DFT.rb

# is a discrete fourier transform in ruby by corban http://en.wikipedia.org/wiki/Discrete_Fourier_transform

require 'complex'

TWO_PI = 2 * Math::PI

N = ARGV.first.to_i || 256

x = Array.new(N, rand)
X = Array.new(N, 0)

X.each_index do |k|
 x.each_index do |n|
   X[k] += x[n] * Math::E ** -((Complex(0, TWO_PI) / N) * k * n)
 end
end

gistfile2.txt

zetagun:~ corban$ time ruby DFT.rb 1024

real	1m4.676s
user	1m3.956s
sys	0m0.195s