1pbetap=function(ab,n,s)
2{
3#
4# PBETAP Predictive distribution of number of successes in future binomial
5#	experiment with a beta prior. PRED = PBETAP(AB,N,S) returns a vector
6#	PRED of predictive probabilities, where AB is the vector of beta
7#	parameters, N is the future binomial sample size, and S is the vector of
8#	numbers of successes for which predictive probabilities will be computed.
9#------------------------
10# Written by Jim Albert
11# albert@bgnet.bgsu.edu
12# November 2004
13#------------------------
14
15pred=0*s;
16a=ab[1]; b=ab[2];
17
18lcon=lgamma(n+1)-lgamma(s+1)-lgamma(n-s+1);
19
20pred=exp(lcon+lbeta(s+a,n-s+b)-lbeta(a,b));
21
22return(pred)
23}
24