Crate ndrustfft

Expand description

ndrustfft: n-dimensional complex-to-complex FFT, real-to-complex FFT and real-to-real DCT

This library is a wrapper for RustFFT, RustDCT and RealFft that enables performing FFTs and DCTs of complex- and real-valued data on n-dimensional arrays (ndarray).

ndrustfft provides Handler structs for FFT’s and DCTs, which must be provided alongside with the arrays to the respective functions (see below) . The Handlers implement a process function, which is a wrapper around Rustfft’s process. Transforms along the outermost axis are in general the fastest, while transforms along other axis’ will temporarily create copies of the input array.

fft : ndfft, ndfft_par
ifft: ndifft,ndifft_par

Real-to-complex

fft_r2c : ndfft_r2c, ndfft_r2c_par,

Complex-to-real

ifft_r2c: ndifft_r2c,ndifft_r2c_par

Real-to-real

Example

2-Dimensional real-to-complex fft along first axis

use ndarray::{Array2, Dim, Ix};
use ndrustfft::{ndfft_r2c, Complex, R2cFftHandler};

let (nx, ny) = (6, 4);
let mut data = Array2::<f64>::zeros((nx, ny));
let mut vhat = Array2::<Complex<f64>>::zeros((nx / 2 + 1, ny));
for (i, v) in data.iter_mut().enumerate() {
    *v = i as f64;
}
let mut fft_handler = R2cFftHandler::<f64>::new(nx);
ndfft_r2c(
    &data.view(),
    &mut vhat.view_mut(),
    &mut fft_handler,
    0,
);

Versions

v0.3.0: Upgrade RealFft to 3.0.0 and RustDCT to 0.7
>= v0.2.2:

The first and last elements of real-to-complex transforms are per definition purely real. This is now enforced actively, by setting the complex part to zero - similar to numpys rfft.