# Perturbation

### From Glossary

An imprecise term that means changing some parameter value (or function) and seeing what effect this has on the solution. This embodies continuity and differentiability properties of the optimal responses: objective value, policy set, and perhaps dual values too. This is what is sometimes called *marginal analysis* of solutions, and changes are limited to some neighborhood of the initial values. Some use *perturbation function* to mean the optimal objective value, even for large changes in the parameters, as in parametric programming.