R: Generalized logit and inverse logit function

logit {gtools} | R Documentation

## Generalized logit and inverse logit function

### Description

Compute generalized logit and generalized inverse logit functions.

### Usage

    logit(x, min = 0, max = 1)

    inv.logit(x, min = 0, max = 1)

### Arguments

`x` | value(s) to be transformed
`min` | Lower end of logit interval
`max` | Upper end of logit interval

### Details

The generalized logit function takes values on [min, max] and transforms them to span [-Inf,Inf] it is defined as:

y = log(p/(1-p))

where

p=(x-min)/(max-min)

The generalized inverse logit function provides the inverse transformation:

x = p * (max-min) + min

where

exp(y)/(1+exp(y))

### Value

Transformed value(s).

### Author(s)

Gregory R. Warnes greg@warnes.net

### See Also

`logit`

### Examples

    x <- seq(0, 10, by = 0.25)
    xt <- logit(x, min = 0, max = 10)
    cbind(x, xt)

    y <- inv.logit(xt, min = 0, max = 10)
    cbind(x, xt, y)

[Package gtools version 3.9.2.2 Index]