--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main/signal/pulstran.m	Wed Oct 10 19:54:49 2001 +0000
@@ -0,0 +1,150 @@
+## Copyright (C) 2000 Paul Kienzle
+##
+## This program is free software; you can redistribute it and/or modify
+## it under the terms of the GNU General Public License as published by
+## the Free Software Foundation; either version 2 of the License, or
+## (at your option) any later version.
+##
+## This program is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with this program; if not, write to the Free Software
+## Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+
+## usage: y=pulstran(t,d,'func',...)
+##        y=pulstran(t,d,p,Fs,'interp')
+##
+## Generate the signal y=sum(func(t+d,...)) for each d.  If d is a
+## matrix of two columns, the first column is the delay d and the second
+## column is the amplitude a, and y=sum(a*func(t+d)) for each d,a.
+## Clearly, func must be a function which accepts a vector of times.
+## Any extra arguments needed for the function must be tagged on the end.
+##
+## Example
+##   fs = 11025;  # arbitrary sample rate
+##   f0 = 100;    # pulse train sample rate
+##   w = 0.001;   # pulse width of 1 millisecond
+##   auplot(pulstran(0:1/fs:0.1, 0:1/f0:0.1, 'rectpuls', w), fs);
+##
+## If instead of a function name you supply a pulse shape sampled at
+## frequency Fs (default 1 Hz),  an interpolated version of the pulse
+## is added at each delay d.  The interpolation stays within the the
+## time range of the delayed pulse.  The interpolation method defaults
+## to linear, but it can be any interpolation method accepted by the
+## function interp1.
+##
+## Example
+##   fs = 11025;  # arbitrary sample rate
+##   f0 = 100;    # pulse train sample rate
+##   w = boxcar(10);  # pulse width of 1 millisecond at 10 kHz
+##   auplot(pulstran(0:1/fs:0.1, 0:1/f0:0.1, w, 10000), fs);
+
+## TODO: Make it faster.  It is currently unusable for anything real.
+## TODO: It may not be possible to speed it up with the present interface.
+## TODO: See speech/voice.m for a better way.
+
+## Note that pulstran can be used for some pretty strange things such
+## as simple band-limited interpolation:
+##     xf = 0:0.05:10; yf = sin(2*pi*xf/5);
+##     xp = 0:10; yp = sin(2*pi*xp/5); # .2 Hz sine sampled every second
+##     s = pulstran(xf, [xp, yp],'sinc'); 
+##     plot(f, yf, ";original;", xf, s, ";sinc;",xp,yp,"*;;");
+## You wouldn't want to do this in practice since it is expensive, and
+## since it works much better with a windowed sinc function, at least
+## for short samples.
+
+function y = pulstran(t, d, pulse, ...) ##<oct
+##<mat function y = pulstran(t, d, pulse, varargin)
+
+  if nargin<3 || (!isstr(pulse) && nargin>5)
+    error("y=pulstran(t,d,'func',...) or y==pulstran(t,d,p,Fs,'interp')");
+  endif
+  y = zeros(size(t));
+  if isempty(y), return; endif
+  if rows(d) == 1, d=d'; endif
+  if columns(d) == 2, 
+    a=d(:,2);
+  else
+    a=ones(rows(d),1);
+  endif
+  if isstr(pulse) 
+    ## apply function t+d for all d
+    for i=1:rows(d)
+      y = y+a(i)*feval(pulse,t-d(i,1),all_va_args); ##<oct
+      ##<mat y = y+a(i)*feval(pulse,t-d(i,1),varargin{:});
+    endfor
+  else
+    ## interpolate each pulse at the specified times
+    Fs = 1; method = 'linear';
+    if nargin==4
+      arg = va_arg();  ##<oct
+      ##<mat arg=varargin{1};
+      if isstr(arg), 
+	method=arg;
+      else
+	Fs = arg;
+      endif
+    elseif nargin==5
+      Fs=va_arg();     ##<oct
+      method=va_arg(); ##<oct
+      ##<mat Fs = varargin{1};
+      ##<mat method = varargin{2};
+    endif
+    span = (length(pulse)-1)/Fs;
+    t_pulse = (0:length(pulse)-1)/Fs;
+    for i=1:rows(d)
+      dt = t-d(i,1);
+      idx = find(dt>=0 & dt<=span);
+      y(idx) = y(idx) + a(i)*interp1(t_pulse, pulse, dt(idx), method);
+    endfor
+  endif
+endfunction
+
+%!error pulstran
+%!error pulstran(1,2,3,4,5,6)
+
+%!## parameter size and shape checking
+%!shared t,d
+%! t = 0:0.01:1; d=0:0.1:1;
+%!assert (isempty(pulstran([], d, 'sin')));
+%!assert (pulstran(t, [], 'sin'), zeros(size(t)));
+%!assert (isempty(pulstran([], d, boxcar(5))));
+%!assert (pulstran(t, [], boxcar(5)), zeros(size(t)));
+%!assert (size(pulstran(t,d,'sin')), size(t));
+%!assert (size(pulstran(t,d','sin')), size(t));
+%!assert (size(pulstran(t',d,'sin')), size(t'));
+%!assert (size(pulstran(t,d','sin')), size(t));
+
+%!demo
+%! fs = 11025;                   # arbitrary sample rate
+%! f0 = 100;                     # pulse train sample rate
+%! w = 0.003;                    # pulse width of 3 milliseconds
+%! t = 0:1/fs:0.1; d=0:1/f0:0.1; # define sample times and pulse times 
+%! a = hanning(length(d));       # define pulse amplitudes
+%!
+%! subplot(221); title("rectpuls");
+%! auplot(pulstran(t', d', 'rectpuls', w), fs);
+%! hold on; plot(d*1000,ones(size(d)),'g*;pulse;'); hold off;
+%!
+%! subplot(223); title("sinc => band limited interpolation");
+%! auplot(pulstran(f0*t, [f0*d', a], 'sinc'), fs);
+%! hold on; plot(d*1000,a,'g*;pulse;'); hold off;
+%!
+%! subplot(222); title("interpolated boxcar");
+%! pulse = boxcar(30);  # pulse width of 3 ms at 10 kHz
+%! auplot(pulstran(t, d', pulse, 10000), fs);
+%! hold on; plot(d*1000,ones(size(d)),'g*;pulse;'); hold off;
+%!
+%! subplot(224); title("interpolated asymmetric sin");
+%! pulse = sin(2*pi*[0:0.0001:w]/w).*[w:-0.0001:0];
+%! auplot(pulstran(t', [d', a], pulse', 10000), fs);
+%! hold on; plot(d*1000,a*w,'g*;pulse;'); hold off; title("");
+%! oneplot();
+%! %----------------------------------------------------------
+%! % Should see (1) rectangular pulses centered on *,
+%! %            (2) rectangular pulses to the right of *,
+%! %            (3) smooth interpolation between the *'s, and
+%! %            (4) asymetric sines to the right of *