Challenge: optimizing isqrt

[Chris Angelico]

On Sat, Nov 1, 2014 at 7:25 PM, Christian Gollwitzer <auriocus at gmx.de> wrote:
>> Part of the point of that algorithm is that it never uses FP, and is
>> therefore not limited by FP restrictions.
>
>
> which are???

Most notably, the inability to represent every integer beyond 2**53,
and the inability to represent any integer beyond 2**1024. This
algorithm should work fine with any positive integer.

ChrisA