cfrac.rb

class Float
    def decimal
        self % 1.0   # extract decimal part
    end
end

module Enumerable
    def scan c,&block
        s = [c]
        self.each {|v|
            s << (c = block.call(v,c))
        }
        s
    end
end

class ContFraction < Array
    def initialize(t=0.0, eps = 0.0001)
        if t.class == Float then
            push t.to_i
            while t.decimal.abs > eps
                t = 1.0/t.decimal
                push t.to_i
            end
        else 
            super(t)
        end
    end

    def indent lines
        @len = lines.map(&:length)
        p = @len.scan(0) {|i,curpos| curpos + (i + 3)}
        p[p.length-1] -= 4
        @pos = p.clone
        lines.each {|line| line.prepend " "*p.shift}
        lines
    end

    def decorate lines
        lftmst = @pos.pop - 3
        (lines.length-2).downto(0){ |i|
            l = lftmst - @pos[i] +1 - @len[i]
            lines[i] += " + " + "-" * l
            lines.insert(i, " " * (@len[i]+@pos[i]+3) + "1".center(l))
        }
        lines
    end

    def inspect
        lines = self.map(&:to_s)
        lines = indent lines
        lines = decorate lines
        lines.join "\n"
    end

    def to_r
        seq = self.to_a
        ans = Rational(seq.pop)
        while not seq.empty?
            ans = seq.pop + 1/ans 
        end
        ans
    end
end

if $0 == __FILE__ then
    t = ContFraction.new ARGV.pop.to_f
    p t
    puts "a = #{t.to_r}"
end