Local minimum possible. Constraints satisfied.

fmincon stopped because the size of the current search direction is less than
twice the default value of the step size tolerance and constraints are
satisfied to within the default value of the constraint tolerance.

<stopping criteria details>

Active inequalities (to within options.TolCon = 1e-06):
  lower      upper     ineqlin   ineqnonlin
                          1           
                          2           
                          5           

theta4 =

    0.0041    0.0010    0.1222    0.5864

Warning: The default trust-region-reflective algorithm does not solve problems with the
constraints you have specified. FMINCON will use the active-set algorithm instead. For
information on applicable algorithms, see Choosing the Algorithm in the documentation.
> In fmincon at 504
  In GARCH00 at 60
Warning: Your current settings will run a different algorithm (interior-point) in a future
release.