PROC UCM uses the nonlinear optimization (NLO) subsystem to perform the nonlinear optimization of the likelihood function during the estimation of model parameters. You can use the NLOPTIONS statement to control different aspects of this optimization process. For most problems the default settings of the optimization process are adequate. However, in some cases it might be useful to change the optimization technique or to change the maximum number of iterations. This can be done by using the TECH= and MAXITER= options in the NLOPTIONS statement as follows:
nloptions tech=dbldog maxiter=200;
This sets the maximum number of iterations to 200 and changes the optimization technique to DBLDOG rather than the default technique, TRUREG, used in PROC UCM. A discussion of the full range of options that can be used with the NLOPTIONS statement is given in ChapterĀ 6: Nonlinear Optimization Methods. In PROC UCM all these options are available except the options related to the printing of the optimization history. In this version of PROC UCM all the printed output from the NLO subsystem is suppressed.