It seems that made some mistake in my code. I tried to use the following setting, where Ac is the technology level

Ac=Ac(-1)+gr;

gr=0.95*gr(-1)+e1;

where e1 is i.i.d.

But I got the following error message

??? Index exceeds matrix dimensions.

Error in ==> simult at 19

chol_S = chol(Sigma_e_(i_exo_var,i_exo_var));

Error in ==> stoch_simul at 85

y_ = simult(repmat(dr_.ys,1,ykmin_),dr_);

Error in ==> TSJH_feb5_gr at 259

info=stoch_simul(var_list_);

Error in ==> dynare at 26

evalin(‘base’,fname) ;

I check the rank of Sigma_e_ and it turns out to be 0.