JTransforms is the first, open source, multithreaded FFT library written
in pure Java. Currently, four types of transforms are available:
Discrete Fourier Transform (DFT), Discrete Cosine Transform (DCT),
Discrete Sine Transform (DST) and Discrete Hartley Transform (DHT).
The code is derived from General Purpose FFT Package written by
Takuya Ooura and from Java FFTPack written by Baoshe Zhang. This
version has been modified to daemonize threads and stop any application
using the library waiting after execution has finished, and is based on
revision 29 of the svn version of the code from 2014-05-18.