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comparison scripts/plot/feather.m @ 7322:40a17a87155e

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[project @ 2007-12-18 21:32:10 by jwe]
author jwe
date Tue, 18 Dec 2007 21:34:26 +0000
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7321:359f464342b3 7322:40a17a87155e
1 ## Copyright (C) 2007 David Bateman
2 ##
3 ## This file is part of Octave.
4 ##
5 ## Octave is free software; you can redistribute it and/or modify it
6 ## under the terms of the GNU General Public License as published by
7 ## the Free Software Foundation; either version 3 of the License, or (at
8 ## your option) any later version.
9 ##
10 ## Octave is distributed in the hope that it will be useful, but
11 ## WITHOUT ANY WARRANTY; without even the implied warranty of
12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 ## General Public License for more details.
14 ##
15 ## You should have received a copy of the GNU General Public License
16 ## along with Octave; see the file COPYING. If not, see
17 ## <http://www.gnu.org/licenses/>.
18
19 ## -*- texinfo -*-
20 ## @deftypefn {Function File} {} feather (@var{u}, @var{v})
21 ## @deftypefnx {Function File} {} feather (@var{z})
22 ## @deftypefnx {Function File} {} feather (@dots{}, @var{style})
23 ## @deftypefnx {Function File} {} feather (@var{h}, @dots{})
24 ## @deftypefnx {Function File} {@var{h} =} feather (@dots{})
25 ##
26 ## Plot the @code{(@var{u}, @var{v})} components of a vector field emanating
27 ## from equidistant points on the x-axis. If a single complex argument
28 ## @var{z} is given, then @code{@var{u} = real (@var{z})} and
29 ## @code{@var{v} = imag (@var{z})}.
30 ##
31 ## The style to use for the plot can be defined with a line style @var{style}
32 ## in a similar manner to the line styles used with the @code{plot} command.
33 ##
34 ## The optional return value @var{h} provides a list of handles to the
35 ## the parts of the vector field (body, arrow and marker).
36 ##
37 ## @example
38 ## @group
39 ## phi = [0 : 15 : 360] * pi / 180;
40 ## feather (sin (phi), cos (phi))
41 ## @end group
42 ## @end example
43 ##
44 ## @seealso{plot, quiver, compass}
45 ## @end deftypefn
46
47 function retval = feather (varargin)
48
49 [h, varargin, nargin] = __plt_get_axis_arg__ ("feather", varargin{:});
50
51 arrowsize = 0.25;
52 firstnonnumeric = Inf;
53 for i = 1:nargin
54 if (! isnumeric (varargin{i}))
55 firstnonnumeric = i;
56 break;
57 endif
58 endfor
59
60 if (nargin < 2 || firstnonnumeric < 2)
61 ioff = 2;
62 z = varargin {1} (:) .';
63 u = real (z);
64 v = imag (z);
65 else
66 ioff = 3;
67 u = varargin {1} (:) .';
68 v = varargin {2} (:) .';
69 endif
70
71 line_spec = "b-";
72 while (ioff <= nargin)
73 arg = varargin{ioff++};
74 if ((isstr (arg) || iscell (arg)) && ! have_line_spec)
75 [linespec, valid] = __pltopt__ ("feather", arg, false);
76 if (valid)
77 line_spec = arg;
78 break;
79 else
80 error ("feather: invalid linespec");
81 endif
82 else
83 error ("feather: unrecognized argument");
84 endif
85 endwhile
86
87 ## Matlab draws feather plots, with the arrow head as one continous
88 ## line, and each arrow separately. This is completely different than
89 ## quiver and quite ugly.
90 n = length (u);
91 xend = [1 : n] + u;
92 xtmp = [1 : n] + u .* (1 - arrowsize);
93 yend = v;
94 ytmp = v .* (1 - arrowsize);
95 x = [[1 : n]; xend; xtmp - v * arrowsize; xend; ...
96 xtmp + v * arrowsize];
97 y = [zeros(1, n); yend; ytmp + u * arrowsize / 3; yend; ...
98 ytmp - u * arrowsize / 3];
99
100 oldh = gca ();
101 unwind_protect
102 axes (h);
103 newplot ();
104 hlist = plot (h, x, y, line_spec, [1, n], [0, 0], line_spec);
105 unwind_protect_cleanup
106 axes (oldh);
107 end_unwind_protect
108
109 if (nargout > 0)
110 retval = hlist;
111 endif
112
113 endfunction
114
115 %!demo
116 %! phi = [0 : 15 : 360] * pi / 180;
117 %! feather (sin (phi), cos (phi))