12/06/2011
Authors: Paul N. Swarztrauber and Richard A. Valent
FFTPACK5.1 is written in Fortran77 but it does not comply strictly with the Fortran standard. We have not compiled a list of FFTPACK Fortran standards violations. Users whose projects require strict adherence to the standard should not use this package.
Documentation is provided in HTML format in file FFTPACK5.1.html. Information about building the library follows below, as well as a synopsis of the library.
The functionality of FFTPACK 5.1 is identical with the previous version 5.0. The following bugfixes have been applied:
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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.)).
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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.
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Corrected RFFT2x routines by rewriting them. The backward transform followed by forward now returns identity. Input argument LENSAV must be be at least L + 3M + INT(LOG(REAL(L))/LOG(2.)) + 2INT(LOG(REAL(M))/LOG(2.)) +12. Previously, the required value was smaller.
It is best to make the library and test executables with a Fortran 90 compiler. The test programs use Fortran 90 intrnisics random_seed and random_number.
The included Makefile is configured to build a static library on many currently available unix and unix-like operating systems having a commonly available Fortran compiler.
Examine file make.inc to see if your OS and compiler are represented.
If they are not, you should modify file make.inc and the Makefile in
each directory (main, src and test) according to your needs.
The source code is by default configured for single precision real numbers. If double precision is desired, Makefile and make.inc must be modified with the appropriate compiler options for promoting real to double precision as well as promoting constants to double precision (this is often "-r8" on some, but not all, compilers).