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+# Copyright (C) 1996 A. Scottedward Hodel 
+#
+# 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 2, 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, write to the Free 
+# Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. 
+ 
+page_screen_output = 1;
+opt = 0;
+QUITOPT = 7;
+while (opt != QUITOPT)
+  opt = menu("Marsyas interface update demo:", ...
+	"run Marsyas on the magnetically suspended ball example", ...
+        "load continuous time marsyas example system", ...
+	"load discrete-time marsyas example system", ...
+	"bode plot of loaded system (MIMO)", ...
+        "bode plot of loaded system (SISO)", ...
+	"Design example", ...
+	"Quit");
+
+  if(opt == 1)
+    cmd = "system(""marsyas mag1d.mar"")";
+    run_cmd
+    cmd = "system(""marplot -i"")";
+    run_cmd
+  elseif(opt == 2)
+    cmd = "ballsys = margetsys();";
+    run_cmd;
+    cmd = "sysout(ballsys);"
+    run_cmd
+  elseif(opt == 3)
+    cmd = "ballsys = margetsys(""disc"");";
+    run_cmd
+    cmd = "sysout(ballsys);"
+    run_cmd
+  elseif(opt == 4)
+    cmd = "bode(ballsys);";
+    run_cmd
+  elseif(opt == 5)
+    cmd = "bode(ballsys,[],1,1);";
+    run_cmd
+  elseif(opt == 6)
+    if(!exist("ballsys"))
+      warning("You didn't load a system yet (option 2 or 3)");
+    else
+      disp("Design LQG controller");
+      cmd = "sysout(ballsys)";
+      run_cmd
+      disp("add noise inputs to system...")
+      if(ballsys.n)
+        disp("continuous system:")
+        cmd = "ballsys1 = sysappend(ballsys,eye(ballsys.n));";
+      else
+        disp("discrete system:")
+        cmd = "ballsys1 = sysappend(ballsys,eye(ballsys.nz));";
+      endif
+      run_cmd
+      cmd = "sysout(ballsys1)";
+      run_cmd
+      disp("Notice the two additional inputs, u_2, and u_3.  These are the ");
+      disp("""entry points"" for the gaussian noise disturbance.");
+      disp(" ");
+      disp("We'll design the controller to use only position feedback:")
+      cmd = "ballsys1=sysprune(ballsys1,1,[]);";
+      run_cmd
+      cmd = "sysout(ballsys1)";
+      run_cmd
+      disp("Now design an LQG controller: Sigw: input noise")
+      Sigw = eye(2)
+      disp("Now design an LQG controller: Sigv: measurement noise")
+      Sigv = eye(rows(ballsys1.c))
+      disp("State and input penalties:")
+      Q = eye(2)
+      R = 1
+      disp("Controlled input is input 1");
+      cmd="Ksys = lqg(ballsys1,Sigw,Sigv,Q,R,1);";
+      run_cmd
+      disp("sysout(Ksys);");
+      sysout(Ksys);
+      
+      disp("marsyas conversion: output in scalar form:")
+      cmd = "maroutsys(Ksys, ""ball_controller"",""scalar"");";
+      run_cmd
+      disp("here's the output file:")
+      prompt
+      system("more ball_controller.mar");
+      
+      disp("marsyas conversion: output in state space form: (default option;")
+      disp("the ""ss"" in the command below is not needed)")
+      cmd = "maroutsys(Ksys, ""ball_controller_ss"",""ss"");";
+      run_cmd
+      disp("here's the output file:")
+      prompt
+      system("more ball_controller_ss.mar");
+      
+      disp("marsyas conversion: output in transfer function form:")
+      cmd = "maroutsys(Ksys, ""ball_controller_tf"",""tf"")"
+      run_cmd
+      disp("here's the output file:")
+      prompt
+      system("more ball_controller_tf.mar");
+  
+    endif
+  endif
+endwhile