ADDED   mttroot/mtt/lib/control/PPP/ppp_identify.m
Index: mttroot/mtt/lib/control/PPP/ppp_identify.m
==================================================================
--- /dev/null
+++ mttroot/mtt/lib/control/PPP/ppp_identify.m
@@ -0,0 +1,61 @@
+function [par,Par,Error,Y] = ppp_identify (system_name,u,y_0,par_names,par_0,extras)
+  ## ppp_identify: System identification for PPP
+  ## usage:  [par,Par,Error,Y] = ppp_identify(system_name,u,y_0,par_names,par_0,extras)
+  ##
+  ##  system_name     String containing system name
+  ##  u               System input (column vector, each row is u')
+  ##  y_0             Desired model output
+  ##  par_names       Column vector of (padded) strings - the adjustable
+  ##                  parameter names
+  ##  par_0           Initial parameter vector estimate
+  ##  extras (opt)    optimisation parameters
+  ##        .criterion convergence criterion
+  ##        .max_iterations limit to number of iterations
+  ##        .v  Initial Levenberg-Marquardt parameter
+
+  
+  if nargin<6
+    extras.criterion = 1e-5;
+    extras.max_iterations = 10;
+    extras.v = 1e-5;
+    extras.verbose = 0;
+  endif  
+
+  s_system_name = sprintf("s%s", system_name); # Name of sensitivity system
+
+  ## Set up parameters
+  sim = eval([s_system_name, "_simpar;"]); # Simulation parameter
+  sym = eval([s_system_name, "_sympar;"]); # Parameter names
+  x0  = eval([s_system_name, "_state(par_0);"]); # Initial state
+
+  ## Set up the free parameter list
+  free = [];
+  [n,m] = size(par_names);
+  for i = 1:n
+    p_name = deblank(par_names(i,:));
+    s_name = sprintf("%ss", p_name);
+    if struct_contains(sym, p_name)
+      i_p = eval(sprintf("sym.%s;", p_name));
+      if struct_contains(sym, s_name)
+	i_s = eval(sprintf("sym.%s;", s_name));
+	free_i = eval(sprintf("[%i,%i];", i_p, i_s));
+	free = [free; free_i];
+      else
+	printf("Sensitivity parameter %s does not exist: ignoring \
+	parameter %s\n", s_name, p_name);
+      endif
+    else
+      printf("Parameter %s does not exist: ignoring\n", p_name)
+    endif
+  endfor
+  
+  [par,Par,Error,Y] = ppp_optimise(s_system_name,x0,par_0,sim,u,y_0,free,extras);
+
+endfunction
+
+
+
+
+
+
+