R/raffinity.MH.R

In melmasri/HPprediction: Host-parasite prediction based on phylogeny

raffinity.MH <-
function(old, z, Ud, sig=0.1, hyper){
    a = hyper[1]
    b = hyper[2]
    epsilon = rnorm(length(old), 0, sd = sig)
    new = old +  -2*(old + epsilon <=0)*epsilon + epsilon    

    likeli = (z+a-1)*log(new/old) -  (new - old)*(b +Ud)
    
    ratio = pmin(1, exp(likeli))
    u = 1*(runif(length(old))<=ratio)
    u*new + (1-u)*old
}