R/util-transform.R

In fitdistrplus: Help to Fit of a Parametric Distribution to Non-Censored or Censored Data

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#   Copyright (c) 2009 Marie Laure Delignette-Muller, Christophe Dutang                                                                                                  
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### Infinitely differentiable transformations of R into a bounded or half-bounded interval
###
###         R functions
### 


#inverse are useless?


#Transformation from (-Inf, +Inf) to (-1, 0)
Tm10 <- function(x)
  -1/(1+exp(-x))
#Inverse
iTm10 <- function(x) 
  log(-x/(1+x))

#Transformation from (-Inf, +Inf) to (0, 1)
T01 <- function(x)
  1/(1+exp(-x))
#Inverse
iT01 <- function(x)
  log(x/(1-x))

#Transformation from (-Inf, +Inf) to (0, +Inf)
T0Inf <- function(x)
  exp(x)
#Inverse
iT0Inf <- function(x)
  log(x)

#Transformation from (-Inf, +Inf) to (1, +Inf)
T1Inf <- function(x)
  1+exp(x)
#Inverse
iT1Inf <- function(x)
  log(x-1)