function [RC] = ltirc(A,B)
%
% author: Nasser M. Abbasi  
% change history
% -----------------------------------------------
% date      reason
% 3-2-92    intial
%
% -----------------------------------------------
% 
% specification: construct the controllability matrix
% Rc for a time-invariant dynamic equation
%
% paramters:
% A  : is an IN argument , the nXn matrix  of state quation
% B  : is an IN argument , the B matrix of the state equation
% Rc : is an OUT parameter, the The controllabity matrix
%
% implicit input:
% none
%
% implicit output :
% none
%
%------------------------------------------------

if(nargin ~=2)
 error('number of input arguments must be 2, the A and B matrices');
end

[row,col]= size(A);

if(row ~= col)
  error('the matrix A supplied must be a square matrix');
end

n= max(size(A));
[row,col]= size(B);

%
% build the first element of Rc
%
t(1:row,1:col)= B;

cur_row= row;
cur_col= col;
%
% Now loop from 1 to n-1 to build the rest of Rc 
%
for i=1:n-1
    a= A^i * B;
    [row,col]= size(a);
    t(1:cur_row, cur_col+1:cur_col+col)= a;
    cur_col= cur_col+col;
end
RC= t;