--- a/scripts/plot/draw/plotyy.m	Thu Jan 23 10:38:10 2014 -0500
+++ b/scripts/plot/draw/plotyy.m	Thu Jan 23 10:44:24 2014 -0800
@@ -22,7 +22,7 @@
 ## @deftypefnx {Function File} {} plotyy (@dots{}, @var{fun1}, @var{fun2})
 ## @deftypefnx {Function File} {} plotyy (@var{hax}, @dots{})
 ## @deftypefnx {Function File} {[@var{ax}, @var{h1}, @var{h2}] =} plotyy (@dots{})
-## Plot two sets of data with independent y-axes.
+## Plot two sets of data with independent y-axes and a common x-axis.
 ##
 ## The arguments @var{x1} and @var{y1} define the arguments for the first plot
 ## and @var{x1} and @var{y2} for the second.
@@ -40,7 +40,7 @@
 ## the principal axis in which to plot the @var{x1} and @var{y1} data.
 ##
 ## The return value @var{ax} is a vector with the axis handles of the two
-## y axes.  @var{h1} and @var{h2} are handles to the objects generated by the
+## y-axes.  @var{h1} and @var{h2} are handles to the objects generated by the
 ## plot commands.
 ##
 ## @example
@@ -57,113 +57,66 @@
 ## @seealso{plot}
 ## @end deftypefn
 
-function [Ax, H1, H2] = plotyy (varargin)
+function [ax, h1, h2] = plotyy (varargin)
 
-  ## Don't use __plt_get_axis_arg__ here as ax is a two vector for plotyy
-  if (nargin > 1 && length (varargin{1}) == 2 && ishandle (varargin{1}(1))
-      && ishandle (varargin{1}(2))
-      && all (floor (varargin{1}) != varargin{1}))
-    obj1 = get (varargin{1}(1));
-    obj2 = get (varargin{1}(2));
-    if (strcmp (obj1.type, "axes") || strcmp (obj2.type, "axes"))
-      ax = [obj1, obj2];
-      varargin(1) = [];
-      if (isempty (varargin))
-        varargin = {};
-      endif
-    else
-      error ("plotyy: expecting first argument to be axes handle");
-    endif
-    oldh = gca ();
-  else
-    f = get (0, "currentfigure");
-    if (isempty (f))
-      f = figure ();
-    endif
-    ca = get (f, "currentaxes");
-    if (isempty (ca))
-      ax = [];
-    elseif (ishandle (ca) && isprop (ca, "__plotyy_axes__"))
-      ax = get (ca, "__plotyy_axes__");
-    else
-      ax = ca;
-    endif
-    if (length (ax) > 2)
-      for i = 3 : length (ax)
-        delete (ax (i));
-      endfor
-      ax = ax(1:2);
-    elseif (length (ax) == 1)
-      ax(2) = axes ();
-      set (ax(2), "nextplot", get (ax(1), "nextplot"));
-    elseif (isempty (ax))
-      ax(1) = axes ();
-      ax(2) = axes ();
-      ca = ax(2);
-    endif
-    if (nargin < 2)
-      varargin = {};
-    endif
-    oldh = ca;
-  endif
+  [hax, varargin] = __plt_get_axis_arg__ ("plotyy", varargin{:});
 
-  if (nargin < 4)
+  nargin = numel (varargin);
+  if (nargin < 4 || nargin > 6)
     print_usage ();
   endif
 
+  oldfig = [];
+  if (! isempty (hax))
+    oldfig = get (0, "currentfigure");
+  endif
   unwind_protect
-    [ax, h1, h2] = __plotyy__ (ax, varargin{:});
+    hax = newplot (hax);
+
+    ## FIXME: Second conditional test shouldn't be required.
+    ##        'cla reset' needs to delete user properties like __plotyy_axes__.
+    if (isprop (hax, "__plotyy_axes__")
+        && isaxes (get (hax, "__plotyy_axes__")) == [true true])
+      hax = get (hax, "__plotyy_axes__");
+    else
+      hax(2) = axes ("nextplot", get (hax(1), "nextplot"));
+    endif
+
+    [axtmp, h1tmp, h2tmp] = __plotyy__ (hax, varargin{:});
+
+    set (gcf, "currentaxes", hax(1));
+     
   unwind_protect_cleanup
-    ## Only change back to the old axis if we didn't delete it
-    if (isaxes (oldh))
-      axes (oldh);
+    if (! isempty (oldfig))
+      set (0, "currentfigure", oldfig);
     endif
   end_unwind_protect
 
