From: Mark Dickinson Date: Sun, 16 Jun 2019 16:53:21 +0000 (+0100) Subject: Turn math.isqrt assertion into a comment to clarify its purpose. (GH-14131) X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=2dfeaa9222e2ed6b6e32faaf08e5b0f77318f0a7;p=python Turn math.isqrt assertion into a comment to clarify its purpose. (GH-14131) --- diff --git a/Modules/mathmodule.c b/Modules/mathmodule.c index 76d821c65b..82a9a14724 100644 --- a/Modules/mathmodule.c +++ b/Modules/mathmodule.c @@ -1527,10 +1527,10 @@ Here's Python code equivalent to the C implementation below: a = 1 d = 0 for s in reversed(range(c.bit_length())): + # Loop invariant: (a-1)**2 < (n >> 2*(c - d)) < (a+1)**2 e = d d = c >> s a = (a << d - e - 1) + (n >> 2*c - e - d + 1) // a - assert (a-1)**2 < n >> 2*(c - d) < (a+1)**2 return a - (a*a > n)