[Jprogramming] Verb definition + inadvertent train formation.

[Roger Hui]

Use the phrases =y and =/~y with care.  For example, try it when y has
duplicate elements:

   y=: 3 1 4 1 5 9
   =y
1 0 0 0 0 0
0 1 0 1 0 0
0 0 1 0 0 0
0 0 0 0 1 0
0 0 0 0 0 1
   =/~y
1 0 0 0 0 0
0 1 0 1 0 0
0 0 1 0 0 0
0 1 0 1 0 0
0 0 0 0 1 0
0 0 0 0 0 1




On Mon, Nov 19, 2012 at 9:22 PM, Don & Cathy Kelly <dhky at shaw.ca> wrote:

> That should be in the phrases rather than what I used!
> Ric's definition also  works but not with a 5 element list
>    y=:2 3 6 8 9
>    = y
> 1 0 0 0 0
> 0 1 0 0 0
> 0 0 1 0 0
> 0 0 0 1 0
> 0 0 0 0 1
>    =/~y
> 1 0 0 0 0
> 0 1 0 0 0
> 0 0 1 0 0
> 0 0 0 1 0
> 0 0 0 0 1
>
> Thank you both - so many ways to skin a cat!
>
> Don
> On 19/11/2012 9:01 PM, Bo Jacoby wrote:
>
>> The unit matrix is
>>     =/~i.5
>> 1 0 0 0 0
>> 0 1 0 0 0
>> 0 0 1 0 0
>> 0 0 0 1 0
>> 0 0 0 0 1
>>
>> - Bo
>>
>>
>>
>>
>>
>>  ______________________________**__
>>> Fra: Don & Cathy Kelly <dhky at shaw.ca>
>>> Til: programming at jsoftware.com
>>> Sendt: 0:47 tirsdag den 20. november 2012
>>> Emne: Re: [Jprogramming] Verb definition + inadvertent train formation.
>>>
>>> No - I should have made it clear that the actual y is a list of n
>>> numbers and I need to add this list to the diagonal of a matrix.
>>> Since this will (of necessity) be within a loop and each time both the
>>> list and matrix will be modified (except for size),
>>> I have come to the conclusion that I should make a single unit matrix
>>> outside the iteration and use this each time.
>>>     ] u=:=@i.@#i.5
>>>
>>> 1 0 0 0 0
>>> 0 1 0 0 0
>>> 0 0 1 0 0
>>> 0 0 0 1 0
>>> 0 0 0 0 1
>>>
>>> y=: 2 3 5 4 10
>>>
>>>      ]u *y
>>> 2 0 0 0  0
>>> 0 3 0 0  0
>>> 0 0 5 0  0
>>> 0 0 0 4  0
>>> 0 0 0 0 10
>>> repeating with different y values as needed.
>>>
>>> The algorithm for u is taken from the "phrases" section of the
>>> vocabulary-maybe you have a simpler one?-
>>> Thanks
>>>
>>> Don
>>>
>>>
>>> On 18/11/2012 10:33 PM, bob therriault wrote:
>>>
>>>> Hi Don,
>>>>
>>>> Are you looking for
>>>>
>>>> y=:5
>>>>       c=:(*=)&i.
>>>>       c y
>>>> 0 0 0 0 0
>>>> 0 1 0 0 0
>>>> 0 0 2 0 0
>>>> 0 0 0 3 0
>>>> 0 0 0 0 4
>>>> Cheers, bob
>>>>
>>>> On 2012-11-18, at 7:13 PM, Don & Cathy Kelly wrote:
>>>>
>>>>  OOPs' I meant y=:i.5 5
>>>>>
>>>>> Don
>>>>> On 18/11/2012 7:04 PM, Don & Cathy Kelly wrote:
>>>>>
>>>>>> That gives the diagonal nicely  but the problem that I didn't express
>>>>>> clearly is that I want a matrix as follows
>>>>>>      y=:i.5
>>>>>>
>>>>>>      ]result =: (* =@i.@#) y
>>>>>> 0 0 0 0 0
>>>>>> 0 1 0 0 0
>>>>>> 0 0 2 0 0
>>>>>> 0 0 0 3 0
>>>>>> 0 0 0 0 4
>>>>>> which II can get by
>>>>>> c=:* =@i.@#
>>>>>>      c y
>>>>>> 0 0 0 0 0
>>>>>> 0 1 0 0 0
>>>>>> 0 0 2 0 0
>>>>>> 0 0 0 3 0
>>>>>> 0 0 0 0 4
>>>>>>
>>>>>> For my purposes I can use a base nth order unit matrix by the phrase
>>>>>> as given in phrases as  m=:=@i.@# y
>>>>>> and then deal with m* y1 , m* y2 etc which suits my purpose which is
>>>>>> to form a specific Jacobean used for power system load flows.
>>>>>> I have handled this problem in APL  and am trying to replicate the
>>>>>> coding more directly in J-mainly as an exploration of J for my own
>>>>>> satisfaction.
>>>>>>
>>>>>> Thank you
>>>>>>
>>>>>> Don Kelly
>>>>>>
>>>>> ------------------------------**------------------------------**
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>>>> forums.htm <http://www.jsoftware.com/forums.htm>
>>>>
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>>>
>>>
>>>
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>>
>>
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>