I need to compute the rising factorial of big numbers, the best I found until now is the rising factorial function from the sympy package sympy package, that is really nice, but I would still need something faster. What I would need exactly is a really fast version of this: from itertools import combinations from numpy import prod def my_rising_factorial(degree, elt): return sum([prod(i) for i in combinations(xrange(1,degree),elt)]) EDIT: that is given a rising factorial, x(n) = x (x + 1)(x + 2)...(x + n-1), I would like to retrieve a given multiplier of its expanded formula. eg: given: x(6) = x(x + 1)(x + 2)(x + 3)(x + 5)(x + 6) and the expanded form: x(6) = x**6 + 15*x**5 + 85*x**4 + 225*x**3 + 274*x**2 + 120*x I want some how to get one of those multipliers (in this case 1, 15, 85, 225, 274, 120) with "my_rising_factorial()" it works well... but really slowly >>>[my_rising_factorial(6,i) for i in xrange (6)] [1.0, 15, 85, 225, 274, 120] Continue reading...
