elsif rhs.is_a? Integer
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44 | Rational(numerator, denominator * rhs)
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45 | elsif rhs.is_a? Numeric
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46 | numerator / rhs / denominator
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47 | end
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48 | end
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49 |
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50 | def <=>(rhs)
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51 | if rhs.is_a?(Integral)
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52 | return numerator <=> rhs if denominator == 1
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53 | rhs = Rational(rhs)
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54 | end
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55 |
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56 | case rhs
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57 | when Rational
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58 | (numerator * rhs.denominator - denominator * rhs.numerator) <=> 0
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59 | when Numeric
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60 | (rhs <=> self)&.-@
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61 | else
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62 | nil
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63 | end
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64 | end
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65 |
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66 | def ==(rhs)
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67 | return true if self.equal?(rhs)
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68 | if rhs.is_a?(Integral) && denominator == 1
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69 | return numerator == rhs
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70 | end
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71 | if rhs.is_a?(Rational)
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72 | numerator * rhs.denominator == denominator * rhs.numerator
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73 | else
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74 | rhs == self
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75 | end
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76 | end
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77 | end
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78 |
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79 | class Numeric
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80 | def to_r
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81 | Rational(self, 1)
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82 | end
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83 | end
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84 |
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85 | module Kernel
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86 | def Rational(numerator, denominator = 1)
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87 | a = numerator
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88 | b = denominator
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89 | a, b = b, a % b until b == 0
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90 | Rational._new(numerator.div(a), denominator.div(a))
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91 | end
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92 |
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93 | [:+, :-, :*, :/, :<=>, :==, :<, :<=, :>, :>=].each do |op|
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94 | Fixnum.instance_eval do
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95 | original_operator_name = "__original_operator_#{op}_rational"
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96 | alias_method original_operator_name, op
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97 | define_method op do |rhs|
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98 | if rhs.is_a? Rational
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99 | Rational(self).__send__(op, rhs)
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100 | else
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101 | __send__(original_operator_name, rhs)
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102 | end
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103 | end
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104 | end
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105 | Float.instance_eval do
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106 | original_operator_name = "__original_operator_#{op}_rational"
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107 | alias_method original_operator_name, op
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108 | define_method op do |rhs|
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109 | if rhs.is_a? Rational
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110 | rhs = rhs.to_f
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111 | end
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112 | __send__(original_operator_name, rhs)
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113 | end
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114 | end if Object.const_defined?(:Float)
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115 | end
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116 | end
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117 |
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