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 Index]