Extracting equation from R code

Dear R-helpers,

I am trying to extract two equations from an R code, but I am not being able
to do it. The code is this:

function (x, fullin, fullout, crossover, infz = 0.953, outfz = 0.047,
     details = FALSE)
{
     if (fullin<  fullout || crossover<  fullout || fullin<  crossover)
         stop("It should be that: fullin>  crossover>  fullout.")
     var.dev<- x - crossover
     inLogOdd<- log(infz/(1 - infz))
     outLogOdd<- log(outfz/(1 - outfz))
     inScalar<- inLogOdd/(fullin - crossover)
     outScalar<- outLogOdd/(fullout - crossover)
     scalars<- rep(NA, length(x))
     scalars[var.dev>  0]<- inScalar
     scalars[var.dev<  0]<- outScalar
     product<- scalars * var.dev
     fz<- exp(product)/(1 + exp(product))
     if (details) {
         ans<- data.frame(x = x, deviations = var.dev, scalars = scalars,
             logOdd = product, membership = fz)
     }
     else ans<- fz
     ans
}

I would like to write the equations for fz as a function of x, fullin,
fullout, and crossover.  I believe the code and the math aren?t that
difficult for many of you. Though as you can see, they are for me. The
equations I could arrive at are the following, but I know they are wrong as
their results aren?t the same as the ones derived from the code:

fz = exp(log(0.953/(1 ? 0.953))/(fullin - crossover)* (x -
crossover))/(1+exp(log(0.953/(1 ? 0.953))/(fullin - crossover)* (x -
crossover)))
for  x>  crossover

and

fz = exp(log(0.047/(1 ? 0.047))/(fullout - crossover)* (x -
crossover))/(1+exp(log(0.047/(1 ? 0.047))/( fullout  - crossover)* (x -
crossover)))
for x<  crossover

Does anyone have any ideas about the right equations?

Thank you,

Tiago

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