Excel's Formula - sisman

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Part II: Using Functions in Your Formulas
Figure 8-15: This workbook demonstrates how to perform a lookup by using the closest match.
The array formula that follows identifies the closest match to the Target value in the Data range
and returns the names of the corresponding student in column A (that is, the column with an offset
of –1). The formula returns Leslie (with a matching value of 8,000, which is the one closest to
the Target value of 8,025).
{=INDIRECT(ADDRESS(ROW(Data)+MATCH(MIN(ABS(Target-Data)),
ABS(Target-Data),0)-1,COLUMN(Data)+ColOffset))}
If two values in the Data range are equidistant from the Target value, the formula uses the first
one in the list.
The value in ColOffset can be negative (for a column to the left of Data), positive (for a column to
the right of Data), or 0 (for the actual closest match value in the Data range).
To understand how this formula works, you need to understand the INDIRECT function. This function’s
first argument is a text string in the form of a cell reference (or a reference to a cell that
contains a text string). In this example, the text string is created by the ADDRESS function, which
accepts a row and column reference and returns a cell address.
Looking up a value using linear interpolation
Interpolation refers to the process of estimating a missing value by using existing values. For an
illustration of this concept, see Figure 8-16. Column D contains a list of values (named x) and column
E contains corresponding values (named y).