Most awsome! thanks.
----- Original Message Follows ----- From: Roger Hui <[email protected]> To: Programming forum <[email protected]> Subject: Re: [Jprogramming] perfect power??? Date: Mon, 08 Jun 2009 16:11:41 -0700 >Somewhere in the bowels of q: it calls 1&p: >before launching into the much more expensive >factoring routine. > >It seems to me there should be a straightforward >determination of whether a number y is a perfect power: >just try all possible exponents from 2 to 2 >....@^. y . >For example, for 2^607x the exponents are from 2 to 607, >which is not many exponents to try. Thus: > >pp=: 3 : 0 > for_e. 2+i.>.2^.y do. > m=. e <....@%: y > if. y=m^x: e do. m,e return. end. > end. > '' >) > > pp 81 >9 2 > pp 128 >2 7 > pp 125 >5 3 > pp 2^100x >1125899906842624 2 > pp <:2^607x > > 6!:2 'pp <: 2^607x' >0.159832 > >pptest=: *...@#@pp > > > > >----- Original Message ----- >From: Raul Miller <[email protected]> >Date: Monday, June 8, 2009 15:32 >Subject: Re: [Jprogramming] perfect power??? >To: Programming forum <[email protected]> > >> On Mon, Jun 8, 2009 at 6:13 PM, >> <[email protected]> wrote: >> > From what I am read in this article, determing if a >> > number is a "Perfect Power" should be >> > a lot faster. Either that or I am totally mis-reading >> > the article. >> >> Determining if a number is a perfect power is certainly >> faster than some algorithm for determining if a number >> is prime. >> >> But do you have any reason to believe J uses that >> algorithm, in its implementation of q? >> >> That said, 1 p: will determine whether or not a number >> is prime, and might be faster than 1 = # q: in some >> cases. >----------------------------------------------------------- >----------- For information about J forums see >http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
