news

FFTW, a collection of fast C routines to compute the Discrete Fourier Transform in one or more dime

Version 2.1.5 (3/24/2003)

  * Bug fix: Fortran wrappers were disabled in version 2.1.4.

Version 2.1.4 (3/16/2003)

  * Upgraded to newer versions of autoconf, etcetera, to fix compilation
    problems on various recent systems.

  * The configure script no longer picks the wrong architecture flags
    (which caused FFTW to crash) on newer IBM POWER machines running AIX.

  * Multi-threaded transforms should now utilize multiple CPUs on
    Solaris (which creates threads in single-processor mode by default).

  * Added experimental support for OpenMP (and SGI MP) compiler
    parallelization directives in the multi-threaded transforms,
    instead of using explicit thread spawning.  Enable by configuring
    --with-openmp or --with-sgi-mp in addition to --enable-threads.

  * Expanded FAQ.

Version 2.1.3 (11/7/1999)

  * The configure script no longer overrides the CFLAGS environment
    variable if it is defined.  (Thanks to Diab Jerius.)

  * Experimental Fortran-callable wrapper routines for MPI FFTW.
    See mpi/README.f77 for more information.

  * The configure script now detects and works around a stack
    alignment bug in gcc 2.95.x on x86.

  * configure attempts to guess the appropriate -mcpu flag on 
    Linux/PPC systems, improving performance (especially on G3s with
    gcc 2.95 or later).

  * Fixed integer overflow bug for complex transforms of large prime
    sizes (> 32768).  Thanks to Ezio Riva for the bug report.

  * Fixed memory leak in the Matlab wrappers; thanks to Matthew Davis
    for the bug report.

  * Fixed bugs in the configure script when detecting POSIX threads
    libraries on AIX and Tru64 (nee Digital) Unix.

  * Fixed bug in multi-threaded transforms on AIX (which strangely
    creates threads in non-joinable mode by default).  Thanks to
    Jim Lindsay for the bug report, and for allowing us to debug on
    Northwestern University's IBM SP2.

  * Slight fix to help build DLL's on Win32 (thanks to Andrew Sterian).

Version 2.1.2 (5/18/1999)

  * Fixed bug in our MPI test programs which made them fail under MPICH with
    the p4 device (TCP/IP).  (The 2.1.1 transforms worked, but the test
    programs crashed.)

  * Added missing fftw_f77_threads_init function to the Fortran wrappers
    for the multi-threaded transforms.  Thanks to V. Sundararajan for
    the bug report.

  * The codelet generator can now output efficient hard-coded DCT/DST
    transforms.  As a side effect of this work, we slightly reduced the 
    code size of rfftw.

  * Test programs now support GNU-style long options when used with glibc.

  * Added some more ideas to our TODO list.

  * Improved codelet generator speed.

Version 2.1.1 (3/31/1999)

  * Fixed bug in the complex transforms for certain sizes with
    intermediate-length prime factors (17-97), which under some 
    (hopefully rare) circumstances could cause incorrect results.
    Thanks to Ming-Chang Liu for the bug report and patch.  (The test
    program will now catch this sort of problem when it is run in
    paranoid mode.)

Version 2.1 (3/8/1999)

  * Added Fortran-callable wrapper routines for the multi-threaded
    transforms.

  * Documentation fixes and improvements.

  * The --enable-type-prefix option to configure makes it easy to install
    both single- and double-precision versions of FFTW on the same
    (Unix) system.  (See the installation section of the manual.)

  * The MPI FFTW routines now include parallel one-dimensional transforms
    for complex data.  (See the fftw_mpi documentation in the FFTW
    manual.)

  * The MPI FFTW routines now include parallel multi-dimensional transforms
    specialized for real data.  (See the rfftwnd_mpi documentation in the
    FFTW manual.)

  * The MPI FFTW routines are now documented in the main
    manual (in the doc directory).  On Unix systems, they are also
    automatically configured, compiled, and installed along with the main
    FFTW library when you include --enable-mpi in the flags to the
    configure script.  (See the FFTW manual.)

  * Largely-rewritten MPI code.  It is now cleaner and (sometimes) faster.
    It also supports the option of a user-supplied workspace for (often)
    greater performance (using the MPI_Alltoall primitive).  Beware that
    the interfaces have changed slightly, however.

