Re: Fun with Unbounded Rational Numbers

[Paul Rubin <no.email@nospam.invalid>]

"Jeffrey R. Carter" <spam.jrcarter.not@spam.not.acm.org> writes:
> The implementation is
>
>       X := R / Two;
>       All_Iterations : for I in 1 .. 15 loop
>          Y := X ** 2 - R;
>          exit All_Iterations when abs Y < A;   ...


Can you instrument this loop to check how many iterations are actually
being executed, and preferably how long each one takes?

The same calculation in compiled Haskell takes about 0.012 cpu seconds
including printing the answer, which is about 50k chars (i.e. 25k digits
for each of the numerator and denominator).

Doing 25 iterations takes about 2 minutes and uses around 250MB of
memory, giving an answer of around 50M chars.

You should get within 1e-8 or whatever it was in less than 5 iterations.