Excel's Formula - sisman

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Part IV: Array Formulas
In this case, you can use Excel’s SUMPRODUCT function to obtain the same result without
using an array formula:
=SUMPRODUCT(B2:B7,C2:C7)
As you’ll see, however, array formulas allow many other types of calculations that are
otherwise not possible.
Creating an array constant
The examples in the previous section used arrays stored in worksheet ranges. The examples in
this section demonstrate an important concept: An array does not have to be stored in a range of
cells. This type of array, which is stored in memory, is referred to as an array constant.
You create an array constant by listing its items and surrounding them with curly brackets. Here’s
an example of a five-item horizontal array constant:
{1,0,1,0,1}
The following formula uses the SUM function, with the preceding array constant as its argument.
The formula returns the sum of the values in the array (which is 3). Notice that this formula uses
an array, but it is not an array formula. Therefore, you do not use Ctrl+Shift+Enter to enter the
formula.
=SUM({1,0,1,0,1})
When you specify an array directly (as shown previously), you must provide the curly
brackets around the array elements. When you enter an array formula, on the other
hand, you do not supply the curly brackets.
At this point, you probably don’t see any advantage to using an array constant. The formula that
follows, for example, returns the same result as the previous formula:
=SUM(1,0,1,0,1)
Keep reading, and the advantages will become apparent.
Following is a formula that uses two array constants:
=SUM({1,2,3,4}*{5,6,7,8})