     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>

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     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

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     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:  October 22, 2020