Double-Batched FFT Library#

The Double-Batched FFT Library is a library for computing the Fast Fourier Transform (FFT). The library targets Graphics Processing Units, supporting OpenCL, Level Zero, and SYCL.

The library supports double-batching. That is, let $x$ be the input tensor of shape $M\times N_1\times \cdots \times N_D\times K$, with $D=1,2,3$. The D-dimensional FFT should be computed over the N-modes for every M-mode and K-mode. Think of a two-level nested loop over indices m and k where the FFT is applied on the subtensor $x(m,:,...,:,k)$. Double-batching means the capability to batch both indices m and k in a single kernel call. Note that most FFT library for GPUs support single-batching, e.g. for $M=1$.