diff man/man1/filt1.1 @ 0:5242703e91d3 tip

Initial checkin for AIM92 aimR8.2 (last updated May 1997).

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+.TH FILT1 1 "1 September 1993"
+
+.SH NAME
+filt1 \- 1st order LP filter using an exponential smoother.
+
+.SH SYNTAX 
+filt1 [options] [file]
+
+.SH DESCRIPTION
+A recursive "leaky integrator" 1st order low-pass filter which is a shifting
+exponential window which decays into the past values.
+
+.SH OPTIONS
+
+1. tc
+
+The time-constant parameter which controls the rate of decay and so the
+size of the exponential window. For a given time constant of T seconds:
+
+.nf
+	0.7T secs   is the window half--life.
+	4.6T secs   is 99% of the window's life.
+.fi
+
+When the time-constant parameter is given with time units (s or ms) then
+it is converted to a decay constant using  a = exp(-Ts/T),
+where Ts is the sample interval in seconds from the given `samplerate' option,
+and T  is decay time-constant in seconds.
+Otherwise the time-constant parameter is taken to be the decay constant directly.
+
+With decay constant a=1 there is infinite memory because it does not decay.
+With 0 < a < 1 there is a finite decaying memory.
+The smaller `a', the smaller the memory (it decays faster).
+With a = 0 the filter output is identical with its input.
+
+2. de
+
+Two optional difference equations are provided which repsectively compute
+a recursive sum (when "de=sum") and mean (when "de=mean").
+The n'th recursive update is respectively:
+
+.nf
+	y[n] = a.y[n-1] + x[n]                recursive sum
+	y[n] = a.y[n-1] + (1-a).x[n]          recursive mean
+.fi
+
+where decay constant a = exp(-Ts/T),
+Ts is the sample interval in seconds, and T  is decay time-constant in seconds.
+
+.SH "SEE ALSO"
+options smooth
+
+.SH COPYRIGHT
+.LP
+Copyright (c) Applied Psychology Unit, Medical Research Council, 1995
+.LP
+Permission to use, copy, modify, and distribute this software without fee 
+is hereby granted for research purposes, provided that this copyright 
+notice appears in all copies and in all supporting documentation, and that 
+the software is not redistributed for any fee (except for a nominal 
+shipping charge). Anyone wanting to incorporate all or part of this 
+software in a commercial product must obtain a license from the Medical 
+Research Council.
+.LP
+The MRC makes no representations about the suitability of this 
+software for any purpose.  It is provided "as is" without express or 
+implied warranty.
+.LP
+THE MRC DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING 
+ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL 
+THE A.P.U. BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES 
+OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, 
+WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, 
+ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS 
+SOFTWARE.
+