You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: dirichlet_sample.m
    path of file: ./repos/bnt/KPMstats
    
    the code of the file until where you have to start completion: function theta = dirichlet_sample(alpha, N)
% SAMPLE_DIRICHLET Sample N vectors from Dir(alpha(1), ..., alpha(k))

    
function theta = dirichlet_sample(alpha, N)
% SAMPLE_DIRICHLET Sample N vectors from Dir(alpha(1), ..., alpha(k))
% theta = sample_dirichlet(alpha, N)
% theta(i,j) = i'th sample of theta_j, where theta ~ Dir

% We use the method from p. 482 of "Bayesian Data Analysis", Gelman et al.

assert(alpha > 0);
k = length(alpha);
theta = zeros(N, k);
scale = 1; % arbitrary
for i=1:k
  %theta(:,i) = gamrnd(alpha(i), scale, N, 1);
  theta(:,i) = gamma_sample(alpha(i), scale, N, 1);
end