# File lib/lolcat/lol.rb, line 35
  def self.rainbow(freq, i)
     red   = Math.sin(freq*i + 0) * 127 + 128
     green = Math.sin(freq*i + 2*Math::PI/3) * 127 + 128
     blue  = Math.sin(freq*i + 4*Math::PI/3) * 127 + 128
     "#%02X%02X%02X" % [ red, green, blue ]
  end