I'm not clear about what you want.
You start with 4x4
You then double the rows to get 8x4
You then do something else, leaving 8x4 (?)
You then multiply by 4x2, leaving 8x2 (?)
Now you want to get back to 4x4? Do you just want to run each pair of
rows together to make one row of the result?
If so,
_2 ,\ i. 8 2
Henry Rich
On 9/5/2012 6:36 PM, pascha wrote:
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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