NDFT for nonequispaced data in time and frequency domain

the algorithms are written by Tobias Knopp 
based on the paper
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

Available from:
http://www.tu-chemnitz.de/~potts
 
