void randirmult(double *pp, int *aa, int len, int m)
{
/**
compound dirichlet - Multinomial
*/
double *x ;
if (len==0) return ;
if (len==1) {
aa[0] = m ;
return ;
}
ZALLOC(x, len, double) ;
randirichlet(x, pp, len) ;
ranmultinom(aa, m, x, len) ;
free(x) ;
}
void ranmultinom(int *samp, int n, double *p, int len)
// multinomial sample p is prob dist n samples returned
// work is O(len^2) which is silly
{
int x ;
double *pp ;
if (len==0) return ;
ivzero(samp, len) ;
if (n<=0) return ;
if (len==1) {
samp[0] = n ;
return ;
}
ZALLOC(pp, len, double) ;
copyarr(p, pp, len) ;
bal1(pp, len) ;
samp[0] = x = ranbinom(n, pp[0]) ;
ranmultinom(samp+1, n-x, p+1, len-1) ;
free(pp) ;
}