﻿ TrendLineLogarithmic(String,Series,Double,Int32,Int32) Method
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 dotnetCHARTING Namespace > ForecastEngine Class > TrendLineLogarithmic Method : TrendLineLogarithmic(String,Series,Double,Int32,Int32) Method

seriesName
The name of the series which will be displayed on the chart, i.e. its label.
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.
Find the best fit for the function f(x) = a + b * ln(x).

# Syntax

Visual Basic (Declaration)
```Public Overloads Shared Function TrendLineLogarithmic( _
ByVal seriesName As String, _
ByVal s As Series, _
ByVal step As Double, _
ByVal forward As Integer, _
ByVal backward As Integer _
) As Series```
Visual Basic (Usage)Copy Code
``````Dim seriesName As String
Dim s As Series
Dim step As Double
Dim forward As Integer
Dim backward As Integer
Dim value As Series

value = ForecastEngine.TrendLineLogarithmic(seriesName, s, step, forward, backward)``````
C#
```public static Series TrendLineLogarithmic(
string seriesName,
Series s,
double step,
int forward,
int backward
)```

#### Parameters

seriesName
The name of the series which will be displayed on the chart, i.e. its label.
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.