update packages

[CreaPhase.git] / octave_packages / m / plot / feather.m

diff --git a/octave_packages/m/plot/feather.m b/octave_packages/m/plot/feather.m
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+## Copyright (C) 2007-2012 David Bateman
+##
+## This file is part of Octave.
+##
+## Octave 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.
+##
+## Octave 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 Octave; see the file COPYING.  If not, see
+## <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn  {Function File} {} feather (@var{u}, @var{v})
+## @deftypefnx {Function File} {} feather (@var{z})
+## @deftypefnx {Function File} {} feather (@dots{}, @var{style})
+## @deftypefnx {Function File} {} feather (@var{h}, @dots{})
+## @deftypefnx {Function File} {@var{h} =} feather (@dots{})
+##
+## Plot the @code{(@var{u}, @var{v})} components of a vector field emanating
+## from equidistant points on the x-axis.  If a single complex argument
+## @var{z} is given, then @code{@var{u} = real (@var{z})} and
+## @code{@var{v} = imag (@var{z})}.
+##
+## The style to use for the plot can be defined with a line style @var{style}
+## in a similar manner to the line styles used with the @code{plot} command.
+##
+## The optional return value @var{h} is a vector of graphics handles to the
+## line objects representing the drawn vectors.
+##
+## @example
+## @group
+## phi = [0 : 15 : 360] * pi/180;
+## feather (sin (phi), cos (phi));
+## @end group
+## @end example
+##
+## @seealso{plot, quiver, compass}
+## @end deftypefn
+
+function retval = feather (varargin)
+
+  [h, varargin, nargin] = __plt_get_axis_arg__ ("feather", varargin{:});
+
+  arrowsize = 0.25;
+
+  if (nargin == 0)
+    print_usage ();
+  elseif (nargin == 1 || (nargin == 2 && ! isnumeric (varargin{2})))
+    ioff = 2;
+    z = varargin{1}(:).';
+    u = real (z);
+    v = imag (z);
+  elseif (nargin > 1 && isnumeric (varargin{2}))
+    ioff = 3;
+    u = varargin{1}(:).';
+    v = varargin{2}(:).';
+  endif
+
+  line_spec = "b-";
+  have_line_spec = false;
+  while (ioff <= nargin)
+    arg = varargin{ioff++};
+    if ((ischar (arg) || iscell (arg)) && ! have_line_spec)
+      [linespec, valid] = __pltopt__ ("feather", arg, false);
+      if (valid)
+        line_spec = arg;
+        have_line_spec = false;
+        break;
+      else
+        error ("feather: invalid linespec");
+      endif
+    else
+      error ("feather: unrecognized argument");
+    endif
+  endwhile
+
+  ## Matlab draws feather plots, with the arrow head as one continous
+  ## line, and each arrow separately. This is completely different than
+  ## quiver and quite ugly.
+  n = length (u);
+  xend = [1 : n] + u;
+  xtmp = [1 : n] + u .* (1 - arrowsize);
+  yend = v;
+  ytmp = v .* (1 - arrowsize);
+  x = [[1 : n]; xend; xtmp  - v * arrowsize; xend; ...
+       xtmp + v * arrowsize];
+  y = [zeros(1, n); yend; ytmp  + u * arrowsize / 3; yend; ...
+       ytmp - u * arrowsize / 3];
+
+  oldh = gca ();
+  unwind_protect
+    axes (h);
+    newplot ();
+    hlist = plot (h, x, y, line_spec, [1, n], [0, 0], line_spec);
+  unwind_protect_cleanup
+    axes (oldh);
+  end_unwind_protect
+
+  if (nargout > 0)
+    retval = hlist;
+  endif
+
+endfunction
+
+
+%!demo
+%! clf
+%! phi = [0 : 15 : 360] * pi / 180;
+%! feather (sin (phi), cos (phi))
+