/tools/Ruby/lib/ruby/1.8/bigdecimal/util.rb

 1#
 2# BigDecimal utility library.
 3#
 4# To use these functions, require 'bigdecimal/util'
 5#
 6# The following methods are provided to convert other types to BigDecimals:
 7#
 8#   String#to_d -> BigDecimal
 9#   Float#to_d -> BigDecimal
10#   Rational#to_d -> BigDecimal
11#
12# The following method is provided to convert BigDecimals to other types:
13#
14#   BigDecimal#to_r -> Rational
15#
16# ----------------------------------------------------------------------
17#
18class Float < Numeric
19  def to_d
20    BigDecimal(self.to_s)
21  end
22end
23
24class String
25  def to_d
26    BigDecimal(self)
27  end
28end
29
30class BigDecimal < Numeric
31  # Converts a BigDecimal to a String of the form "nnnnnn.mmm".
32  # This method is deprecated; use BigDecimal#to_s("F") instead.
33  def to_digits
34     if self.nan? || self.infinite? || self.zero?
35        self.to_s
36     else
37       i       = self.to_i.to_s
38       s,f,y,z = self.frac.split
39       i + "." + ("0"*(-z)) + f
40     end
41  end
42
43  # Converts a BigDecimal to a Rational.
44  def to_r 
45     sign,digits,base,power = self.split
46     numerator = sign*digits.to_i
47     denomi_power = power - digits.size # base is always 10
48     if denomi_power < 0
49        Rational(numerator,base ** (-denomi_power))
50     else
51        Rational(numerator * (base ** denomi_power),1)
52     end
53  end
54end
55
56class Rational < Numeric
57  # Converts a Rational to a BigDecimal
58  def to_d(nFig=0)
59     num = self.numerator.to_s
60     if nFig<=0
61        nFig = BigDecimal.double_fig*2+1
62     end
63     BigDecimal.new(num).div(self.denominator,nFig)
64  end
65end