Cool.
On Tue, Dec 11, 2012 at 7:54 PM, km <[email protected]> wrote: > Apologies: > > a =: 0 { ] > b =: 1 { ] > c =: 2 { ] > roots =: ( (-@b) (+ , -) [: %: *:@b - 4 * a * c ) % 2 * a > roots 1 3 2 > _1 _2 > roots 1 0 1 > 0j1 0j_1 > roots 1 2 1 > _1 _1 > > Kip Murray > > Sent from my iPad > > > On Dec 11, 2012, at 5:29 PM, Roger Hui <[email protected]> wrote: > > > There are some cheeky (or is it cheesy?) versions: > > > > (2*a) %~ (-b) (+,-) %: (b^2) - 4*a*c NB. Kip Murray > > (2*a) %~ - b (+,-) %: (b^2) - 4*a*c > > (+:a) %~ - b (+,-) %: (*:b) - 4*a*c > > -: a %~ - b (+,-) %: (*:b) - 4*a*c > > > > > > > > On Tue, Dec 11, 2012 at 11:37 AM, km <[email protected]> wrote: > > > >> It appears this could be translated into J as the rather cool > >> > >> (2*a) %~ (-b) (+,-) %: (b^2) - 4*a*c > >> > >> Sent from my iPad > >> > >> > >> On Dec 11, 2012, at 12:59 PM, Roger Hui <[email protected]> > wrote: > >> > >>> Example from the Iverson and McDonnell *Phrasal > >>> Forms*<http://www.jsoftware.com/papers/fork.htm>paper (which > >>> introduced fork): > >>> > >>> (-b)(+,-)√((b*2)-4×a×c)÷2×a > >>> > >>> √ is a postulated APL primitive, spelled %: in J. > >>> > >>> > >>> > >>> > >>> On Tue, Dec 11, 2012 at 10:49 AM, km <[email protected]> wrote: > >>> > >>>> What is the coolest way of programming the quadratic formula in J? We > >> are > >>>> finding the roots of polynomial c + x*(b + x*a) without using p. . I > >> offer > >>>> > >>>> roots > >>>> 3 : 0 > >>>> 'a b c' =. y > >>>> q =. %: (b^2) - 4*a*c > >>>> (2*a) %~ (-b) + q,-q > >>>> ) > >>>> roots 1 3 2 > >>>> _1 _2 > >>>> roots 1 0 1 > >>>> 0j1 0j_1 > >>>> roots 1 _2 1 > >>>> 1 1 > >>>> > >>>> partly as problem definition. I am looking for cool roots verbs! > >>>> > >>>> Kip Murray > >>>> > >>>> Sent from my iPad > >>>> > >>>> ---------------------------------------------------------------------- > >>>> For information about J forums see > http://www.jsoftware.com/forums.htm > >>> ---------------------------------------------------------------------- > >>> For information about J forums see http://www.jsoftware.com/forums.htm > >> ---------------------------------------------------------------------- > >> For information about J forums see http://www.jsoftware.com/forums.htm > > ---------------------------------------------------------------------- > > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
