Help:=proc(): print(` Po(k,a), cdfBD(n,p,x), Po2(k,a) `): end: #Po(k,a): The Poisson distribution as the limit of B(n,a/n): Po:=proc(k,a) local n: limit(binomial(n,k)*(a/n)^k*(1-a/n)^(n-k),n=infinity):end: #The CDF for the Binomial distribution from 0 to n*p+x*sqrt(n*p*(1-p)) cdfBD:=proc(n,p,x) local k: add(binomial(n,k)*p^k*(1-p)^(n-k),k=0..trunc(n*p+x*sqrt(n*p*(1-p)))): end: #code by Johnny Fonseca Po2:=proc(k,a) local n: if evalb((whattype(k) = symbol) and (whattype(a) = symbol)) then Physics[Assume](k >= 0, a, 'real'): fi: limit(n!/(k!*(n-k)!)*(a^k)/(n^k)*(1-a/n)^(n-k),n=infinity): end: