gistfile1.rb

require 'benchmark'
a = Array.new(4096) { [rand(1 << 64), rand(1 << 64)] }
n = 1 << 32
Benchmark.bmbm do |x|
  x.report do
    a.collect do |b|
      a.select do |c|
        n >= Math.sqrt(
          (b[0] - c[0]) ** 2 + (b[1] - c[1]) ** 2
        )
      end
    end
  end
end

ruby 1.8.7 (2012-04-14 patchlevel 361) [x86_64-linux]

Rehearsal ------------------------------------
  88.860000   3.410000  92.270000 ( 92.315821)
-------------------------- total: 92.270000sec

       user     system      total        real
  85.220000   3.690000  88.910000 ( 88.928956)

ruby 2.0.0dev (2012-04-16 trunk 35345) [x86_64-linux]

Rehearsal ------------------------------------
 122.530000   0.340000 122.870000 (122.910743)
------------------------- total: 122.870000sec

       user     system      total        real
 119.470000   0.050000 119.520000 (119.579139)