title: python log n choose k
body: <p>scipy.misc.comb, returning n choose k, is implemented using the gammaln function. Is there a function that stays in log space? I see there is no scipy.misc.combln or any similar. It is trivial to implement myself, but it would be convenient if it were already in a package somewhere. I don't see it in scipy.misc, and it just feels wasteful to convert to normal space and then back to log.</p>