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The '''Dynamic''' function can be used to express a recurrence along any index, where the value at one value depends on previous values, the same way it is used to express a recurrence along the <code>Time</code> index. For non-<code>Time</code> indexes, you must specify the index explicitly in square brackets following the function name.

In the following example, we are to acquire as much of item 1 as we can afford, but can only purchase an integer number of units. With whatever funds remain, we purchase as many integer units of item 2 as possible, as so on.

 Index Item := [1, 2, 3, 4]
 Unit_price := Table(Item)(5100, 1600, 800, 250)
 Budget := 20K
 Num_acquired := Floor(Funds_remaining/Unit_price)
 Spent := Num_acquired*Unit_price
 Funds_remaining := Dynamic[Item](budget, Self[Item - 1]-Spent[Item - 1])

The three variables, <code>Num_acquired, Spent</code>, and <code>Funds_remaining</code>, form a recurrence over the <code>Item</code> index. Evaluation proceeds starting with the dynamic context <code>Item = 1</code>. When <code>Num_acquired</code> is evaluated in this context, the <code>Unit_price</code> appearing in its definition evaluates to <code>Unit_price[Item = 1]</code>, since the use of a variable in a definition refers to its value sliced by the current dynamic context. Evaluation proceeds by evaluating each variable in the loop as <code>Item</code> is incremented and retaining the results for each value of <code>Item</code>:

[[File:Chapter17_15.png]]

==See Also==
* [[Dynamic]]()


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