Array Functions are Past Times

Long ago, Excel was not as clever and advanced as today, but the so-called array functions have been around for a long time. However, most people do not know about them, and do not understand them. This is perhaps because of the very different nature of the formulas or the strange way of activating them (CTRL-SHIFT ENTER instead of just ENTER).

Excel Guideline 09: Array Functions are Past Times :: PerfectXL

What is an Array Function?

An array formula is, simply stated, a formula that very cleverly combines multiple calculations as an array. For example, SUM (B2: B10 * C2: C10) is the sum of (B2 * C2) + (B3 * C3) etcetera. The result of the array function will only be shown after you double click the cell with the formula to select it and then press CTRL+SHIFT+ENTER.

Excel Guideline 09: Array Functions Are Past Times - Example :: PerfectXL

The Danger of using Array Functions

It’s better not to use array functions unless it’s truly necessary because, your spreadsheet might later be maintained by someone who does not understand array functions very well. They might change something in the array formula without knowing that it is an array…so they won’t press CTRL-Shift-Enter and your nice functionality will be completely lost and gone. Or they might make a change in the input column of the array without realizing the consequences and everything goes wrong.

Alternatives

Fortunately, there are alternative methods to get to the same results. For example, use an extra column for an intermediate calculation (B2 * C2, as in the example). There is rarely a lack of space since Excel 2010. You can also choose to use new smart built-in Excel features like SUMIFS, MAXIF, and AVERAGEIFS, which can also be combined to attain similar results as those that come with an Array function.

Excel Guideline 09: Array Functions Are Past Times - Example :: PerfectXL

When to Use Array Functions

When is it safe to use array functions? If you’re sure nobody else ever has to worry about it and/or you are the only user of the spreadsheet (but how do you know?). They can also be used in situations where the spreadsheet’s memory usage needs to be kept very limited, because array formulas are memory efficient.

How does PerfectXL help?

If you analyze your spreadsheet with PerfectXL and go to the risk overview, you will see a section called, “complex formulas.” This shows formulas which are complex and therefore difficult to maintain and understand, and potentially risky for future users. In this category you are able to see whether or not your spreadsheet contains array functions, and where those array functions are.

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