packages icon



 FFTW-WISDOM(1)                     fftw                      FFTW-WISDOM(1)
 fftw                                                                   fftw

                               February, 2003



 NAME
      fftw-wisdom - create wisdom (pre-optimized FFTs)

 SYNOPSIS
      fftw-wisdom [OPTION]... [SIZE]...

 DESCRIPTION
      fftw-wisdom is a utility to generate FFTW wisdom files, which contain
      saved information about how to optimally compute (Fourier) transforms
      of various sizes.  FFTW is a free library to compute discrete Fourier
      transforms in one or more dimensions, for arbitrary sizes, and of both
      real and complex data, among other related operations.  More
      information on FFTW can be found at the FFTW home page:
      http://www.fftw.org

      Programs using FFTW can be written to load wisdom from an arbitrary
      file, string, or other source.  Moreover, it is likely that many
      FFTW-using programs will load the system wisdom file, which is stored
      in /etc/fftw/wisdom by default.  fftw-wisdom can be used to create or
      add to such wisdom files.  In its most typical usage, the wisdom file
      can be created to pre-plan a canonical set of sizes (see below) via:

                           fftw-wisdom -v -c -o wisdom

      (this will take many hours, which can be limited by the -t option) and
      the output wisdom file can then be copied (as root) to /etc/fftw/ or
      whatever.

      The fftw-wisdom program normally writes the wisdom directly to
      standard output, but this can be changed via the -o option, as in the
      example above.

      If the system wisdom file /etc/fftw/wisdom already exists, then
      fftw-wisdom reads this existing wisdom (unless the -n option is
      specified) and outputs both the old wisdom and any newly created
      wisdom.  In this way, it can be used to add new transform sizes to the
      existing system wisdom (or other wisdom file, with the -w option).

 SPECIFYING SIZES
      Although a canonical set of sizes to optimize is specified by the -c
      option, the user can also specify zero or more non-canonical transform
      sizes and types to optimize, via the SIZE arguments following the
      option flags.  Alternatively, the sizes to optimize can be read from
      standard input (whitespace-separated), if a SIZE argument of "-" is
      supplied.

      Sizes are specified by the syntax:

                       <type><inplace><direction><geometry>



                                    - 1 -       Formatted:  December 4, 2021






 FFTW-WISDOM(1)                     fftw                      FFTW-WISDOM(1)
 fftw                                                                   fftw

                               February, 2003



      <type> is either 'c' (complex), 'r' (real, r2c/c2r), or 'k' (r2r,
      per-dimension kinds, specified in the geometry, below).

      <inplace> is either 'i' (in place) or 'o' (out of place).

      <direction> is either 'f' (forward) or 'b' (backward).  The
      <direction> should be omitted for 'k' transforms, where it is
      specified via the geometry instead.

      <geometry> is the size and dimensionality of the transform, where
      different dimensions are separated by 'x' (e.g. '16x32' for a two-
      dimensional 16 by 32 transform).  In the case of 'k' transforms, the
      size of each dimension is followed by a "type" string, which can be
      one of f/b/h/e00/e01/e10/e11/o00/o01/o10/o11 for
      R2HC/HC2R/DHT/REDFT00/.../RODFT11, respectively, as defined in the
      FFTW manual.

      For example, 'cif12x13x14' is a three-dimensional 12 by 13 x 14
      complex DFT operating in-place.  'rob65536' is a one-dimensional
      size-65536 out-of-place complex-to-real (backwards) transform
      operating on Hermitian-symmetry input.  'ki10hx20e01' is a two-
      dimensional 10 by 20 r2r transform where the first dimension is a DHT
      and the second dimension is an REDFT01 (DCT-III).


 OPTIONS
      -h, --help
           Display help on the command-line options and usage.

      -V, --version
           Print the version number and copyright information.

      -v, --verbose
           Verbose output.  (You can specify this multiple times, or supply
           a numeric argument greater than 1, to increase the verbosity
           level.)  Note that the verbose output will be mixed with the
           wisdom output (making it impossible to import), unless you write
           the wisdom to a file via the -o option.

      -c, --canonical
           Optimize/pre-plan a canonical set of sizes: all powers of two and
           ten up to 2^20 (1048576), including both real and complex,
           forward and backwards, in-place and out-of-place transforms.
           Also includes two- and three-dimensional transforms of equal-size
           dimensions (e.g. 16x16x16).

      -t hours, --time-limit=hours
           Stop after a time of hours (hours) has elapsed, outputting
           accumulated wisdom.  (The problems are planned in increasing



                                    - 2 -       Formatted:  December 4, 2021






 FFTW-WISDOM(1)                     fftw                      FFTW-WISDOM(1)
 fftw                                                                   fftw

                               February, 2003



           order of size.)  Defaults to 0, indicating no time limit.

      -o file, --output-file=file
           Send wisdom output to file rather than to standard output (the
           default).

      -m, --measure; -e, --estimate; -x, --exhaustive
           Normally, fftw-wisdom creates plans in FFTW_PATIENT mode, but
           with these options you can instead use FFTW_MEASURE,
           FFTW_ESTIMATE, or FFTW_EXHAUSTIVE modes, respectively, as
           described in more detail by the FFTW manual.

           Note that wisdom is tagged with the planning patience level, and
           a single file can mix different levels of wisdom (e.g. you can
           mostly use the patient default, but plan a few sizes that you
           especially care about in --exhaustive mode).

      -n, --no-system-wisdom
           Do not import the system wisdom from /etc/fftw/wisdom (which is
           normally read by default).

      -w file, --wisdom-file=file
           Import wisdom from file (in addition to the system wisdom, unless
           -n is specified).  Multiple wisdom files can be read via multiple
           -w options.  If file is "-", then read wisdom from standard
           input.

      -T N, --threads=N
           Plan with N threads.  This option is only present if FFTW was
           configured with thread support.

 BUGS
      Send bug reports to fftw@fftw.org.

 AUTHORS
      Written by Steven G. Johnson and Matteo Frigo.

      Copyright (c) 2003, 2007-14 Matteo Frigo
      Copyright (c) 2003, 2007-14 Massachusetts Institute of Technology

 SEE ALSO
      fftw-wisdom-to-conf(1)










                                    - 3 -       Formatted:  December 4, 2021