Nonequispaced fast Fourier transform
Time and frequency nonequispaced
Nonequispaced fast Fourier transform 

NNFFT – Fourier transform with nonequispaced data in time and frequency domain

This library of C functions computes approximations of sums of the form \[ d_j := \sum\limits_{l=1}^{L-1} \alpha_l\, {\rm {e}}^{2\pi \mathrm{i} (k_l\odot N)x_j} \quad (j =1,\ldots,M) \] with \(k_l, x_j \in [-1/2,1/2)^d\) and \(\alpha_l \in \mathbb{C}\).

The algorithms are implemented by Tobias Knopp in ./examples/nnfft.

References

  • Keiner, J., Kunis, S., and Potts, D.
    Using NFFT 3 – a software library for various nonequispaced fast Fourier transforms.
    ACM Trans. Math. Software 36, Article 19, 1–30, 2009. pdf ps
  • Potts, D., Steidl, G., and Tasche, M.
    Fast Fourier transforms for nonequispaced data: A tutorial.
    In: Modern Sampling Theory: Mathematics and Applications, J. J. Benedetto and P. Ferreira (Eds.), Chapter 12, pages 249–274, 1998. pdf ps.Z