# Dynamic initial values

A dynamic definition of var usually includes the expression Self[Time - k] or var[Time - k], where k is the number of time periods to subtract from the current Time value. It is typically the case that at least 1 initial value is supplied.

As an example, when k in [Time - k] is greater than 1, suppose your car insurance policy depends on the premium you paid two years ago. To calculate your payments in 1992, you must refer to the amount paid in 1990. A dynamic variable representing such a rate for insurance needs two initial values for Time, such as:

Variable Insurance :=
Dynamic(600, 700, Insurance[Time - 2]*1.05) →