function L = Laguerre(a, i, x)
%
% Laguerre: L = Laguerre(a, i, x);
%
% Compute the generalized Laguerre polynomial of degree i according to
% Eq. 18 of B-0002. The argument i may be a vector.
%

N = size(i,1);
L = zeros(N,1);

for j = 1: N
  k = 0:i(j);
  pk = cumprod(a+k); % k+1 -th element of this vector = (1+a)_k of B-0002
  L(j) = pk(i(j)+1) * sum((-x).^k ./ (pk .* gamma(k+1) .* gamma(i(j)-k+1)));
end