Pipelined phase-rotation FFT
- By David O'Halloran. The Welchel phase-rotation FFT is a new form of the fast Fourier transform (FFT) that replaces data movement at runtime with equivalent multiplications by precomputed constants. The result is an FFT that is easy to pipeline.
- http://www.cs.cmu.edu/afs/cs.cmu.edu/project/iwarp/member/fx/public/www/phase1.html

FFTPK90
- Translation of fftpack and vfftpk to Fortran 95 by Simon Clarke.
- http://www.maths.monash.edu.au/~src/fftpk90

CHIRP-Z transform for FFTs
- Little known algorithm for calculating the FFT of a series of any length. Based upon Applied Statistics algorithms 117 & 83.
- http://users.bigpond.net.au/amiller/apstat/chirp.f90

Jörgs Useful and Ugly FFT page
- Code and links in Fortran and C for the Fast Fourier Transform.
- http://www.jjj.de/fft/fftpage.html

Fast Fourier Transform code
- By James Van Buskirk.
- http://home.comcast.net/~kmbtib/index.html

Ernst Mayer
- Fortran 90 codes for Fast Fourier Transforms and Discrete Weighted Transforms, for use in number theory research.
- http://hogranch.com/mayer/resume.html