Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / communications-1.1.1 / scatterplot.m

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+## Copyright (C) 2003 David Bateman
+##
+## 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 3 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, see <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {} scatterplot (@var{x})
+## @deftypefnx {Function File} {} scatterplot (@var{x},@var{n})
+## @deftypefnx {Function File} {} scatterplot (@var{x},@var{n},@var{off})
+## @deftypefnx {Function File} {} scatterplot (@var{x},@var{n},@var{off},@var{str})
+## @deftypefnx {Function File} {} scatterplot (@var{x},@var{n},@var{off},@var{str},@var{h})
+## @deftypefnx {Function File} {@var{h} =} scatterplot (@var{...})
+##
+## Display the scatter plot of a signal. The signal @var{x} can be either in
+## one of three forms
+##
+## @table @asis
+## @item A real vector
+## In this case the signal is assumed to be real and represented by the vector
+## @var{x}. The scatterplot is plotted along the x axis only.
+## @item A complex vector
+## In this case the in-phase and quadrature components of the signal are 
+## plotted seperately on the x and y axes respectively.
+## @item A matrix with two columns
+## In this case the first column represents the in-phase and the second the
+## quadrature components of a complex signal and are plotted on the x and
+## y axes respectively.
+## @end table
+##
+## Each point of the scatter plot is assumed to be seperated by @var{n} 
+## elements in the signal. The first element of the signal to plot is 
+## determined by @var{off}. By default @var{n} is 1 and @var{off} is 0.
+##
+## The string @var{str} is a plot style string (example 'r+'),
+## and by default is the default gnuplot point style.
+##
+## The figure handle to use can be defined by @var{h}. If @var{h} is not 
+## given, then the next available figure handle is used. The figure handle
+## used in returned on @var{hout}.
+## @end deftypefn
+## @seealso{eyediagram}
+
+## 2005-04-23 Dmitri A. Sergatskov <dasergatskov@gmail.com>
+##     * modified for new gnuplot interface (octave > 2.9.0)
+
+function varargout = scatterplot (x, n, _off, str, h)
+
+  if ((nargin < 1) || (nargin > 5))
+    usage (" h = scatterplot (x, n [, off [, str [, h]]]])");
+  endif
+  
+  if (isreal(x))
+    if (min(size(x)) == 1)
+      signal = "real";
+      xr = x(:);
+      xi = zeros(size(xr));
+    elseif (size(x,2) == 2)
+      signal = "complex";
+      xr = x(:,1);
+      xi = x(:,2);
+    else
+      error ("scatterplot: real signal input must be a vector");
+    endif
+  else
+    signal = "complex";
+    if (min(size(x)) != 1)
+      error ("scatterplot: complex signal input must be a vector");
+    endif
+    xr = real(x(:));
+    xi = imag(x(:));
+  endif
+  
+  if (!length(xr))
+    error ("scatterplot: zero length signal");
+  endif
+  
+  if (nargin > 1)
+    if (!isscalar(n) || !isreal(n) || (floor(n) != n) || (n < 1))
+      error ("scatterplot: n must be a positive non-zero integer");
+    endif
+  else
+    n = 1;
+  endif
+  
+  if (nargin > 2)
+    if (!isscalar(_off) || !isreal(_off) || (floor(_off) != _off) || ...
+       (_off < 0) || (_off > length(x)-1))
+      error ("scatterplot: offset must be an integer between 0 and length(x)-1");
+    endif
+    off = _off;
+  else
+    off = 0;
+  endif
+
+  if (nargin > 3)
+    if (isempty(str))
+      fmt = "-r";
+    elseif (ischar(str))
+      fmt = str;
+    else
+      error ("scatterplot: plot format must be a string");
+    endif
+  else
+    fmt = "-r";
+  endif
+
+  if (nargin > 4)
+    hout = figure (h);
+  else
+    hout = figure ();
+  endif
+
+  xr = xr(off+1:n:rows(xr));
+  xi = xi(off+1:n:rows(xi));
+
+  plot(xr,xi,fmt);
+  if (!strcmp(signal,"complex"))
+    ## FIXME: What is the appropriate xrange
+    xmax = max(xr);
+    xmin = min(xr);
+    xran = xmax - xmin
+    xmax =  ceil(2 * xmax / xran) / 2 * xran;
+    xmin = floor(2 * xmin / xran) / 2 * xran;
+    axis([xmin, xmax, -1, 1]);
+  endif
+  title("Scatter plot");
+  xlabel("In-phase");
+  ylabel("Quadrature");
+  legend("off");
+
+  if (nargout > 0)
+    varargout{1} = hout;
+  endif
+
+endfunction
+
+%!demo
+%! n = 200;
+%! ovsp=5;
+%! x = 1:n;
+%! xi = [1:1/ovsp:n-0.1];
+%! y = randsrc(1,n,[1 + 1i, 1 - 1i, -1 - 1i, -1 + 1i]) ;
+%! yi = interp1(x,y,xi);
+%! noisy = awgn(yi,15,"measured");
+%! hold off;
+%! h = scatterplot(noisy,1,0,"b",1);
+%! hold on;
+%! scatterplot(noisy,ovsp,0,"r+",h);