inverse FFT in shader language?

Question

does anyone know an implementation of the inverse FFT in HLSL/GLSL/cg ... ?

It would save me much work.

Best, heinrich

Answer 1

Do you already have a FFT implementation? You may already be aware, but the inverse can be computed by reversing the order of the N inputs, taking the FFT over those, and dividing the result by N.

Answer 2

DirectX11 comes with a FFT example for compute shaders (see DX11 August SDK Release Notes). As PereAllenWebb points out, this can be also used for inverse FFT.

Edit: If you just want a fast FFT, you could try the CUFFT, which runs on the GPU. It's part of the CUDA SDK. The AMCL from AMD also has a FFT, which is currently not GPU accelerated, but this will be likely added soon.