GPFA

GPFA is a library purchased from the European Centre for Medium-Range Weather Forcasting (ECMWF), for computing the fast Fourier transform of complex periodic sequences. Its primary user entries SETGPFA and GPFA are Fortran-callable. Routine SETGPFA is a setup routine, and routine GPFA is referred to as a "multiple transform" because it transforms multiple sequences within a single array, and the operative vector length is the number of sequences transformed by a given call.

Recommendation: Use routine GPFA if your application calls it and it is available on your target SCD computer. Otherwise, check the computer vendor's performance library for a suitable replacement routine. If you intend to run your application on a Cray parallel-vector computer at a site which has not purchased routine GPFA from ECMWF, use routines CFTFAX and CFFTMLT from Cray library SCI to replace routines SETGPFA and GPFA, respectively.

Documentation: please see the README file in SCD's gpfa source directory for a library overview plus usage instructions for each of GPFA's user entries.
Source code: The official GPFA source code is not available from NCAR, but you may purchase it from ECMWF.
NCAR users: the GPFA binary library is available to NCAR computer users, for linking and running with Fortran programs, on some of SCD's compute-servers. See table SCD Computers, Products, and Libraries" for the names of those computers. If you have questions about linking the binary library on these NCAR systems, please see "Linking SCD's Local Fortran Math Libraries".

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