This program calculates the fast fourier transform of very long series, as long as your far heap allows. For example, using double precision it is posible to process 70.000 real data points. It implements r. C. Singleton's mixed radix fast fourier algorithm. Some features of this algorithm are: 1) the length of the series does not have to be be necessarily a power of two, the length may include factors of 2 and 4, and also odd factors as 3,5,7, etc,2-) to avoid truncation errors, the sines and cosines are generated recursively, 3-) the data and its trtransform are accessed with huge pointers.

The source code is written in C.

Look at the readme file from the program.