FFT Butterfly Diagram Screensaver
The FFT Butterfly Diagram screensaver runs a real Fast Fourier Transform live, computing a random signal's frequency components through its actual butterfly network. It is free, runs in your browser, and ESC exits.
How the FFT Butterfly Diagram screensaver works
The saver generates a real random signal, then runs a genuine radix-2 Fast Fourier Transform on it stage by stage.
Each stage draws the real butterfly connections — pairs of values combined by addition and subtraction with a twiddle factor — exactly as a real FFT computes.
The signal's real frequency spectrum builds up progressively as each butterfly stage completes, shown lighting up in sequence.
Once the full transform completes, the resulting real spectrum holds briefly, then a fresh random signal and transform begin.
A worked example
A signal built from two real, clean sine waves resolves into just two sharp spikes in the final frequency spectrum, exactly where the real FFT places their true frequencies.
Settings & tips
- Accent recolours the active butterfly stage.
- This is a real, correct radix-2 FFT implementation.
- A fresh random signal generates automatically once the transform completes.
Frequently asked questions
- Is this a real FFT?
- Yes — a real, correct radix-2 Fast Fourier Transform, with every butterfly stage shown as it actually computes.
- What is a "butterfly"?
- The real, named pattern of one add-and-subtract pair in the FFT's computation graph — it visually resembles butterfly wings.
- Is a key needed?
- No — it is a pure local computation.
- Is it free?
- Yes — free, no download, in your browser.