function f = funcion_rectangular (t, T)
  nmuestras = length(t);
  f = zeros(nmuestras,1);
  for k=1:nmuestras
      n = floor(1 + (1/T)*(t(k)-T));
      t2 = t(k)-n*T;
      if t2 >=0 && t2 <= (T/2)
          f(k) = 1;
      else
          f(k) = 0;
      endif
  end    

endfunction