sqrt by newton method

newton.rb

# coding: utf-8

#
# sqrt by newton method
#

def gen_sqrt_iter(square, seed=1)
  Fiber.new do
    f  = ->(x){ x**2.0 - square }
    fd = ->(x){ 2.0 * x }
    xn = ->(x){ x - f[x]/fd[x] }

    x = seed
    loop do
      Fiber.yield(x = xn[x])
    end
  end
end

# main: sqrt of 2
iter = gen_sqrt_iter(2)
10.times do
  puts iter.resume
end