source: lmdz_wrf/WRFV3/external/fftpack/README @ 1

Web site for convert.f90:
ftp://ftp.numerical.rl.ac.uk/pub/MandR/convert.f90

!     Copyright CERN, Geneva 1991, 1997 - Copyright and any other
!     appropriate legal protection of these computer programs
!     and associated documentation reserved in all countries
!     of the world.
!     Author: Michael Metcalf  (MichaelMetcalf@compuserve.com)

======================================================

Web site for fftpack5:
http://www.cisl.ucar.edu/css/software/fftpack5/

FFTPACK is a Fortran subroutine library of Fast Fourier Transforms (FFT's) 
developed at the National Center for Atmospheric Research. Version 5 of the 
library was written by Paul Swarztrauber and Richard Valent in the mid 
1990's. This release of FFTPACK includes single and multiple instance 
complex-to-complex and real-to-real transforms, two-dimensional complex-
to-complex and real-to-complex transforms, and a collection of sine and 
cosine transforms.  

References

(1) Vectorizing the Fast Fourier Transforms, by Paul Swarztrauber, 
    Parallel Computations, G. Rodrigue, ed., Academic Press, New York 1982.

(2) Fast Fourier Transforms Algorithms for Vector Computers, by Paul 
    Swarztrauber, Parallel Computing, (1984) pp.45-63.

(3) Symmetric FFTs, by P. N. Swarztrauber, Mathematics of Computation 47(1986), 
    pp. 323-346.

==========

The WRF usage of the fftpack5 package is for filtering high-latitude
data for usage in the global implementation.  The files have been 
moved from little .f files to big .F files (to adopt the WRF convention).
Additionally, the Makefile has been modified to accomodate this small
naming change for the default suffix.  

The fftpack source has been changed by the convert.f90 program, turning
the code into free-format.  The only other modification is that the
imbedded tabs in the source have been turned into spaces (otherwise
convert.f90 coughs up a spleen).