Dataflow Diagram or Pseudo Code for Fast Fourier Transform?

I have an ArrayList that has Double elements. I want to implement FFT(Fast Fourier Trans开发者_Go百科form) on it. However I don't want to take a Java code somewhere else and copy it. How can I find the understandable dataflow diagram or pseudo code of FFT algorithm?

PS: My ArrayList variable is a one-dimensional List.

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Would diagram in this article satisfy you: http://en.wikipedia.org/wiki/Cooley%E2%80%93Tukey_FFT_algorithm ?

I built a Pascal program that was using this method almost 20 years ago.