  * The multi-threaded FFTW routines now include parallel one- and
    multi-dimensional transforms of real data.  (See the rfftw_threads
    documentation in the FFTW manual.)

  * The multi-threaded FFTW routines are now documented in the main
    manual (in the doc directory).  On Unix systems, they are also
    automatically configured, compiled, and installed along with the main
    FFTW library when you include --enable-threads in the flags to the
    configure script.  (See the FFTW manual.)

  * The multi-threaded FFTW routines now include support for Mach C 
    threads (used, for example, in Apple's MacOS X).

  * The Fortran-callable wrapper routines are now incorporated into
    the ordinary FFTW libraries by default (although you can
    disable this with the --disable-fortran option to configure) and
    are documented in the main FFTW manual.

  * Added an illustration of the data layout to the rfftwnd tutorial
    section of the manual, in the hope of preventing future confusion
    on this subject.

  * The test programs now allow you to specify multidimensional sizes
    (e.g. 128x54x81) for the -c and -s correctness and speed test options.

Version 2.0.1 (9/29/98)

  * (bug fix) Due to a poorly-parenthesized expression, rfftwnd overflowed
    32-bit integer precision for rank > 1 transforms with a final
    dimension >= 65536.  This is now fixed.  (Thanks to Walter Brisken
    for the bug report.)

  * (bug fix) Added definition of FFTW_OUT_OF_PLACE to fftw.h.  The
    flag is mentioned several times in the documentation, but its
    definition was accidentally omitted since FFTW_OUT_OF_PLACE is the
    default behavior.

  * Corrected various small errors in the documentation.  Thanks to
    Geir Thomassen and Jeremy Buhler for their comments.

  * Improved speed of the codelet generator by orders of magnitude,
    since a user needed a hard-coded fft of size 101.

  * Modified buffering in multidimensional transforms for some speed
    improvements (only when fftwnd_create_plan_specific is used).
    Thanks to Geert van Kempen for his tips.

  * Added Andrew Sterian's patch to allow FFTW to be used as a shared
    library more easily on Win32.

Version 2.0 (9/11/1998)

  * Completely rewritten real-complex transforms, now using
    specialized codelets and an inherently real-complex algorithm for
    greatly increased speed.  Also, rfftw can now handle odd sizes and
    strided transforms.  Beware that the output format for 1D rfftw
    transforms has changed.  See the manual for more details.

  * The complex transforms now use a fast algorithm for large prime
    factors, working in O(N lg N) time even for prime sizes.
    (Previously, the complexity contained an O(p^2) term, where p is
    the largest prime factor of N.  This is still the case for the
    rfftw transforms.)  Small prime factors are still more efficient,
    however.

  * Added functions fftw_one, fftwnd_one, rfftw_one, etcetera, to
    simplify and clarify the use of fftw for single, unit-stride
    transforms.

  * Renamed FFTW_COMPLEX, FFTW_REAL to fftw_complex, fftw_real (for
    greater consistency in capitalization).  The all-caps names will
    continue to be supported indefinitely, but are deprecated.  (Also,
    support for the COMPLEX and REAL types from FFTW 1.0 is now
    disabled by default.)

  * There are now Fortran-callable wrappers for the rfftw real-complex
    transforms.

  * New section of the manual discussing the use of FFTW with multiple
    threads, and a new FFTW_THREADSAFE flag (described therein).

  * Added shared library support.  Use configure --enable-shared to
    produce a shared library instead of a static library (the default).

  * Dropped support for the operation-count (*_op_count) routines
    introduced in v1.3, as these were little-used and were a pain to
    keep up-to-date as FFTW changed internally.

  * Made it easier to support floating-point types other than float
    and double (e.g. long double).  (See the file fftw-int.h.)

Version 1.3 (4/9/1998)

  * Multi-dimensional transforms contain significant performance
    improvements for dimensions >= 3.

  * Performance improvements in multi-dimensional transforms
    with howmany > 1 and stride > dist.

  * Improved parallelization and performance in the threads
    code for dimensions >= 3.

  * Changed the wisdom import/export format (the new wisdom remembers
    the stride of the plan that generated it, for use with the new
    create_plan_specific functions).  (You should regenerate any stored
    wisdom you have anyway, since this is a new version of FFTW.)

