title: Binomial test in Python for very large numbers
body: <p>I need to do a binomial test in Python that allows calculation for 'n' numbers of the order of 10000.</p>
  
  <p>I have implemented a quick binomial_test function using scipy.misc.comb, however, it is pretty much limited around n = 1000, I guess because it reaches the biggest representable number while computing factorials or the combinatorial itself. Here is my function:</p>
  
  <pre><code>from scipy.misc import comb
  def binomial_test(n, k):
      """Calculate binomial probability
      """
      p = comb(n, k) * 0.5**k * 0.5**(n-k)
      return p
  </code></pre>
  
  <p>How could I use a native python (or numpy, scipy...) function in order to calculate that binomial probability? If possible, I need scipy 0.7.2 compatible code.</p>
  
  <p>Many thanks!</p>