# 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) →`

## See Also

Comments

Enable comment auto-refresher