# Shocks in a model written in non-linear form

When writing a model in its non-linear form, one needs to make sure that the steady state is entirely consistent with the model, such that in each equation the left hand side=right hand side. i.e your residuals are zero. If that is not the case, then the model can’t find a steady state since the residual errors are too large.

My question is related to how one accounts for the above when one considers a positive steady state value of a shock variable, but which has a zero standard deviation. For instance, one can have government spending in a model, which is driven by an AR1 shock process. If that shock is zero, there is still a positive steady state government spending. How does one make sure that the nonlinear equations are consistent in this case?

For instance, assume I have a resource constraint given by:

`exp(c)+exp(g)=exp(y)`
where
`g=rho*g(-1)+epsilon`
Assume epsilon is 0. The equation then becomes
`exp(c)+1=exp(y)`, but in steady state we still have
`c*+g*=y*` where `x*` is the steady state value of each variable.

I can multiply `exp(g)` by `g*`, but then does that mean that I would have to write the non logged steady state value for g?

Have a look at