  function y = SL_A(A, mode, m, n, x, I, dim)
  % Ivan Damnjanovic 2009
  % This is auxilary function to allow implicit matrices from SPARCO 
  % to be used with SparsLab solvers
  
  global SMALL
    if (mode == 1)
    
            u = zeros(dim, 1);
            u(I) = x;
            y = A(u,1);
           
        elseif (mode == 2)
    
            x2 = A(x,2);
            y = x2(I);
           
     end
       
    end