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: April 20, 2024
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: April 20, 2024
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: April 20, 2024
