ADDED   mttroot/mtt/bin/trans/m/sm2ir.m
Index: mttroot/mtt/bin/trans/m/sm2ir.m
==================================================================
--- /dev/null
+++ mttroot/mtt/bin/trans/m/sm2ir.m
@@ -0,0 +1,63 @@
+function [Y,X] = sm2ir(A,B,C,D,T,u0,x0);
+% [Y,X] = sm2ir(A,B,C,D,T,u0,x0);
+% Constrained-state matrix to impulse response.
+% A,B,C,D,E - (constrained) state matrices
+% T vector of time points
+% u0 input gain vector: u = u0*unit step.
+
+
+% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% %% Version control history
+% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% %% $Id$
+% %% $Log$
+% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+[Ny,Nu] = size(D);
+[Ny,Nx] = size(C);
+
+if max(max(abs(D)))~=0
+  mtt_info('D matrix non-zero - ignoring');
+end;
+
+if nargin<6
+  u0 = zeros(Nu,1);
+  u0(1) = 1;
+end;
+
+if nargin<7
+  x0 = zeros(Nx,1);
+end;
+
+[N,M] = size(T);
+if M>N
+  T = T';
+  N = M;
+end;
+
+
+
+one = eye(Nx);
+
+Y = zeros(N,Ny);
+X = zeros(N,Nx);
+i = 0;
+for t = T'
+  i=i+1;
+  if Nx>0
+    expAt = expm(A*t);
+    x = expAt*(B*u0+x0);
+    X(i,:) = x';
+    if Ny>0
+      y = C*x;
+      Y(i,:) = y';
+    end;
+  end;
+end;
+
+
+
+
+
+