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module Stellar
module Util
class ContinuedFraction
MAX_PRECISION = (2**32) - 1
attr_reader :i
attr_reader :f
def self.best_r(number, max_precision=MAX_PRECISION)
cur_cf = new(number)
loop do
next_cf = cur_cf.extend()
cur_r = cur_cf.to_r(max_precision)
next_r = next_cf.to_r(max_precision)
break cur_r if cur_cf.done? || cur_r == next_r
cur_cf = next_cf
end
cur_cf.to_r(max_precision)
end
def initialize(val, parents=[])
@i = val.floor
@f = val - @i
@parents = parents
end
def to_a
@parents + [i]
end
def error(actual)
(actual - to_f).abs
end
def to_f
convergent = convergents.last
convergent.n / convergent.d.to_f
end
def convergents
return @convergents if defined? @convergents
c = [Fraction.new(0,1), Fraction.new(1,0)]
to_a.each_with_index do |a, i|
i = i + 2
h = a * c[i-1].n + c[i-2].n
k = a * c[i-1].d + c[i-2].d
c << Fraction.new(h,k)
end
@converegents = c[2..-1]
end
def to_r(max_precision=MAX_PRECISION)
fraction = convergents.take_while do |c|
c.n <= max_precision && c.d <= max_precision
end.last
Rational(fraction.n, fraction.d)
end
def done?
@f == 0
end
def extend(count=1)
result = self
count.times do
break if result.done?
result = ContinuedFraction.new(1 / result.f, result.to_a)
end
result
end
class Fraction
attr_reader :n
attr_reader :d
def initialize(n,d)
@n = n
@d = d
end
def to_r
Rational(@n, @d)
end
end
end
end
end
Version data entries
49 entries across 49 versions & 3 rubygems