Henry Rich wrote:
>
>
>
> On 9/5/2012 6:18 PM, pascha wrote:
>>
>> sorry for quick posts by me.. I am newbie in J
>> I want to solve a linear system of equation and I want to get a desirable
>> design matrix for the equation
>> considering a simple case of 4 x 4 matrix i. 4 4:
>> 0 1 2 3
>> 4 5 6 7
>> 8 9 10 11
>> 12 13 14 15
>>
>> could you give a strategy to duplicate each row and get a 8 x 4 matrix,
>> e.g.
>> :
>> 0 1 2 3
>> 0 1 2 3
>> 4 5 6 7
>> 4 5 6 7
>> 8 9 10 11
>> 8 9 10 11
>> 12 13 14 15
>> 12 13 14 15
>>
>
> Just do
>
> 2 # mtx
>
>
>> At the end for each duplicate array I want to multiply them by another 2
>> x 4
>> matrix (say, 1 1 0 0,. 0 1 1 1) and get the final design matrix. Is the
>> solution come with the concept of boxing in this situation?
>>
>
> Boxing may not be needed. Matrix multiply is
>
> +/ . *
>
> and you can just
>
> mp =: +/ . *
>
> mtx mp (1 1 0 0,. 0 1 1 1)
>
>
> Henry Rich
>
> Thanks
> well, I want to do array by array multiplication:
> so If I have i. 4 4 the result should be again a 4 x 4 or 4 x 8 matrix,
> like this:
> 0 1 0 0
> 0 5 6 7
> 8 9 0 0
> 0 13 14 15
>
> that's why I though about boxing
>
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