Calculate pi up to n digits

make_pi.py

import sys

def make_pi(digits):
    def _make_pi(digits):
        q, r, t, k, m, x = 1, 0, 1, 1, 3, 3
        count = -1
        for j in range(sys.maxsize):
            if count >= digits:
                break
            if 4 * q + r - t < m * t:
                count += 1
                yield m
                q, r, t, k, m, x = 10*q, 10*(r-m*t), t, k, (10*(3*q+r))//t - 10*m, x
            else:
                q, r, t, k, m, x = q*k, (2*q+r)*x, t*x, k+1, (q*(7*k+2)+r*x)//(t*x), x+2
    n=[str(i) for i in _make_pi(digits)]
    n = n[:1] + ['.'] + n[1:]
    return ''.join(n)