--- a/scripts/plot/Makefile.in	Mon Nov 26 23:06:13 2007 +0000
+++ b/scripts/plot/Makefile.in	Mon Nov 26 23:13:40 2007 +0000
@@ -111,6 +111,7 @@
   peaks.m \
   pie.m \
   plot.m \
+  plotyy.m \
   plot3.m \
   plotyy.m \
   polar.m \

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/scripts/plot/plotyy.m	Mon Nov 26 23:13:40 2007 +0000
@@ -0,0 +1,118 @@
+## Copyright (C) 2007 David Bateman
+##
+## This file is part of Octave.
+##
+## Octave 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.
+##
+## Octave 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 Octave; see the file COPYING.  If not, see
+## <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {} plotyy (@var{x1}, @var{y1}, @var{x2}, @var{y2})
+## @deftypefnx {Function File} {} plotyy (@dots{}, @var{fun})
+## @deftypefnx {Function File} {} plotyy (@dots{}, @var{fun1}, @var{fun2})
+## @deftypefnx {Function File} {} plotyy (@var{h}, @dots{})
+## @deftypefnx {Function File} {[@var{ax}, @var{h1}, @var{h2}] =} plotyy (@dots{})
+## Plots two sets of data with independent y-axes. The arguments @var{x1} and
+## @var{y1} define the arguments for the first plot and @var{x1} and @var{y2}
+## for the second. 
+##
+## By default the arguments are evaluated with 
+## @code{feval (@@plot, @var{x}, @var{y})}. However the type of plot can be
+## modified with the @var{fun} argument, in which case the plots are
+## generated by @code{feval (@var{fun}, @var{x}, @var{y})}. @var{fun} can be 
+## a function handle, an inline function or a string of a function name.
+##
+## The function to use for each of the plots can be independently defined 
+## with @var{fun1} and @var{fun2}.
+##
+## If given, @var{h} defines the principal axis in which to plot the @var{x1}
+## and @var{y1} data. The return value @var{ax} is a two element vector with
+## the axis handles of the two plots. @var{h1} and @var{h2} are handles to
+## the objects generated by the plot commands.
+##
+## @example
+## @group
+## x = 0:0.1:2*pi; 
+## y1 = sin (x);
+## y2 = exp(x - 1);
+## ax = plotyy(x, y1, x - 1, y2, @@plot, @@semilogy);
+## xlabel ("X");
+## ylabel (ax(1), "Axis 1");
+## ylabel (ax(2), "Axis 2");
+## @end group
+## @end example
+## @end deftypefn
+
+function [Ax, H1, H2] = plotyy (varargin)
+
+  if (isscalar (varargin{1}) && ishandle (varargin{1}))
+    ax = varargin {1};
+    if (! strcmp (get (ax, "type"), "axes"))
+      error ("plotyy: expecting first argument to be an axes object");
+    endif
+    if (nargin < 5)
+      print_usage();
+    endif
+    oldh = gca ();
+    unwind_protect
+      axes (ax);
+      newplot ();
+      [ax, h1, h2] = __plotyy__ (ax, varargin{2:end});
+    unwind_protect_cleanup
+      axes (oldh);
+    end_unwind_protect
+  else
+    if (nargin < 4)
+      print_usage();
+    endif
+    newplot ();
+    [ax, h1, h2] = __plotyy__ (gca (), varargin{:});
+  endif
+
+  if (nargout > 0)
+    Ax = ax;
+    H1 = h1;
+    H2 = h2;
+  endif
+endfunction
+
+function [ax, h1, h2] = __plotyy__ (ax, x1, y1, x2, y2, varargin)
+  if (nargin > 5)
+    fun1 = varargin{1};
+  else
+    fun1 = @plot;
+  endif
+  if (nargin > 6)
+    fun2 = varargin{2};
+  else
+    fun2 = fun1;
+  endif
+
+  xlim = [min([x1(:); x2(:)]), max([x1(:); x2(:)])];
+
+  h1 = feval (fun1, x1, y1);
+  set (ax(1), "ycolor", get (h1, "color"));
+  set (ax(1), "position", get (ax(1), "outerposition"));
+  set (ax(1), "xlim", xlim);
+
+  cf = gcf ();
+  set (cf, "nextplot", "add");
+  ax(2) = axes ("position", get (ax(1), "position"));
+  colors = get (ax(1), "colororder");
+  set (ax(2), "colororder", [colors(2:end,:); colors(1,:)]);
+
+  h2 = feval (fun2, x2, y2);
+  set (ax(2), "ycolor", get (h2, "color"));
+  set (ax(2), "xlim", xlim);
+  set (ax(2), "yaxislocation", "right");
+endfunction