[R] A matrix automation problem
Ben Bolker
bolker at ufl.edu
Wed Oct 22 15:43:04 CEST 2008
megh <megh700004 <at> yahoo.com> writes:
>
>
> [I am really sorry if it is double posted, I doubt me previous post could not
> reach forum due to some problem with net]
>
> Suppose I have a matrix :
>
> a = matrix(1:9, 3)
>
> >From this matrix, I construct 9 additional matrices :
>
> i = 1:9
> bi = a * i
>
> Now combining all those 9 new matrices, I construct a final metrix as :
>
> c =
>
> b1 b4 b7
> b2 b5 b8
> b3 b6 b8
>
> I want to automate this procedure for any arbitrary number "i"
>
It may be too specialized, but it sounds like you're looking
for a Kronecker product.
a = matrix(1:9,3)
> kronecker(a,a)
[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9]
[1,] 1 4 7 4 16 28 7 28 49
[2,] 2 5 8 8 20 32 14 35 56
[3,] 3 6 9 12 24 36 21 42 63
[4,] 2 8 14 5 20 35 8 32 56
[5,] 4 10 16 10 25 40 16 40 64
[6,] 6 12 18 15 30 45 24 48 72
[7,] 3 12 21 6 24 42 9 36 63
[8,] 6 15 24 12 30 48 18 45 72
[9,] 9 18 27 18 36 54 27 54 81
Ben Bolker
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