Page 386 - Excel 2007 Bible

23_044039 ch18.qxp 11/21/06 11:09 AM Page 343
Performing Magic with Array Formulas
Determining the closest value in a range
The array formula that follows returns the value in a range named Data that is closest to another value
(named Target):
{=INDEX(Data,MATCH(SMALL(ABS(Target-Data),1),ABS(Target-Data),0))}
If two values in the Data range are equidistant from the Target value, the formula returns the first one in the
list. Figure 18.7 shows an example of this formula. In this case, the Target value is 45. The array formula in
cell D5 returns 48 — the value closest to 45.
FIGURE 18.7
An array formula returns the closest match.

Returning the last value in a column 18
Suppose that you have a worksheet that you update frequently by adding new data to columns. You may
need a way to reference the last value in column A (the value most recently entered). If column A contains
no empty cells, the solution is relatively simple and doesn’t require an array formula:
=OFFSET(A1,COUNTA(A:A)-1,0)
This formula uses the COUNTA function to count the number of nonempty cells in column A. This value
(minus 1) is used as the second argument for the OFFSET function. For example, if the last value is in row
100, COUNTA returns 100. The OFFSET function returns the value in the cell 99 rows down from cell A1 in
the same column.
If column A has one or more empty cells interspersed, which is frequently the case, the preceding formula
won’t work because the COUNTA function doesn’t count the empty cells.

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