Excel 2000 in a Nutshell

Name

LOGEST

Synopsis

Use LOGEST to use the find the exponential curve that meets the specified data values and return an array of values that describe the curve. Since this function returns an array of values that describe the curve, it must be specified as an array formula. The function uses the equation y=b*m^x for a curve with one value specified for the Known_X's arguments or the equation y=(b*(m1^x1) * (m2^x2)* ...) for multiple values.

To Calculate

=LOGEST(Known_Y's, Known_X's, Const, Stats)

The Known_Y's argument is required for this function. All other arguments are optional.

Known_Y's

This array must contain a series of positive numbers. If the values in the array are in a single column, then the function interprets the values in each column of the Known_X's as a separate variable. If the values in the array are in a single row, then the function interprets the values in each row of the Known_X's array as a separate variable.

Known_X's

If this argument is omitted, it is assumed to be an array of values in the range of {1,2,3,...} that is the same size as the array specified by the Known_Y's argument.

Stats

Indicates a logical value of TRUE or FALSE that specifies whether additional regression statistics should be returned with the array. If the value is TRUE the function returns additional regression statistics.

Example

Figure 15-26 illustrates how to use LOGEST to find the values that describe an exponential curve.