#^:_1 is discussed at
http://www.jsoftware.com/jwiki/Vocabulary/Inverses#Expand_.23.5E:_1
and other inverses are discussed on the same page.
Henry Rich
On 9/11/2014 7:04 AM, Sebastian wrote:
Hi Raul and Dan,
Many thanks for your great help! :)
I found # as copy in the j vocabulary now, but I cannot find #inv. Where
I have to search?
Sebastian
------ Originalnachricht ------
Von: "Raul Miller" <[email protected]>
An: "Programming forum" <[email protected]>
Gesendet: 11.09.2014 12:58:37
Betreff: Re: [Jprogramming] Extend/reduce matrix dimensions
Here's an example of how I frequently use non-truth-valued #
9!:7]9 1 1#'+|-'
Thanks,
--
Raul
On Thu, Sep 11, 2014 at 6:49 AM, Dan Bron <[email protected]> wrote:
Note also that you can use plain, uninverted # to expand arguments:
1 1j1 1 (#!.1) 3 3 $ 0
0 0 0
0 0 0
1 1 1
0 0 0
1 1j1 1 (#!.1"1) 3 3 $ 0
0 0 1 0
0 0 1 0
0 0 1 0
Which approach you pick often depends on whether it's easier for you to
express your expansion vector with length N (complex numbers) or N+1
(boolean numbers).
-Dan
This is worth remembering as well, though I rarely see it used:
1 2 1 # i. 3 3
0 1 2
3 4 5
3 4 5
6 7 8
Please excuse typos; sent from a phone.
> On Sep 11, 2014, at 5:32 AM, Raul Miller <[email protected]>
wrote:
>
> Here are some perhaps relevant examples:
>
> 1 1 0 1 #inv (3 3$ 0)
> 0 0 0
> 0 0 0
> 0 0 0
> 0 0 0
> 1 1 0 1 #inv!.1 (3 3$ 0)
> 0 0 0
> 0 0 0
> 1 1 1
> 0 0 0
> 1 1 0 1 #inv!.1"1 (3 3$ 0)
> 0 0 1 0
> 0 0 1 0
> 0 0 1 0
> 1 1 0 1 #inv!.1"1 (1 1 0 1) #inv!.1 (3 3$ 0)
> 0 0 1 0
> 0 0 1 0
> 1 1 1 1
> 0 0 1 0
> 1 1 0 1 # 1 1 0 1 #inv!.1"1 (1 1 0 1) #inv!.1 (3 3$ 0)
> 0 0 1 0
> 0 0 1 0
> 0 0 1 0
> 1 1 0 1 #("1) 1 1 0 1 # 1 1 0 1 #inv!.1"1 (1 1 0 1) #inv!.1 (3 3$ 0)
> 0 0 0
> 0 0 0
> 0 0 0
> (i.3) 2} 1 1 0 1 #inv (3 3$0)
> 0 0 0
> 0 0 0
> 0 1 2
> 0 0 0
> (i.4) 2}"0 1 (1 1 0 1) #inv"1 (i.3) 2} 1 1 0 1 #inv (3 3$0)
> 0 0 0 0
> 0 0 1 0
> 0 1 2 2
> 0 0 3 0
> (i.4) 2}"0 1 (1 1 0 1) #inv"1 (0 1 3) 2} 1 1 0 1 #inv (3 3$0)
> 0 0 0 0
> 0 0 1 0
> 0 1 2 3
> 0 0 3 0
>
> The whole #inv thing is a bit quirky but was quite deliberate.
This was a
> primitive in APL, but the syntax was ... strange. Rather than
trying to
> find a special symbol for this operation, Iverson put it on #inv
(since -
> logically speaking - it's the inverse of #).
>
> Thanks,
>
> --
> Raul
>
>
>> On Thu, Sep 11, 2014 at 5:21 AM, Sebastian <[email protected]>
wrote:
>>
>> Hi,
>>
>> I know the verbs , ,. ,: to add rows, columns and dimensions to
matrices.
>> It is easy to add these to begin or the end of the corrosponding
dimension,
>> but what is to do, if I want to add one row/column in the middle
of a
>> matrix? Is the only way to slice the matrix in two pieces and
join them
>> with the new row/column?
>>
>> A few examples:
>>
>> Initial situation:
>>
>> 3 3 $ 0
>> 0 0 0
>>
>> 0 0 0
>>
>> 0 0 0
>>
>>
>> add column somewhere to the middle:
>>
>> 0 0 1 0
>>
>> 0 0 1 0
>>
>> 0 0 1 0
>>
>>
>>
>> add row somewhere to the middle:
>>
>> 0 0 1 0
>>
>> 0 0 1 0
>>
>> 1 1 1 1
>>
>> 0 0 1 0
>>
>>
>> remove the added column:
>>
>> 0 0 0
>>
>> 0 0 0
>>
>> 1 1 1
>>
>> 0 0 0
>>
>>
>>
>> and the row:
>>
>>
>>
>> 0 0 0
>>
>> 0 0 0
>>
>> 0 0 0
>>
>>
>>
>> Can anyone help me with this?
>>
>>
>>
>> Regards
>>
>> Sebastian
>>
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>
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