--- a/scripts/ChangeLog	Thu Mar 15 02:36:10 2007 +0000
+++ b/scripts/ChangeLog	Thu Mar 15 14:11:51 2007 +0000
@@ -1,3 +1,15 @@
+2007-03-15  John W. Eaton  <jwe@octave.org>
+
+	* plot/__go_draw_axes__: Make have_newer_gnuplot persistent.
+	From Daniel J Sebald <daniel.sebald@ieee.org>.
+
+2007-03-15  Daniel J Sebald  <daniel.sebald@ieee.org>
+
+	* plot/__go_draw_axes__.m (do_linestyle_command): Fix marker types.
+
+	* control/base/rlocus.m: Add asymptotes to the plot.  Use wider
+	lines and larger markers.
+
 2007-03-14  John W. Eaton  <jwe@octave.org>
 
 	* plot/__axis_label__.m: Accept additional property-value pairs

--- a/scripts/control/base/rlocus.m	Thu Mar 15 02:36:10 2007 +0000
+++ b/scripts/control/base/rlocus.m	Thu Mar 15 14:11:51 2007 +0000
@@ -227,29 +227,64 @@
     if (! isempty (rlzer))
       nelts++;
     endif
+    # add asymptotes
+    n_A = length (olpol) - length (olzer);
+    if (n_A > 0)
+      nelts += n_A;
+    endif
     args = cell (3, nelts);
-    for kk=1:rows(rlpol)
-      args{1,kk} = real (rlpol (kk,:));
-      args{2,kk} = imag (rlpol (kk,:));
-      args{3,kk} = "b-";
+    kk = 0;
+    # asymptotes first
+    if (n_A > 0)
+      len_A = 2*max(abs(axlim));
+      sigma_A = (sum(olpol) - sum(olzer))/n_A;
+      for i_A=0:n_A-1
+        phi_A = pi*(2*i_A + 1)/n_A;
+        args{1,++kk} = [sigma_A sigma_A+len_A*cos(phi_A)];
+        args{2,kk} = [0 len_A*sin(phi_A)];
+        if (i_A == 1)
+          args{3,kk} = "k-;asymptotes;";
+        else
+          args{3,kk} = "k-";
+        endif
+      endfor
+    endif
+    # locus next
+    for ii=1:rows(rlpol)
+      args{1,++kk} = real (rlpol (ii,:));
+      args{2,kk} = imag (rlpol (ii,:));
+      if (ii == 1)
+        args{3,kk} = "b-;locus;";
+      else
+        args{3,kk} = "b-";
+      endif
     endfor
-    args{1,n_rlpol+1} = real(olpol);
-    args{2,n_rlpol+1} = imag(olpol);
-    args{3,n_rlpol+1} = "rx;open loop poles;";
-
+    # poles and zeros last
+    args{1,++kk} = real(olpol);
+    args{2,kk} = imag(olpol);
+    args{3,kk} = "rx;open loop poles;";
     if (! isempty(rlzer))
-      args{1,n_rlpol+2} = real(rlzer);
-      args{2,n_rlpol+2} = imag(rlzer);
-      args{3,n_rlpol+2} = "go;zeros;";
+      args{1,++kk} = real(rlzer);
+      args{2,kk} = imag(rlzer);
+      args{3,kk} = "go;zeros;";
     endif
 
-    plot (args{:})
+    set (gcf,"visible","off");
+    hplt = plot (args{:});
+    set (hplt(kk--), "markersize", 2);
+    if (! isempty(rlzer))
+      set(hplt(kk--), "markersize", 2);
+    endif
+    for ii=1:rows(rlpol)
+      set (hplt(kk--), "linewidth", 2);
+    endfor
     legend ("boxon", 2);
     grid ("on");
     axis (axlim);
     xlabel (sprintf ("Root locus from %s to %s, gain=[%f,%f]: Real axis",
 		     inname{1}, outname{1}, gvec(1), gvec(ngain)));
     ylabel ("Imag. axis");
+    set (gcf,"visible","on");
     rldata = [];
   endif
 endfunction

--- a/scripts/plot/__go_draw_axes__.m	Thu Mar 15 02:36:10 2007 +0000
+++ b/scripts/plot/__go_draw_axes__.m	Thu Mar 15 14:11:51 2007 +0000
@@ -32,7 +32,8 @@
 
     parent_figure_obj = get (axis_obj.parent);
 
-    have_newer_gnuplot = compare_versions (__gnuplot_version__ (), "4.0", ">");
+    persistent have_newer_gnuplot ...
+      = compare_versions (__gnuplot_version__ (), "4.0", ">");
 
     ## Set axis properties here?
 
@@ -765,7 +766,8 @@
 
 function style = do_linestyle_command (obj, idx, plot_stream)
 
-  have_newer_gnuplot = compare_versions (__gnuplot_version__ (), "4.0", ">");
+  persistent have_newer_gnuplot ...
+    = compare_versions (__gnuplot_version__ (), "4.0", ">");
 
   if (have_newer_gnuplot)
     fprintf (plot_stream, "set style line %d default;\n", idx);
@@ -812,11 +814,11 @@
       case "+"
 	pt = "1";
       case "o"
-	pt = "7";
+	pt = "6";
       case "*"
 	pt = "3";
       case "."
-	pt = "0";
+	pt = "7";
       case "x"
 	pt = "2";
       case {"square", "s"}
@@ -834,7 +836,7 @@
       case {"pentagram", "p"}
 	pt = "4";
       case {"hexagram", "h"}
-	pt = "6";
+	pt = "12";
       case "none"
 	pt = "";
       otherwise