Compounding (version 1.0.2)

pgfIpoisson: Function pgfIpoisson

Description

This function calculates value of the pgf's inverse of the Poisson distribution.

Usage

pgfIpoisson(s, params)

Arguments

s

Value of the parameter of the pgf. It should be from interval [-1,1]. In the opposite pgf diverges.

params

Positive parameter of the Poisson distribution, such that params<-theta.

References

Johnson N, Kotz S, Kemp A (1992) Univariate Discrete Distributions, John Wiley and Sons, New York

http://www.am.qub.ac.uk/users/g.gribakin/sor/Chap3.pdf

Examples

params<-7
pgfIpoisson(.5,params)


## The function is currently defined as

pgfIpoisson <- function(s,params) {
k<-s[abs(s)>1]
if (length(k)>0)
    warning("At least one element of the vector s are out of interval [-1,1]")
 if (length(params)>1) stop("The length of params is 1")
    theta<-params[1]
if (theta<=0) 
    stop ("Parameter of Poisson distribution must be positive")
    1+log(s)/theta
}