# Tips and Tricks

In many situations, a tip from us might help you set up an Array in just the right way for your situation. Below you will find a few tips and tricks that you may find useful.

- Here's how to move material from one element in an arrayed stock, back into another element in the same arrayed stock. Draw an outflow into a cloud, and then draw an inflow out of a cloud back into the same stock. Connect the two flows using a connector. Then, with Apply To All unchecked, you can define the inflow in terms of the outflow to move material from one element to the other. Figure 11-16 illustrates this concept.

Figure 11-16 Moving Material from One Element in an Arrayed Stock to Another

- If you find you want to use the sum of all the elements within an arrayed variable as an input into another variable, use the ARRAYSUM builtin to capture the sum of the elements.

- While creating and defining your two-dimensional arrayed variables, you might find it useful to keep a chart on paper (a matrix similar to what you saw in Figure 11-9). This will help keep a clear picture of the elements and cells you are modifying.

- Since Arrays reduce diagram clutter, the temptation is to overload the structure with more detail than you need. Avoid this temptation. Keep your models as simple as possible. As a practical matter, ask yourself if you'd use copy and paste to create the structure if arrays were not available. If the answer to this question is "no," the structure you are contemplating is probably too detailed.

- Before arraying variables, create and test the non-arrayed structure. Doing so will help you to manage the analytic complexity of working with arrays.

- Use short names when creating arrayed variables. Since the software will list the name plus the Dimension name(s) on input and output devices, shorter names will help you know what is assigned to what device.