   if (nargout > 0)
-    Ax = ax;
-    H1 = h1;
-    H2 = h2;
+    ax = axtmp;
+    h1 = h1tmp;
+    h2 = h2tmp;
   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
+function [ax, h1, h2] = __plotyy__ (ax, x1, y1, x2, y2, fun1 = @plot, fun2)
+
+  if (nargin < 7)
     fun2 = fun1;
   endif
 
   xlim = [min([x1(:); x2(:)]), max([x1(:); x2(:)])];
 
-  if (isaxes (ax(1)))
-    axes (ax(1));
-  else
-    ax(1) = axes ();
-  endif
-  newplot ();
+  axes (ax(1));
+
   h1 = feval (fun1, x1, y1);
 
-  set (ax(1), "ycolor", getcolor (h1(1)));
-  set (ax(1), "xlim", xlim);
-  set (ax(1), "color", "none");
-
-  cf = gcf ();
-  set (cf, "nextplot", "add");
+  set (ax(1), "color", "none", "ycolor", getcolor (h1(1)), "xlim", xlim);
 
-  if (isaxes (ax(2)))
-    axes (ax(2));
-  else
-    ax(2) = axes ();
-    set (ax(2), "nextplot", get (ax(1), "nextplot"));
-  endif
-  newplot ();
+  set (gcf (), "nextplot", "add");
+
+  axes (ax(2));
 
   colors = get (ax(1), "colororder");
   set (ax(2), "colororder", [colors(2:end,:); colors(1,:)]);
@@ -174,35 +127,38 @@
     set (ax, "activepositionproperty", "position");
   endif
 
-  ## Kluge, until __plt_get_axis_arg__ and newplot are reworked. 
-  set (ax(2), "nextplot", "replacechildren");
+  ## Don't replace axis which has colororder property already modified
+  if (strcmp (get (ax(1), "nextplot"), "replace"))
+    set (ax(2), "nextplot", "replacechildren");
+  endif
   h2 = feval (fun2, ax(2), x2, y2);
-  set (ax(2), "yaxislocation", "right");
-  set (ax(2), "ycolor", getcolor (h2(1)));
+
+  set (ax(2), "yaxislocation", "right", "color", "none",
+              "ycolor", getcolor (h2(1)), "box", "off", "xlim", xlim);
 
   if (strcmp (get(ax(1), "activepositionproperty"), "position"))
     set (ax(2), "position", get (ax(1), "position"));
   else
-    set (ax(2), "outerposition", get (ax(1), "outerposition"));
-    set (ax(2), "looseinset", get (ax(1), "looseinset"));
+    set (ax(2), {"outerposition", "looseinset"},
+                get (ax(1), {"outerposition", "looseinset"}));
   endif
 
-  set (ax(2), "xlim", xlim);
-  set (ax(2), "color", "none");
-  set (ax(2), "box", "off");
+  ## Restore nextplot value by copying value from axis #1
+  set (ax(2), "nextplot", get (ax(1), "nextplot"));
 
   ## Add invisible text objects that when destroyed,
   ## also remove the other axis
   t1 = text (0, 0, "", "parent", ax(1), "tag", "plotyy",
-             "handlevisibility", "off", "visible", "off",
+             "visible", "off", "handlevisibility", "off",
              "xliminclude", "off", "yliminclude", "off");
   t2 = text (0, 0, "", "parent", ax(2), "tag", "plotyy",
-             "handlevisibility", "off", "visible", "off",
+             "visible", "off", "handlevisibility", "off",
              "xliminclude", "off", "yliminclude", "off");
 
   set (t1, "deletefcn", {@deleteplotyy, ax(2), t2});
   set (t2, "deletefcn", {@deleteplotyy, ax(1), t1});
 
