Subject: "fastfib" in the gf package faster than "fib"
From: Raymond Toy (RT/EUS)
Date: Tue, 08 Jul 2008 17:46:26 -0400
Michel Talon wrote:
> Stavros Macrakis wrote:
>
>>
>> Still, I'd get a lot more excited by improvements in the speed of
>> polynomial GCD (ubiquitous in calculations in rational (CRE) format)
>> and polynomial factorization --
>> factor(expand((x^230+x+1)*(x^231-x+3))) takes 8 seconds....
>>
>
> By the way this is an example where maxima-gcl and maxima-cmucl have vastly
> different performance:
> niobe% maxima-gcl
> ..
> Maxima 5.14.0 http://maxima.sourceforge.net
> Using Lisp GNU Common Lisp (GCL) GCL 2.6.7 (aka GCL)
> ...
> (%i1) factor(expand((x^230+x+1)*(x^231-x+3)));
> Evaluation took 9.77 seconds...
>
>
> niobe% maxima
> Maxima 5.15.0 http://maxima.sourceforge.net
> Using Lisp CMU Common Lisp Snapshot 2008-04 (19E)
> ...
> (%i1) factor(expand((x^230+x+1)*(x^231-x+3)));
> Evaluation took 26.6700 seconds....
>
>
Perhaps the differences can be accounted for by the fact that two
different versions of maxima are being run? On my machine, gcl (2.6.8)
says:
Evaluation took 46.7300 seconds (75.8100 elapsed)
Cmucl (Snapshot 2008-07) says
Evaluation took 57.7300 seconds (69.2500 elapsed) using 35.077 MB.
Perhaps the difference is also in the platform. (I ran this on a sparc).
BTW, is factor supposed to produce (x^230+x+1)*(x^231-x+3)? It doesn't
for me. I get (x^2+x+1)*(x^228 <more stuff)*(x^231-x+3). Perhaps
that's ok since it seems x^230+x+1 has x^2+x+1 as a factor.
Ray