fftpack51

fftpack51, a Fortran90 code which computes the Fast Fourier Transform, using double precision arithmetic, by Paul Swarztrauber and Dick Valent;

Special features include:

• real or complex data can be handled;
• separate routines for forward analysis (data => Fourier coefficients) and backward analysis (Fourier coefficients => data);
• sine and cosine transform routines;
• quarter wave sine and cosine transform routines;
• the amount of data is NOT required to be a power of 2.

Routines in the code come in groups of three:

• an initialization routine;
• the forward computational routine (data to FFT coefficients);
• the backward computational routine (FFT coefficients to data).

The following table shows how the names of the routines in each group:

Initialization	Forward	Backward	Purpose
CFFT1I	CFFT1F	CFFT1B	FFT for complex 1D data
CFFT2I	CFFT2F	CFFT2B	FFT for complex 2D data
CFFTMI	CFFTMF	CFFTMB	FFT for complex multi-D data
COSQ1I	COSQ1F	COSQ1B	Even function 1D quarter-cosine FFT
COSQMI	COSQMF	COSQMB	Even function 1D quarter-cosine FFT
COST1I	COST1F	COST1B	Even function 1D cosine FFT
COSTMI	COSTMF	COSTMB	Even function 1D cosine FFT
RFFT1I	RFFT1F	RFFT1B	FFT for real 1D data
RFFT2I	RFFT2F	RFFT2B	FFT for real 2D data
RFFTMI	RFFTMF	RFFTMB	FFT for real multi-D data
SINQ1I	SINQ1F	SINQ1B	Even function 1D quarter-sine FFT
SINQMI	SINQMF	SINQMB	Even function 1D quarter-sine FFT
SINT1I	SINT1F	SINT1B	Even function 1D sine FFT
SINTMI	SINTMF	SINTMB	Even function 1D sine FFT

Bugfixes from FFTPACK 5.0 to FFTPACK 5.1

The functionality of FFTPACK 5.1 is identical with the previous version 5.0.

The following bugfixes have been applied:

1. Corrected index error for high-level routines [CR]FFT[12][BFI] requiring WSAVE array, and all dependent routines to which LWSAVE is passed. Namely, in LWSAV = L + LOG(REAL(INT(L))) + 4 definitions, the summand term LOG(REAL(INT(L))) has been corrected to LOG(REAL(INT(L)/LOG(2.)).
2. Corrected index error in routime C1FM1F at label 56, where array offset was declared 1 that should have been 2. This resulted in C1FFTF transforms of length N calculated incorrectly, where N is any prime .GT. 5, or N=7*M, M .GE. 6.
3. Corrected RFFT2x routines by rewriting them. The backward transform followed by forward now returns identity. Input argument LENSAV must be be at least L + 3*M + INT(LOG(REAL(L))/LOG(2.)) + 2*INT(LOG(REAL(M))/LOG(2.)) +12. Previously, the required value was smaller.

Licensing:

Licensed under the GNU General Public License (GPL).
Copyright (C) 1995-2004, Scientific Computing Division,
University Corporation for Atmospheric Research.

Languages:

fftpack51 is available in a Fortran90 version.

Related codes:

fftpack5, a Fortran90 code which implements the Fast Fourier Transform.

fftpack51_test

fftw_test, Fortran90 codes which illustrate the use of the FFTW code for Fast Fourier Transforms, by Matteo Frigo and Steven Johnson.

sftpack, a Fortran90 code which implements the "slow" Fourier transform, intended as a teaching tool and comparison with the fast Fourier transform.

walsh_transform, a Fortran90 code which implements versions of the Walsh and Haar transforms.

xerror, a Fortran90 code which is used for error reporting.

Author:

The original Fortran77 version of this code was written by Dick Valent and Paul Swarztrauber, of the National Center for Atmospheric Research (NCAR).

Reference:

1. William Briggs, Van Emden Henson,
   The DFT: An Owner's Manual for the Discrete Fourier Transform,
   SIAM, 1995,
   ISBN13: 978-0-898713-42-8,
   LC: QA403.5.B75.
2. Elbert Brigham,
   The Fast Fourier Transform and Its Applications,
   Prentice-Hall, 1988,
   ISBN: 0133075052,
   LC: QA403.B74.
3. Bill Buzbee,
   The SLATEC Common Math code,
   in Sources and Development of Mathematical Software,
   edited by Wayne Cowell,
   Prentice-Hall, 1984,
   ISBN: 0-13-823501-5,
   LC: QA76.95.S68.
4. Eleanor Chu, Alan George,
   Inside the FFT Black Box,
   CRC Press,
   ISBN: 0849302706,
   LC: QA403.5C5.
5. David Kahaner, Cleve Moler, Steven Nash,
   Numerical Methods and Software,
   Prentice Hall, 1989,
   ISBN: 0-13-627258-4,
   LC: TA345.K34.
6. Paul Swarztrauber,
   Symmetric FFT's,
   Mathematics of Computation,
   Volume 47, Number 175, July 1986, pages 323-346.
7. Paul Swarztrauber,
   Vectorizing the Fast Fourier Transforms,
   in Parallel Computations,
   edited by Garry Rodrigue,
   Academic Press, 1982,
   ISBN: 0125921012,
   LC: QA76.6.P348.
8. Paul Swarztrauber,
   Fast Fourier Transform Algorithms for Vector Computers,
   Parallel Computing,
   Volume 1, Number 1, August 1984, pages 45-63.

Source Code:

• fftpack51.f90, the source code.
• fftpack51.sh, compiles the source code.