[Jprogramming] A Dot-Graph Rotator

['PMA' via Programming]

Just right.  I've got it as

rotate =: 4 : 0
   <. 0.5 + x (* ^@:j.@:o.&(%&180)) y
)

Yaaay.  Thanks, Henry!

P


On 12/7/23 12:20, Henry Rich wrote:
>    22j10 (* ^@:j.@:o.&(%&180)) 15
> 18.6622j15.3533
>
> Make the middle part a named verb if you like.
>
> Henry Rich
>
> On 12/7/2023 11:48 AM, 'PMA' via Programming wrote:
>> A slightly different approach.  Rather than search out all alignments 
>> and then deduce their degrees of rotation, I mean now to specify as 
>> input the degrees for which rotations are to be generated.
>>
>> Example: given a graph of one dot -- 22j10 -- I'd input that value 
>> with a rotation choice -- 15 degrees counterclockwise -- and expect a 
>> single integer-rounded output value of approximately 19j15.
>> (Those two "15"s are coincidental.)
>>
>> My question is, what J syntax will generate that output?
>>
>> Thanks again for your consideration!
>> Peter A
>>
>>
>> On 11/16/23 09:26, Henry Rich wrote:
>>> This is my reply to a question someone posed yesterday.  This 
>>> afternoon I will post a complete solution.  It's like the puzzle 
>>> problems I posed you, but just a little longer and comes from a real 
>>> user need.  If you want to solve it yourself you will need the 
>>> primitives
>>>
>>> j. dyad, / monad, / dyad, ~, -. dyad, ^ monad, | dyad, -, /: dyad, 
>>> *. monad
>>>
>>> hhr
>>>
>>> On 11/15/2023 6:49 PM, Henry Rich wrote:
>>>> I would find the angles from each point to each other point, take 
>>>> modulus(pi/2), concatenate the list with its negative, and sort. 
>>>> Rotation by each angle produces a new alignment.  Only J primitives 
>>>> are needed.
>>>>
>>>> Use complex numbers to represent the (x,y) values, and *. to 
>>>> convert to angles.
>>>>
>>>> Henry Rich
>>>>
>>>> On 11/15/2023 5:52 PM, 'PMA' via Wiki wrote:
>>>>>
>>>>> Dear J-Wiki,
>>>>>
>>>>> I want to make a script that, given the X/Y values of a 2D 
>>>>> dot-graph, will rotate the graph around its designated origin, 
>>>>> looking for instances of 2 or more points coming into new 
>>>>> horizontal &/or vertical alignment, and at each such instance 
>>>>> output the full set of current X/Y values (integer-rounded).
>>>>>
>>>>> Could you point me to the main needed ingredients?
>>>>>
>>>>> Thanks in advance,
>>>>>
>>>>> Peter Armstrong
>>>>>
>>>>
>>>
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