C_FFT.C

This function is based on a paper entitled "A New Principle for Fast Fourier Transformation", Charles M. Rader and N.M. Brenner, I.E.E.E. Transactions on Acoustics, Speech and Signal Processing, June 1976, pp 264-266.  It is loosely based on a translation of a FORTRAN subroutine "FOUREA", which appeared in the book "Programs for Digital Signal Processing", published by I.E.E.E. Press, chapter 1, section 1.1, 1979.
