--- /dev/null
+## Copyright (C) 1998, 2000, 2004, 2005, 2007
+## Auburn University. All rights reserved.
+##
+##
+## This program 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.
+##
+## This program 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 this program; see the file COPYING. If not, see
+## <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {} __axis_margin__ (@var{axdata})
+## Determine axis limits for 2-D data (column vectors); leaves a 10%
+## margin around the plots.
+## Inserts margins of +/- 0.1 if data is one-dimensional
+## (or a single point).
+##
+## @strong{Input}
+## @table @var
+## @item axdata
+## @var{n} by 2 matrix of data [@var{x}, @var{y}].
+## @end table
+##
+## @strong{Output}
+## @table @var
+## @item axvec
+## Vector of axis limits appropriate for call to @command{axis} function.
+## @end table
+## @end deftypefn
+
+function axvec = __axis_margin__ (axdata)
+
+ ## compute axis limits
+ minv = axdata(1);
+ maxv = axdata(2);
+ delv = (maxv-minv)/2; # breadth of the plot
+ midv = (minv + maxv)/2; # midpoint of the plot
+ axmid = [midv, midv];
+ axdel = [-0.1, 0.1]; # default plot width (if less than 2-d data)
+
+ if (delv == 0)
+ if (midv != 0)
+ axdel = [-0.1*midv, 0.1*midv];
+ endif
+ else
+ ## they're at least one-dimensional
+ tolv = max(1e-8, 1e-8*abs(midv));
+ if (abs (delv) >= tolv)
+ axdel = 1.1*[-delv,delv];
+ endif
+ endif
+
+ axvec = axmid + axdel;
+
+endfunction