[seqfan] Re: insufficient gp/pari precision gives incorrect results

Joerg Arndt arndt at jjj.de
Tue Oct 13 11:46:46 CEST 2009


Pari computes the continued fraction to as many terms as possible with
the precision used.  This is the only reasonable behavior.

If you had attempted to actually make any meaningful statement, you'd
would have found this out yourself.  But why waste those precious 15
seconds when 300 people can spent several enjoyable minutes guessing
what you could have possibly meant?

btw:

? 534!
227355912849950585372224398471789103380497111873365714174962870186250889921221377133674779151847932996179955323060840188256913669797148941567329899289622839954980433752676061170245867811209920852136742773635142408672154292462689377058279709216725729094846196525918258243319333389342551574174942527330164754015475586876036734008035109079047866929853598226891907890984541285287299406444229461026997431051601794630312541426390915710871650922429548283406691171700917703040647066006728084506774908471316539794207797636640599929389081956056412301219463754169807733566812461403407764391553509214535152320703919331070332755144107129567547542625604340574579758395079797847591942913810516698958392006157975110353148480402986423546330255892860187558959920485061059501350721177659332901538362090435613412945646535690166827668527215232560488615105435000691175080121434193739179326477536664498170209003486284466767977967321613092675977854453408750956964332246129461213162697013283494033090323194836336720353419600656814496111099257927243781927402208022664958683552844580246386763067480262099665861707236691148800000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000

That's not what I want, this needs to be fixed.


* Georgi Guninski <guninski at guninski.com> [Oct 13. 2009 20:23]:
> insufficient gp/pari precision gives incorrect results.
> probably this feature should be documented.
> i got hit by it in mass pari computations.
> 
> example session:
> A078976 Numerator of n-th convergent to e^(2/3)
> 
> parisize = 8000000, primelimit = 500000
> ? a(n)=component(component(contfracpnqn(contfrac(exp(2/3), n)), 1), 1)
> ? n=150
> %1 = 150
> ? a1=a(n)
> %2 = 8775965436819116582
> ? default(realprecision,300)
> %3 = 300
> ? a1=a(n)
> %4 =
> 1662089248224191266325975305441010031166997357354140605757488607965909355236108828684398094504604203059026215637276539867276263951376657621927749105770538
> ? default(realprecision,3000)
> %5 = 3000
> ? a1=a(n)
> %6 =
> 666280308971067538803113985595492989367403873213980495571359635598141444179643386508726043481092812835676179552224737408022484748450993933584137176738055064772678238280831940888731615490091677245778769175071
> ? default(realprecision,30000)
> %7 = 30000
> ? a1=a(n)
> %8 =
> 666280308971067538803113985595492989367403873213980495571359635598141444179643386508726043481092812835676179552224737408022484748450993933584137176738055064772678238280831940888731615490091677245778769175071
> 
> 
> _______________________________________________
> 
> Seqfan Mailing list - http://list.seqfan.eu/




More information about the SeqFan mailing list