I already followed your advice. The problem is if I use the header/footer of the NK_baseline_steady_state.m file in the Dynare examples folder I get the following error:
Undefined function or variable 'c1welfss'.
Error in nonlinearomega_steadystate (line 26)
c1welf = c1welfss;
Error in evaluate_steady_state_file (line 49)
[ys,check] = h_steadystate(ys_init, exo_ss);
Error in evaluate_steady_state (line 58)
[ys,params,info] = evaluate_steady_state_file(ys_init,exo_ss,M, ...
Error in steady_ (line 54)
[steady_state,params,info] =
evaluate_steady_state(oo_.steady_state,M_,options_,oo_,~options_.steadystate.nocheck);
Error in steady (line 81)
[steady_state,M_.params,info] = steady_(M_,options_,oo_);
Error in nonlinearomega (line 3094)
steady;
Error in dynare (line 180)
evalin('base',fname) ;
And, unfortunately, I have no idea about what should be done.