+  ## Add cross-listeners so a change in one axes' attributes updates the other.
   addlistener (ax(1), "position", {@update_position, ax(2)});
   addlistener (ax(2), "position", {@update_position, ax(1)});
   addlistener (ax(1), "outerposition", {@update_position, ax(2)});
@@ -235,6 +191,80 @@
   endif
 endfunction
 
+function deleteplotyy (h, ~, ax2, t2)
+  if (isaxes (ax2)
+      && (isempty (gcbf ()) || strcmp (get (gcbf (), "beingdeleted"), "off"))
+      && strcmp (get (ax2, "beingdeleted"), "off"))
+    set (t2, "deletefcn", []);
+    delete (ax2);
+  endif
+endfunction
+
+function update_nextplot (h, ~, ax2)
+  persistent recursion = false;
+  if (! recursion)
+    unwind_protect
+      recursion = true;
+      set (ax2, "nextplot", get (h, "nextplot"));
+    unwind_protect_cleanup
+      recursion = false;
+    end_unwind_protect
+  endif
+endfunction
+
+function update_position (h, ~, ax2)
+  persistent recursion = false;
+
+  ## Don't allow recursion
+  if (! recursion)
+    unwind_protect
+      recursion = true;
+      view = get (h, "view");
+      oldview = get (ax2, "view");
+      plotboxaspectratio = get (h, "plotboxaspectratio");
+      oldplotboxaspectratio = get (ax2, "plotboxaspectratio");
+      plotboxaspectratiomode = get (h, "plotboxaspectratiomode");
+      oldplotboxaspectratiomode = get (ax2, "plotboxaspectratiomode");
+
+      if (strcmp (get (h, "activepositionproperty"), "position"))
+        position = get (h, "position");
+        oldposition = get (ax2, "position");
+        if (! (isequal (position, oldposition) && isequal (view, oldview)))
+          set (ax2, "position", position, "view", view);
+        endif
+      else
+        outerposition = get (h, "outerposition");
+        oldouterposition = get (ax2, "outerposition");
+        if (! (isequal (outerposition, oldouterposition)
+               && isequal (view, oldview)))
+          set (ax2, "outerposition", outerposition, "view", view);
+        endif
+      endif
+
+      if (! (isequal (plotboxaspectratio, oldplotboxaspectratio)
+             && isequal (plotboxaspectratiomode, oldplotboxaspectratiomode)))
+        set (ax2, "plotboxaspectratio", plotboxaspectratio,
+                  "plotboxaspectratiomode", plotboxaspectratiomode);
+      endif
+    unwind_protect_cleanup
+      recursion = false;
+    end_unwind_protect
+  endif
+endfunction
+
+function color = getcolor (ax)
+  obj = get (ax);
+  if (isfield (obj, "color"))
+    color = obj.color;
+  elseif (isfield (obj, "facecolor") && ! ischar (obj.facecolor))
+    color = obj.facecolor;
+  elseif (isfield (obj, "edgecolor") && ! ischar (obj.edgecolor))
+    color = obj.edgecolor;
+  else
+    color = [0, 0, 0];
+  endif
+endfunction
+
 
 %!demo
 %! clf;
@@ -245,12 +275,11 @@
 %! xlabel ('X');
 %! ylabel (ax(1), 'Axis 1');
 %! ylabel (ax(2), 'Axis 2');
-%! axes (ax(1));
 %! text (0.5, 0.5, 'Left Axis', ...
-%!       'color', [0 0 1], 'horizontalalignment', 'center');
-%! axes (ax(2));
+%!       'color', [0 0 1], 'horizontalalignment', 'center', 'parent', ax(1));
 %! text (4.5, 80, 'Right Axis', ...
-%!       'color', [0 0.5 0], 'horizontalalignment', 'center');
+%!       'color', [0 0.5 0], 'horizontalalignment', 'center', 'parent', ax(2));
+%! title ({"plotyy() example"; "Left axis uses @plot, Right axis uses @semilogy"});
 