  * Several small fixes to aid compilation on some systems.

  * Fixed a bug in the MPI transform (in the transpose routine) that
    caused errors for some array sizes.

  * Fixed the (hopefully) last few things causing problems with C++
    compilers.

  * Hack for x86/gcc to properly align local double-precision variables.

  * Completely rewritten codelet generator.  Now it produces
    better code for non powers of 2, and is ready to produce
    real->complex transforms.

  * Testing algorithm is now more robust, and has a more rigorous
    theoretical foundation.  (Bugs in testing large transforms or
    in single precision are now fixed--these bugs were only in the
    test programs and not in the FFTW library itself.)

  * Added "specific" planners, which allow plan optimization for a
    specific array/stride.  They also reduce the memory requirements
    of the planner, and permit new optimizations in the multi-dimensional
    case.  (See the *_create_plan_specific functions.)

  * FFTW can now compute a count of the number of arithmetic operations
    it requires, which is useful for some academic purposes.  (See the
    *_count_plan_ops functions.)

  * Adapted for use with GNU autoconf to aid installation on UNIX systems.
    (Installation on non-UNIX systems should be the same as before.)

  * Used gettimeofday function if available.  (This function typically
    has much higher accuracy than clock(), permitting plans to be
    created much more quickly than before on many machines.)

  * Made timing algorithm (hopefully) more robust in the face of
    system interrupts, etc.

  * Added wrapper routines for calling FFTW from MATLAB (in the
    matlab/ directory).

  * Added wrapper routines for calling FFTW from Fortran (in the
    fortran/ directory).  (These were available separately before.)

Version 1.2.1 (12/4/1997)

  * Fixed a third bug in the mpi transpose routines (sheesh!) that
    could cause problems when re-using a transpose plan.  Thanks
    to Eric Skyllingstad for the bug reports.

  * Fixed another bug in the mpi transpose routines. This bug produced
    a memory leak and also occasionally tries to free a null pointer,
    which causes problems on some systems.  The mpi transpose/fft routines
    now pass all of our malloc paranoia tests.

  * Fixed bug in mpi transpose routines, where wrong results 
    could be given for some large 2D arrays.

Version 1.2 (9/8/1997)

  * Added a FAQ (in the FAQ/ directory).

  * Fixed bug in rfftwnd routines where a block was accidentally
    allocated to be too small, causing random memory to be
    overwritten (yikes!).  (Amazingly, this bug only caused the
    test program to fail on one system that we could find.  Our
    test suite can now catch this sort of bug.)

  * Abstractified taking differences of times (with fftw_time_diff
    macro/function) to allow more general timer data structures.

  * Added "wisdom" mechanism for saving plans & related info.

  * Made timing mechanism more robust and maintainable.  (Instead of
    using a fixed number of iterations, we now repeatedly double
    the number of iterations until a specified time interval
    (FFTW_TIME_MIN) is reached.)

  * Fixed header files to prevent difficulties when a mix of C and
    C++ compilers is used, and to prevent problems with multiple
    inclusions.

  * Added experimental distributed-memory transforms using MPI.

  * Fixed memory leak in fftwnd_destroy_plan (reported by Richard
    Sullivan).  Our test programs now all check for leaks.

Version 1.1 (5/5/1997)

  * Improved speed (yes!) [Some clever tricks with twiddle factors
    and better code generator]

  * Renamed `blocks' to `codelets', just to be fashionable

  * Rewritten planner and executor--much simpler and more readable
    code.  Reference-counter garbage collection employed throughout.

  * Much improved codelet generator.  The ML code should be now
    readable by humans, and easier to modify.

  * Support for Prime Factor transforms in the codelet generator.

  * Renamed COMPLEX -> FFTW_COMPLEX to avoid clashes with
    existing packages.  COMPLEX is still supported
    for compatibility with 1.0

  * Added experimental real->complex transform (quick hack,
    use at your own risk).

  * Added experimental parallel transforms using Cilk.

  * Added experimental parallel transforms using threads (currently,
    POSIX threads and Solaris threads are implemented and tested).

  * Added DOS support, in the sense that we now support 8.3 filenames.

Version 1.0 (3/24/1997)

  * First release.