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scripts/plot/compass.m

changeset 10289: 4b124317dc38
parent:16f53d29049f
author: John W. Eaton <jwe@octave.org>
date: Tue Feb 09 20:58:55 2010 -0500 (29 minutes ago)
permissions: -rw-r--r--
description: base_properties::set_children: account for hidden children 
     1## Copyright (C) 2007, 2008, 2009 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} {} compass (@var{u}, @var{v})

    21## @deftypefnx {Function File} {} compass (@var{z})

    22## @deftypefnx {Function File} {} compass (@dots{}, @var{style})

    23## @deftypefnx {Function File} {} compass (@var{h}, @dots{})

    24## @deftypefnx {Function File} {@var{h} =} compass (@dots{})

    25##

    26## Plot the @code{(@var{u}, @var{v})} components of a vector field emanating

    27## from the origin of a polar plot.  If a single complex argument @var{z} is 

    28## given, then @code{@var{u} = real (@var{z})} and @code{@var{v} = imag 

    29## (@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## a = toeplitz([1;randn(9,1)],[1,randn(1,9)]);

    40## compass (eig (a))

    41## @end group

    42## @end example

    43##

    44## @seealso{plot, polar, quiver, feather}

    45## @end deftypefn

    46

    47function retval = compass (varargin)

    48

    49  [h, varargin, nargin] = __plt_get_axis_arg__ ("compass", varargin{:});

    50

    51  arrowsize = 0.25;

    52

    53  if (nargin == 0)

    54    print_usage ();

    55  elseif (nargin == 1 || (nargin == 2 && ! isnumeric (varargin{2})))

    56    ioff = 2;

    57    z = varargin{1}(:).';

    58    u = real (z);

    59    v = imag (z);

    60  elseif (nargin > 1 && isnumeric (varargin{2}))

    61    ioff = 3;

    62    u = varargin{1}(:).';

    63    v = varargin{2}(:).';

    64  endif

    65

    66  line_spec = "b-";

    67  have_line_spec = false;

    68  while (ioff <= nargin)

    69    arg = varargin{ioff++};

    70    if ((ischar (arg) || iscell (arg)) && ! have_line_spec)

    71      [linespec, valid] = __pltopt__ ("compass", arg, false);

    72      if (valid)

    73	line_spec = arg;

    74	have_line_spec = true;

    75	break;

    76      else

    77	error ("compass: invalid linespec");

    78      endif

    79    else

    80      error ("compass: unrecognized argument");

    81    endif

    82  endwhile

    83

    84  ## Matlab draws compass plots, with the arrow head as one continous 

    85  ## line, and each arrow separately. This is completely different than 

    86  ## quiver and quite ugly.

    87  n = length (u);

    88  xend = u;

    89  xtmp = u .* (1 - arrowsize);

    90  yend = v;

    91  ytmp = v .* (1 - arrowsize);

    92  x = [zeros(1, n); xend; xtmp  - v * arrowsize / 3; xend; ...

    93       xtmp + v * arrowsize / 3];

    94  y = [zeros(1, n); yend; ytmp  + u * arrowsize / 3; yend; ...

    95       ytmp - u * arrowsize / 3];

    96  [r, p] = cart2pol (x, y);

    97

    98  oldh = gca ();

    99  unwind_protect

   100    axes (h);

   101    newplot ();

   102    hlist = polar (h, r, p, line_spec);

   103  unwind_protect_cleanup

   104    axes (oldh);

   105  end_unwind_protect

   106

   107  if (nargout > 0)

   108    retval = hlist;

   109  endif

   110

   111endfunction

   112

   113%!demo

   114%! a = toeplitz([1;randn(9,1)],[1,randn(1,9)]);

   115%! compass (eig (a))