1## Copyright (C) 1998, 2000, 2004, 2005, 2007
2##               Auburn University.  All rights reserved.
3##
4##
5## This program 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## This program 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 this program; see the file COPYING.  If not, see
17## <http://www.gnu.org/licenses/>.
18
19## -*- texinfo -*-
20## @deftypefn {Function File} {} __axis_limits__ (@var{axdata})
21## Determine axis limits for 2-D data (column vectors); leaves a 10%
22## margin around the plots.
23## Inserts margins of +/- 0.1 if data is one-dimensional
24## (or a single point).
25##
26## @strong{Input}
27## @table @var
28## @item axdata
29## @var{n} by 2 matrix of data [@var{x}, @var{y}].
30## @end table
31##
32## @strong{Output}
33## @table @var
34## @item axvec
35## Vector of axis limits appropriate for call to @command{axis} function.
36## @end table
37## @end deftypefn
38
39function axvec = __axis_limits__ (axdata)
40
41  if (nargin < 1 || isempty (axdata))
42    axdata = 0;
43  endif
44
45  ## compute axis limits
46  minv = min (axdata);
47  maxv = max (axdata);
48  delv = (maxv-minv)/2;             # breadth of the plot
49  midv = (minv + maxv)/2;           # midpoint of the plot
50  axmid = [midv(1), midv(1), midv(2), midv(2)];
51  axdel = [-0.1, 0.1, -0.1, 0.1];   # default plot width (if less than 2-d data)
52  if (max (delv) == 0)
53    if (midv(1) != 0)
54      axdel(1:2) = [-0.1*midv(1), 0.1*midv(1)];
55    endif
56    if (midv(2) != 0)
57      axdel(3:4) = [-0.1*midv(2), 0.1*midv(2)];
58    endif
59  else
60    ## they're at least one-dimensional
61    tolv = max(1e-8, 1e-8*abs(midv));
62    if (abs (delv(1)) >= tolv(1))
63      axdel(1:2) = 1.1*[-delv(1),delv(1)];
64    endif
65    if (abs (delv(2)) >= tolv(2))
66      axdel(3:4) = 1.1*[-delv(2),delv(2)];
67    endif
68  endif
69  axvec = axmid + axdel;
70
71endfunction
72