Index: mttroot/mtt/lib/control/PPP/ppp_ex15.m
==================================================================
--- mttroot/mtt/lib/control/PPP/ppp_ex15.m
+++ mttroot/mtt/lib/control/PPP/ppp_ex15.m
@@ -40,11 +40,12 @@
 
   ## Closed-loop intermittent solution
   Delta_ol = 0.5		# Intermittent time
 
   disp("Intermittent control simulation");
-  [T,y,u] = ppp_qp_sim (A,B,C,D,A_u,A_w,t,Q, \
+  R=1;P=0;
+  [T,y,u] = ppp_qp_sim (A,B,C,D,A_u,A_w,t,Q,R,P, \
 			  [],[],[],[], \
 			  [],[],[],[],W,x_0,Delta_ol);
 size(T)
   ## Exact closed-loop
   disp("Exact closed-loop");

Index: mttroot/mtt/lib/control/PPP/ppp_inflate.m
==================================================================
--- mttroot/mtt/lib/control/PPP/ppp_inflate.m
+++ mttroot/mtt/lib/control/PPP/ppp_inflate.m
@@ -13,11 +13,11 @@
     error("A_v must have at least as many rows as columns");
   endif
   
   n = N/M;			# Number of matrix elements in A_v
 
-  if round(n)<>n
+  if round(n)!=n
     error("A_v must be a column vector of square matrices");
   endif
   
   A_m = [];
   for i = 1:n

Index: mttroot/mtt/lib/control/PPP/ppp_lin.m
==================================================================
--- mttroot/mtt/lib/control/PPP/ppp_lin.m
+++ mttroot/mtt/lib/control/PPP/ppp_lin.m
@@ -167,11 +167,12 @@
     J_xx = J_xx + (QQ .* y_x(:,i:n_y:n_yx)') * y_x(:,i:n_y:n_yx);
   endfor
 
   ## Input weighting (scalar for the moment)
   if (n_u>1)
-    warning("Sorry, cant do n_u>1 just now");
+    warning("Sorry, cant do n_u>1 just now: exiting");
+    return
   endif
 
   ## Scale R
   R = R*dt;			# Scale to give correct units
   for i = 1:m_t

Index: mttroot/mtt/lib/control/PPP/ppp_lin_quad.m
==================================================================
--- mttroot/mtt/lib/control/PPP/ppp_lin_quad.m
+++ mttroot/mtt/lib/control/PPP/ppp_lin_quad.m
@@ -1,16 +1,23 @@
 function [k_x,k_w,K_x,K_w,Us0,J_uu,J_ux,J_uw,J_xx,J_xw,J_ww,A_u] = \
-      ppp_lin_quad (A,B,C,D,tau,Q,R)
+      ppp_lin_quad (A,B,C,D,tau,Q,R,A_e)
 
   ## usage:[k_x,k_w,K_x,K_w,Us0,J_uu,J_ux,J_uw,J_xx,J_xw,J_ww,A_u] =
-  ## ppp_lin_quad (A,B,C,D,tau,Q,R)
+  ## ppp_lin_quad (A,B,C,D,tau,Q,R[,A_e])
   ##
   ## 
 
   ## Steady-state Linear Quadratic solution
   ## using Algebraic Riccati equation (ARE)
+
+  if nargin<8
+    A_e = [];
+  endif
+  
   [P,A_u,A_w] = ppp_are (A,B,C,D,Q,R);
+
+  A_u = ppp_aug(A_u,A_e);
 
   ## PPP solution
   [k_x,k_w,K_x,K_w,Us0,J_uu,J_ux,J_uw,J_xx,J_xw,J_ww] = \
       ppp_lin(A,B,C,D,A_u,A_w,tau,Q,R,P);
 

Index: mttroot/mtt/lib/control/PPP/ppp_open2closed.m
==================================================================
--- mttroot/mtt/lib/control/PPP/ppp_open2closed.m
+++ mttroot/mtt/lib/control/PPP/ppp_open2closed.m
@@ -16,11 +16,11 @@
 
   ## Check sizes
   n_o = is_square(A_u);
   n_c = is_square(A_c);
 
-  if (n_o==0)||(n_c==0)||(n_o<>n_c)
+  if (n_o==0)||(n_c==0)||(n_o!=n_c)
     error("A_u and A_c must be square and of the same dimension");
   endif
 
   [n_u,n_x] = size(k_x);
 

Index: mttroot/mtt/lib/control/PPP/ppp_qp_sim.m
==================================================================
--- mttroot/mtt/lib/control/PPP/ppp_qp_sim.m
+++ mttroot/mtt/lib/control/PPP/ppp_qp_sim.m
@@ -62,12 +62,12 @@
   else
     T_ol = [0,dt];
     Delta_ol = dt;
   endif
   t_last = t(length(t));
-  T_cl = 0:Delta_ol:t_last-Delta_ol; # Closed-loop time vector
-  T = 0:dt:t_last;		# Overall time vector
+  T_cl = 0:Delta_ol:2*t_last-Delta_ol; # Closed-loop time vector
+  T = 0:dt:2*t_last;		# Overall time vector
  
   ## Lengths thereof
   n_Tcl = length(T_cl);
   n_ol = length(T_ol);
   n_T = length(T);
@@ -102,11 +102,11 @@
   J = [];
   tick= time;
 
   ## disp("Simulating ...");
   for t=T_cl			# Outer loop at Delta_ol
-
+    printf("%g\r",t);
     ##disp(sprintf("Time %g", t));
     ## Output constraints
     [Gamma_y,gamma_y] = ppp_output_constraints  (A,B,C,D,x,A_u,Tau_y,Min_y,Max_y,Order_y);
     
     ## Composite constraints 

Index: mttroot/mtt/lib/control/PPP/ppp_ystar.m
==================================================================
--- mttroot/mtt/lib/control/PPP/ppp_ystar.m
+++ mttroot/mtt/lib/control/PPP/ppp_ystar.m
@@ -22,12 +22,18 @@
   ## AA          The composite system matrix
   
   ## Copyright (C) 1999 by Peter J. Gawthrop
   ## 	$Id$	
 
-
-  [n_x,n_u,n_y] = abcddim(A,B,C,D); # System dimensions
+  if (size(A)>0)
+    [n_x,n_u,n_y] = abcddim(A,B,C,D); # System dimensions
+  else
+    n_x = 0;
+    n_y = 0;
+    n_u = 0;
+  endif
+  
   no_system = n_x==0;
 
   [n,m] = size(A_u);		# Size of composite A_u matrix
   square = (n==m);		# Is A_u square?
   n_U = m;			# functions per input
@@ -115,15 +121,20 @@
   ## Compute the star variables
   for t=tau
     xxt = expm(AA*t)*xx_0;	# Composite state
     xst = xxt(1:n_x);		# x star
     xut = xxt(n_x+1:n_xx);	# x star
-    yst = C*xst;		# y star
+    if length(C)>0
+      yst = C*xst;		# y star
+    else
+      yst = [];
+    endif
+    
     ust = Utilde*xut;		# u star
 
     xs = [xs xst];		# x star
     xu = [xu xut];		# x star
     ys = [ys yst];		# y star
     us = [us ust];		# u star
   endfor
 
 endfunction