 %!demo
 %! clf;
@@ -267,14 +296,6 @@
 %! axis square;
 
 %!demo
-%! clf;
-%! x = linspace (-1, 1, 201);
-%! hax = plotyy (x, sin (pi*x), x, cos (pi*x));
-%! ylabel (hax(1), 'Blue on the Left');
-%! ylabel (hax(2), 'Green on the Right');
-%! xlabel ('xlabel');
-
-%!demo
 %! clf
 %! hold on
 %! t = (0:0.1:9);
@@ -284,81 +305,7 @@
 %! [~, h3, h4] = plotyy (t+1, x, t+1, y);
 %! set ([h3, h4], 'linestyle', '--');
 %! xlabel (hax(1), 'xlabel');
-%! title (hax(2), 'title');
+%! title (hax(2), 'Two plotyy graphs on same figure using "hold on"');
 %! ylabel (hax(1), 'Left axis is Blue');
 %! ylabel (hax(2), 'Right axis is Green');
 
-function deleteplotyy (h, d, ax2, t2)
-  if (isaxes (ax2)
-      && (isempty (gcbf ()) || strcmp (get (gcbf (), "beingdeleted"),"off"))
-      && strcmp (get (ax2, "beingdeleted"), "off"))
-    set (t2, "deletefcn", []);
-    delete (ax2);
-  endif
-endfunction
-
-function update_nextplot (h, d, ax2)
-  persistent recursion = false;
-  prop = "nextplot";
-  if (! recursion)
-    unwind_protect
-      recursion = true;
-      set (ax2, prop, get (h, prop));
-    unwind_protect_cleanup
-      recursion = false;
-    end_unwind_protect
-  endif
-endfunction
-
-function update_position (h, d, ax2)
-  persistent recursion = false;
-
-  ## Don't allow recursion
-  if (! recursion)
-    unwind_protect
-      recursion = true;
-      view = get (h, "view");
-      oldview = get (ax2, "view");
-      plotboxaspectratio = get (h, "plotboxaspectratio");
-      oldplotboxaspectratio = get (ax2, "plotboxaspectratio");
-      plotboxaspectratiomode = get (h, "plotboxaspectratiomode");
-      oldplotboxaspectratiomode = get (ax2, "plotboxaspectratiomode");
-
-      if (strcmp (get(h, "activepositionproperty"), "position"))
-        position = get (h, "position");
-        oldposition = get (ax2, "position");
-        if (! (isequal (position, oldposition) && isequal (view, oldview)))
-          set (ax2, "position", position, "view", view);
-        endif
-      else
-        outerposition = get (h, "outerposition");
-        oldouterposition = get (ax2, "outerposition");
-        if (! (isequal (outerposition, oldouterposition) && isequal (view, oldview)))
-          set (ax2, "outerposition", outerposition, "view", view);
-        endif
-      endif
-
-      if (! (isequal (plotboxaspectratio, oldplotboxaspectratio)
-             && isequal (plotboxaspectratiomode, oldplotboxaspectratiomode)))
-        set (ax2, "plotboxaspectratio", plotboxaspectratio);
-        set (ax2, "plotboxaspectratiomode", plotboxaspectratiomode);
-      endif
-    unwind_protect_cleanup
-      recursion = false;
-    end_unwind_protect
-  endif
-endfunction
-
-function color = getcolor (ax)
-  obj = get (ax);
-  if (isfield (obj, "color"))
-    color = obj.color;
-  elseif (isfield (obj, "facecolor") && ! ischar (obj.facecolor))
-    color = obj.facecolor;
-  elseif (isfield (obj, "edgecolor") && !  ischar (obj.edgecolor))
-    color = obj.edgecolor;
-  else
-    color = [0, 0, 0];
-  endif
-endfunction
-