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

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

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

       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:

       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 wis‐
       dom file, with the -w option).

       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  (white‐
       space-separated), if a SIZE argument of "-" is supplied.

       Sizes are specified by the syntax:


       <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 (back‐
       wards)  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).

       -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, out‐
              putting accumulated wisdom.  (The problems are planned
              in increasing order of size.)  Defaults to 0, indicat‐
              ing 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
              respectively, as described in more detail by the  FFTW

              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.

       Send bug reports to

       Written by Steven G. Johnson and Matteo Frigo.

       Copyright (c) 2003, 2007-8 Matteo Frigo
       Copyright  (c)  2003, 2007-8 Massachusetts Institute of Tech‐


fftw                       February, 2003             FFTW-WISDOM(1)
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