"? Input argument "params" is undefined" error

when run attached file, i see following error:

??? Input argument “params” is undefined.

Error in ==> model_static at 15
rhs =y(15)*params(4)+params(1)+x(1);

Error in ==> solve1 at 55
fvec = feval(func,x,varargin{:});

Error in ==> dynare_solve at 73
[x,info]=solve1(func,x,j1(r(i):r(i+1)-1),j2(r(i):r(i+1)-1),jacobian_flag,varargin{:});

Error in ==> evaluate_steady_state at 66
[ys,check] = dynare_solve([M.fname ‘_static’],…

Error in ==> steady_ at 54
[steady_state,params,info] =
evaluate_steady_state(oo_.steady_state,M_,options_,oo_,~options_.steadystate.nocheck);
Error in ==> steady at 81
[steady_state,M_.params,info] = steady_(M_,options_,oo_);

Error in ==> model at 224
steady;

Error in ==> dynare at 120
evalin(‘base’,fname) ;

please help if you can. are this a bug ?

Your FOCs are wrong. It should be exp(z) instead of z as you defined z to be a mean 0 process. Otherwise, you will have 0 output and consumption in steady state.

your shock process must be in log form,
the way you have defined it, it means in steady state everything is zero. while shocks must be equal to one in SS.


model;

log(z)=rho*log(z(-1))+e;
end;

initval;

z=1;
end;