On Fri, Feb 14, 2025 at 07:30:59AM -0800, Lindsay Lawrence wrote:
> On Thu, Feb 13, 2025 at 9:49 PM Lindsay Lawrence <
> [email protected]> wrote:
>
>
> > A bit of searching came up with the paper with the haskell version
> >
> > https://www.cs.ox.ac.uk/people/jeremy.gibbons/publications/spigot.pdf
> >
> > Interestingly enough there is another version of PI in there, recursive,
> > based on the Gosper series,
> > that a faster... although it is based on a conjecture they haven't proven
> > in that paper.
> >
> > The picolisp version of that one is below ('tco' is a nice fit for it as
> > well!)
> >
>
> There was an error in the variable scoping of the function I posted in
> previous email. Here is the corrected version
>
> (de makePi (N)
> (let (G 1 R 180 S 60 I 2)
> (tco (G R S I N)
> (let
> (U (* 3 (+ (* 3 I) 1) (+ (* 3 I) 2) )
> Y (/ (+ (* G (- (* 27 I) 12)) (* 5 R) ) (* 5 S) ) )
> (prin Y)
> (if (or (not N) (gt0 N))
> (tc
> (* 10 G I (- (* 2 I) 1))
> (* 10 U (- (+ (* G (- (* 5 I) 2)) R) (* Y S) ) )
> (* S U)
> (+ I 1)
> (dec N) ) ) ) ) ))
Wow, that's cool! I'll measure it now :)
How about a coroutine version?
(de pi (Flg)
(if Flg
(co 'pi
(yield 3)
(yield ".")
(let (G 60 R 13440 S 10080 I 3)
(tco (G R S I)
(let
(U (* 3 (inc (* 3 I)) (+ (* 3 I) 2))
Y (/ (+ (* G (- (* 27 I) 12)) (* 5 R) ) (* 5 S)) )
(yield Y)
(tc
(* 10 G I (dec (* 2 I)))
(* 10 U (- (+ (* G (- (* 5 I) 2)) R) (* Y S )))
(* S U)
(inc I) ) ) ) ) )
(co 'pi) ) )
(de prinPi (N)
(do N
(prin (pi T)) )
(pi)
(prinl) )
☺/ A!ex
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