Microsoft KB Archive/61294

= Microsoft Knowledge Base =

Excel: Using the TREND Funtion for Interpolation
Last reviewed: September 23, 1997

Article ID: Q61294

2.20 MACINTOSH kbother

SUMMARY
Interpolation finds the y value that corresponds with a known x value, based on a group of known x and y values.

To perform interpolation in Microsoft Excel, use the TREND function.

MORE INFORMATION
For example:

|  A   |   B   | --|---|---|  1 |  Y's  |  X's  | 2 | .2   |   1   |   3 |  .5   |   4   | To interpolate the y value that corresponds with a known x of 3, based on the above known y values and known x values, use the following formula:

=TREND(A2:A3,B2:B3,{3}) This formula will return .40.

The braces (&quot;{&quot; and &quot;}&quot;) are required around any arguments that are not cell references, because they are values that represent an array.

For example, to perform the same interpolation without using cell references, use the following formula:

=TREND({.2,.5},{1,4},{3}) Note: The TREND function can also be used to interpolate values outside the given range of values.

For more information on the TREND function, see page 86 of the &quot;Microsoft Excel Functions and Macros&quot; version 2.2 manual.