R/pbs.R

In sads: Maximum Likelihood Models for Species Abundance Distributions

pbs <- function(q, N, S, lower.tail=TRUE, log.p = FALSE){
    N[ !is.finite(N) | N <= 0] <- NaN
    S[ !is.finite(S) | S <= 0] <- NaN
    y <- 1 + N*(1-q/N)^S/(q-N)
    y[q < 0] <- 0; y[q >= N] <- 1
    if(!lower.tail) y <- 1 - y
    if(log.p) y <- log(y)
    if(any(is.nan(y))) warning("NaNs produced")
    return(y)
}