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