$i.5 6
5 6
R.E. Boss wrote:
>
>
> _1 (4 : '(,y)([#~ (x|~]) = |~) >:{:$y') i.5 5
> 5 11 17 23
>
> _1 (4 : '(,y)([#~ (x|~]) = |~) >:{:$y') i.5 6
> 6 13 20 27
>
> 3 2 finddiag~ i.5 6
> |length error: finddiag
> | 3 2 finddiag~i.5 6
>
>
> R.E. Boss
>
>
> -----Oorspronkelijk bericht-----
> Van: [email protected]
> [mailto:[email protected]] Namens Viktor Cerovski
> Verzonden: donderdag 10 november 2011 10:52
> Aan: [email protected]
> Onderwerp: Re: [Jprogramming] selecting from two different matrices based
> on
> a comparison.
>
>
> I find your post quite convoluted. Here's what I read:
>
> Nick Simicich-2 wrote:
>>
>> (I figured out an answer for the first question - I don't ask unless I
>> search thoroughly, and I finally found it, so I am going to leave it in
>> case the answer helps someone else.)
>>
>> I have an array that can be any of a couple different square sizes. I
>> wanted to determine which of the diagonals the coordinates I was
>> processing
>> was, so I made a list of the coordinates that were on the diagonals,[...]
>>
> Problem:
> Given a square matrix, return diagonal that contains element with
> coordinates i j.
>
> Solution:
>
> finddiag =: ,@[ #~ -/@] = ,@:(-/~@i.@#)@[
>
> The solution uses the fact that i-j (i and j are in y) gives the number
> of
> the diagonal,
> and then uses the number to extract the corresponding diagonal from x (the
> matrix.)
>
> ]mat=.i.5 5
> 0 1 2 3 4
> 5 6 7 8 9
> 10 11 12 13 14
> 15 16 17 18 19
> 20 21 22 23 24
>
> mat finddiag 3 2
> 5 11 17 23
>
> (<3 2){mat
> 17
>
> Note that finddiag does not make coordinates of diagonal elements.
>
>
>
>> I have a second question. I wanted to make two x by x matrices, and
>> compare one of those matrices to a scalar, building a single matrix by
>> extracting from each one. What I wanted to do was to code some variation
>> of. I had a matrix where the filled in pieces were ordinary numbers and
>> the placeholders were _. I had a second matrix that had candidates, but
>> they were not
>>
>> (a=b) { mat1,.mat2
>>
>> That does nothing like I want - because it just plain does not work.
>> Every
>> zero and one selects the whole array, and changing the rank of {, as {"1,
>> {"2 etc just does not work.
>>
>> What I ended up doing was
>>
>> ((a=b)*mat1)+(-.a=b)*mat2
>>
>> Now, that worked because I happened to have numeric matrices. If I'd had
>> character arrays, I might have had to map them into numeric arrays to get
>> this sort of thing to work at all.
>>
>> Is the math trick the only way to do this?
>>
> Here I couldn't formulate a problem based on your post.
> --
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> rison.-tp32816282s24193p32817267.html
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>
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