Find the best fit for the function f(x) = a + b * ln(x).

# Syntax

#### Parameters

*s*
- A statistical series.
*step*
- The distance in the x-coordinate between two adjacent extended points.
Please note that this also corresponds to the distance in the x-coordinate between the
highest and lowest original data point and the first (above or below) additional evaluation
point.
*forward*
- The number of additional evaluation points which are evaluated above
the x-coordinates of the original given data set.
*backward*
- The number of additional evaluation points which are evaluated below
the x-coordinates of the original given data set.

#### Return Value

A series where the k-th element of the array represents of k-th point
(i.e. { x_k, y_k }) of the total set over which the fitted function is evaluated.
The total set over which the fitted function is evaluated consists of the `backward' points,
original data set points and the `forward' points.

**Remark:** This methods corresponds in functionality to the method of the same
name within Microsoft Excel.

# See Also