I came to say something similar, though I would use: while (1) { ... if (!n) { ... return 1 - ab * rsqrt_a2 * rsqrt_b2; } } Also, th

I came to say something similar, though I would use: while (1) { ... if (!n) { ... return 1 - ab * rsqrt_a2 * rsqrt_b2; } } Also, the "So let’s use the common Pythonic zip idiom:" version is missing the sqrt calls so doesn't give the same answer as the first version.