One of Excel’s most interesting (and most powerful) features is its ability to work with arrays in formulas. When you understand this concept, you’ll be able to create elegant formulas that appear to perform spreadsheet magic.
This chapter introduces the concept of arrays and is required reading for anyone who wants to become a master of Excel formulas. Chapter 18 continues with lots of useful examples.
If you do any computer programming, you’ve probably been exposed to the concept of an array. An array is simply a collection of items operated on collectively or individually. In Excel, an array can be one dimensional or two dimensional. These dimensions correspond to rows and columns. For example, a one-dimensional array can be stored in a range that consists of one row (a horizontal array) or one column (a vertical array). A two-dimensional array can be stored in a rectangular range of cells. Excel doesn’t support three-dimensional arrays (but its VBA programming language does).
As you’ll see, arrays need not be stored in cells. You can also work with arrays that exist only in Excel’s memory. You can then use an array ...