# Class "logarithm"

### Description

Logartithmic transformation of an argument is a transformation defined by the function

*f(parameter,a,b)= ln(a*prarameter)*b ~~~~a*parameter>0*

*0 ~~~~a*parameter<=0*

### Objects from the Class

Objects can be created by calls to the constructor
`logarithm(parameters,a,b,transformationId)`

### Slots

`.Data`

:Object of class

`"function"`

~~`a`

:Object of class

`"numeric"`

-non zero multiplicative constant`b`

:Object of class

`"numeric"`

-non zero multiplicative constant`parameters`

:Object of class

`"transformation"`

-flow parameters to be transformed`transformationId`

:Object of class

`"character"`

-unique ID to reference the transformation

### Extends

Class `"singleParameterTransform"`

, directly.
Class `"transform"`

, by class "singleParameterTransform", distance 2.
Class `"transformation"`

, by class "singleParameterTransform", distance 3.
Class `"characterOrTransformation"`

, by class "singleParameterTransform", distance 4.

### Methods

No methods defined with class "logarithm" in the signature.

### Note

The logarithm transformation object can be evaluated using the eval method by passing the data frame as an argument.The transformed parameters are returned as a matrix with a single column. (See example below)

### Author(s)

Gopalakrishnan N, F.Hahne

### References

Gating-ML Candidate Recommendation for Gating Description in Flow Cytometry V 1.5

### See Also

exponential,quadratic

### Examples

1 2 3 4 | ```
dat <- read.FCS(system.file("extdata","0877408774.B08",
package="flowCore"))
lg1<-logarithm(parameters="FSC-H",a=2,b=1,transformationId="lg1")
transOut<-eval(lg1)(exprs(dat))
``` |