Thanks, Linda, I like this. Was trying to stay close to the Iverson-McDonnell
formula. Kip
Sent from my iPad
On Dec 12, 2012, at 2:24 AM, "Linda Alvord" <lindaalv...@verizon.net> wrote:
> Kip, Here are two thoughts:
>
>
>
> This uses [: only rather than both [: and @
>
> %~ can be "read" as "into" (it makes a prettier tree!)
>
>
>
> a =:0 { ]
>
> b =:1 { ]
>
> c =:2 { ]
>
> roots2=:(2*a)%~([:-b)(+,-)[:%:([:*:b)-4*a*c
>
> roots2 1 3 2
>
> _1 _2
>
> roots2 1 0 4
>
> 0j2 0j_2
>
> 5!:4 <'roots2'
>
> ┌─ 2
> ┌─────┼─ *
> │ └─ a
> │
> ├─ ~ ─── %
> │ ┌─ [:
> ──┤ ┌───┼─ -
> │ │ └─ b
> │ │
> │ │ ┌─ +
> │ ├───┼─ ,
> └─────┤ └─ -
> │
> │ ┌─ [:
> │ ├─ %:
> │ │ ┌─ [:
> └───┤ ┌───┼─ *:
> │ │ └─ b
> │ ├─ -
> └────┤ ┌─ 4
> │ ├─ *
> └───┤ ┌─ a
> └────┼─ *
> └─ c
>
>
>
> Linda
>
>
>
> -----Original Message-----
> From: programming-boun...@forums.jsoftware.com
> [mailto:programming-boun...@forums.jsoftware.com] On Behalf Of Roger Hui
> Sent: Wednesday, December 12, 2012 2:23 AM
> To: Programming forum
> Subject: Re: [Jprogramming] Cool roots
>
>
>
> Cool.
>
>
>
>
>
>
>
>
>
> On Tue, Dec 11, 2012 at 7:54 PM, km < <mailto:k...@math.uh.edu>
> k...@math.uh.edu> 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 < <mailto:rogerhui.can...@gmail.com>
>> rogerhui.can...@gmail.com> 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 < <mailto:k...@math.uh.edu>
>>> k...@math.uh.edu> 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 <
>>>> <mailto:rogerhui.can...@gmail.com> rogerhui.can...@gmail.com>
>
>> wrote:
>
>>>>
>
>>>>> Example from the Iverson and McDonnell *Phrasal
>
>>>>> Forms*< <http://www.jsoftware.com/papers/fork.htm>
>>>>> 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 < <mailto:k...@math.uh.edu>
>>>>> k...@math.uh.edu> 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> http://www.jsoftware.com/forums.htm
>
>>>>> ------------------------------------------------------------------
>
>>>>> ---- For information about J forums see
>
>>>>> <http://www.jsoftware.com/forums.htm> http://www.jsoftware.com/forums.htm
>
>>>> -------------------------------------------------------------------
>
>>>> --- For information about J forums see
>
>>>> <http://www.jsoftware.com/forums.htm> http://www.jsoftware.com/forums.htm
>
>>> --------------------------------------------------------------------
>
>>> -- For information about J forums see
>
>>> <http://www.jsoftware.com/forums.htm> http://www.jsoftware.com/forums.htm
>
>> ----------------------------------------------------------------------
>
>> For information about J forums see <http://www.jsoftware.com/forums.htm>
>> http://www.jsoftware.com/forums.htm
>
>>
>
> ----------------------------------------------------------------------
>
> For information about J forums see <http://www.jsoftware.com/forums.htm>
> http://www.jsoftware.com/forums.htm
>
> ----------------------------------------------------------------------
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