Apple iWork '09 - Manual (Page 214)

INDEX
The INDEX function returns the value in the cell located at the intersection of the
specified row and column within a range of cells or an array.
INDEX(range, row-index, column-index, area-index)
 range: A range of cells. range may contain values of any type. range is either a single
range or more than one range separated by commas and enclosed in an additional
set of parentheses. For example, ((B1:B5, C10:C12)).
 row-index: The row number of the value to be returned. row-index is a number
value and must be greater than or equal to 0 and less than or equal to the number
of rows in range.
 column-index: An optional value specifying the column number of the value to be
returned. column-index is a number value and must be greater than or equal to 0
and less than or equal to the number of columns in range.
 area-index: An optional value specifying the area number of the value to be
returned. area-index is a number value and must be greater than or equal to 1 and
less than or equal to the number of areas in range. If omitted, 1 is used.
Usage Notes
INDEX can return the value at the specified intersection of a two-dimensional range Â
of values. For example, assume that cells B2:E7 contain the values. =INDEX(B2:D7, 2,
3) returns the value found at the intersection of the second row and third column
(the value in cell D3).
More than one area can be specified by enclosing the ranges in an additional pair
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of parentheses. For example, =INDEX((B2:D5,B7:D10), 2, 3, 2) returns the value at the
intersection of the second column and the third row in the second area (the value in
cell D8).
INDEX can return a one-row or one-column array for another function. In this
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form, either row-index or column-index is required, but the other argument may be
omitted. For example =SUM(INDEX(B2:D5, , 3)) returns the sum of the values in the
third column (cells D2 through D5). Similarly, =AVERAGE(INDEX(B2:D5, 2)) returns the
average of the values in the second row (cells B3 through D3).
INDEX can return (or “read”) the value from an array returned by an array
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function (a function that returns an array of values, rather than a single value).
The FREQUENCY function returns an array of values, based on specified intervals.
=INDEX(FREQUENCY($A$1:$F$5, $B$8:$E$8), 1) would turn the first value in the array
returned by the given FREQUENCY function. Similarly =INDEX(FREQUENCY($A$1:$F$5,
$B$8:$E$8), 5) would return the fifth value in the array.
The location in the range or array is specified by indicating the number of rows
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down and the number of columns to the right in relation to the cell in the upper-
left corner of the range or array.
214 Chapter 9 Reference Functions