Check derivations of real77 and real77r

[Daniel Pritchard]

We need to check the derivations / behaviour of real77 and real77r.

Some files that might help are attached.

real_alts.txt
realr_alts.txt

[Daniel Pritchard]

I think the best solutions might be:

frair_real77_alt3 <- function(X, b, q, h, T) {
    a <- (b*X^q)
    return((a*X*T)/(1+a*X*h))
}

frair_real77r_alt3 <- function(X, b, q, h, T) {
    a <- (b*X^q)
    return(X-lamW::lambertW0(a*h*X*exp(-a*(T-h*X)))/(a*h))
}

[Daniel Pritchard]

The real77 family is now deprecated and "replaced" by the flexp* family of models. See commits 2148081 and bcda4fc for the gory details.

[Daniel Pritchard]

The solutions mentioned above have now been implemented as flexp and flexpnr, respectively.