tomwalters@0: .TH ACF 1 "15 September 1993"
tomwalters@0: 
tomwalters@0: .SH NAME
tomwalters@0: acf \- autocorrelation function of contiguous frames.
tomwalters@0: .nf
tomwalters@0: i/p and o/p data in binary shorts, (o/p data n/2 points per frame).
tomwalters@0: .fi
tomwalters@0: 
tomwalters@0: .SH SYNTAX 
tomwalters@0: acf  [arguments]  [file]
tomwalters@0: 
tomwalters@0: 
tomwalters@0: .SH DESCRIPTION
tomwalters@0: The autocorrelation function (acf) is computed using the fft.
tomwalters@0: The output framewidth is the given maximum acf lag, which must not be
tomwalters@0: greater than the input framewidth.
tomwalters@0: Each input frame is padded with zeroes to the next power of 2 larger than
tomwalters@0: either the input framewidth, or twice the required max acf lag, (whichever
tomwalters@0: is  the larger).
tomwalters@0: If necessary, extra padding can be enforced using the (silent) padding option
tomwalters@0: to add extra zeroes, padding to a larger power of 2.
tomwalters@0: The amount of extra padding is "exponential", expanding the basic size to:
tomwalters@0:    
tomwalters@0:       ( framesize + padding ) * 2**n
tomwalters@0: 
tomwalters@0: where the padding option is n.
tomwalters@0: 
tomwalters@0: 
tomwalters@0: (n=0 by default, so that no extra padding is added. When n=1 then padding is
tomwalters@0: added to double the size, and when n=2 the size is quadrupled, etc.).
tomwalters@0: The input and output frame sizes in sample points may be printed using the
tomwalters@0: "size" option.
tomwalters@0: 
tomwalters@0: 
tomwalters@0: .SH EXAMPLES
tomwalters@0: .nf
tomwalters@0: 1. To print the input and output frame sizes in sample points, 
tomwalters@0:    eg for a subsequent plotting program, use the size option:
tomwalters@0: 
tomwalters@0: acf ... size=on
tomwalters@0: 
tomwalters@0: 
tomwalters@0: 2. An acf of a waveform sampled at 10kHz, computed to a max lag 
tomwalters@0:    of 12.8ms within a frame of 12.8ms, plotting the 2nd frame in 
tomwalters@0:    a sequence of frames with frameshift 12.8ms.
tomwalters@0: 
tomwalters@0: acf samp=10kHz width=12.8ms frstep=12.8ms frame=2 lag=12.8ms file 
tomwalters@0:     | x11plot
tomwalters@0: 
tomwalters@0: 3. An animated plot of successive acf's of a waveform sampled at 
tomwalters@0:    10kHz, each computed within a frame of 12.8ms, and shifted by 
tomwalters@0:    2 sample points.
tomwalters@0: 
tomwalters@0: acf samp=10kHz width=12.8ms frstep=2p lag=12.8ms file 
tomwalters@0:     | x11play -n128
tomwalters@0: 
tomwalters@0: .fi
tomwalters@0: 
tomwalters@0: .SH COPYRIGHT 
tomwalters@0: .LP 
tomwalters@0: Copyright (c) Applied Psychology Unit, Medical
tomwalters@0: Research Council, 1995 .LP Permission to use, copy, modify, and
tomwalters@0: distribute this software without fee is hereby granted for research
tomwalters@0: purposes, provided that this copyright notice appears in all copies
tomwalters@0: and in all supporting documentation, and that the software is not
tomwalters@0: redistributed for any fee (except for a nominal shipping
tomwalters@0: charge). Anyone wanting to incorporate all or part of this software in
tomwalters@0: a commercial product must obtain a license from the Medical Research
tomwalters@0: Council.  .LP The MRC makes no representations about the suitability
tomwalters@0: of this software for any purpose.  It is provided "as is" without
tomwalters@0: express or implied warranty.  
tomwalters@0: .LP 
tomwalters@0: THE MRC DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
tomwalters@0: INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
tomwalters@0: EVENT SHALL THE A.P.U. BE LIABLE FOR ANY SPECIAL, INDIRECT OR
tomwalters@0: CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
tomwalters@0: USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
tomwalters@0: OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
tomwalters@0: PERFORMANCE OF THIS SOFTWARE.
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