Module fft 

FFT wrapper for 3D transforms using rustfft

Provides 3D FFT/IFFT operations compatible with NumPy’s FFT conventions. Uses Fortran (column-major) order indexing to match NIfTI convention.

Structs

Fft3dWorkspace

FFT workspace that caches plans and scratch buffers for reuse

Fft3dWorkspaceF32

FFT workspace using f32 for better WASM performance Single precision halves memory bandwidth and is faster on most hardware

SendPtr 🔒

Wrapper to send a raw mutable pointer across threads. Stores as usize to avoid auto-trait issues with raw pointers. Safety: caller must guarantee non-overlapping access patterns.

Functions

fft3d

3D FFT (in-place, complex-to-complex)

fft3d_real

3D FFT of real data (real-to-complex)

fftfreq

Generate FFT frequency values for a given dimension Matches numpy.fft.fftfreq(n, d)

fftfreq_f32

Generate FFT frequency values (f32 version for WASM performance) Matches numpy.fft.fftfreq(n, d)

fftshift

3D FFT shift: swap quadrants so zero-frequency is at center

fftshift_inplace

3D FFT shift in-place: swap quadrants so zero-frequency is at center

idx3d

Index into a 3D array stored in Fortran order (column-major) index = x + ynx + znx*ny

ifft3d

3D IFFT (in-place, complex-to-complex)

ifft3d_real

3D IFFT returning real part (complex-to-real)

ifftshift

3D inverse FFT shift: undo fftshift

wrap_angle

Wrap angle to [-π, π]