function [GTt] = GT(t,P,Q,eq,n);
        
% calculate: GT: \R^{eq} \to S^{n*n+1}
% input: t... vector:  (n*n + 1)*( n*n + 1)
%        n ... dimension of matices A, B, C    
% 21.11.'01 rsotirov
% call: [GTt] = GT(t,P,Q,eq,n);

  
if eq == 0, GTt = zeros(n*n+1); 
else  
   GTt = zeros(n*n+1);
   GTt((n*n+1)*(Q-1)+P)=t;
end;

%GTt=tril(GTt);
GTt = ( GTt + GTt' )/2;


