Fast Fourier Transform (FFT) on GPU with Nx?

thbar · February 2, 2025, 1:32pm

Hi!

Did anyone already implement FFT on Nx?

I came across various non-Nx solutions (including GitHub - brunosantanaa/fft: FFT - Fast Fourrier Transformer (Elixir Lang), stuff in Matrex etc).

Having implemented FFT in the past already, I could implement it myself on top of Nx but if someone already did the job somewhere, I am interested!

Thanks!

– Thibaut

thbar · February 2, 2025, 1:39pm

Aaaand… I found the perfect link right after posting. Here it is in case someone needs this:

With the neat companion Livebook:

github.com/elixir-nx/nx_signal

guides/fft.livemd

main

# The Discrete Fourier Transform (DFT)

```elixir
Mix.install([
  {:nx_signal, "~> 0.2"},
  {:vega_lite, "~> 0.1"},
  {:kino_vega_lite, "~> 0.1"}
])
```

## What is the Discrete Fourier Transform (DFT)?

This livebook will show you how to use the Discrete Fourier Transform (DFT) to analyze a signal.

Suppose we have a periodic signal which we want to analyze.

We will run a Fast Fourrier Transform, which is a fast algorithm to compute the DFT.
It transforms a time-domain function into the frequency domain.

<https://en.wikipedia.org/wiki/Discrete_Fourier_transform>

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Thanks @polvalente et al.!

– Thibaut