2.60 repeat each column of matrix number of times

Gives a matrix, repeate each column a number of time, say 3 times, in place to produce a matrix 3 times as wide as the original.

kron() in Matlab and KroneckerProduct in Mathematica and Maple can be used for this.

Mathematica mat = {{1, 2, 3, 4}, {5 , 6, 7, 8}, {9, 10, 11, 12}} KroneckerProduct[mat, {1, 1, 1}] Another method that can be used in this, but the above is better r = Map[#*{1, 1, 1} &, mat, {2}] Partition[Flatten[r], 12]

{{1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4}, {5, 5, 5, 6, 6, 6, 7, 7, 7, 8, 8, 8}, {9, 9, 9, 10, 10, 10, 11, 11, 11, 12, 12, 12}}

 

Matlab A=[1 2 3 4; 5 6 7 8; 9 10 11 12]; kernel=ones(1,3); kron(A,kernel)

ans = 1 1 1 2 2 2 3 3 3 4 4 4 5 5 5 6 6 6 7 7 7 8 8 8 9 9 9 10 10 10 11 11 11 12 12 12

 

Maple restart; mat := Matrix([[1, 2, 3,4], [5, 6,7,8], [9,10,11,12]]); kernel := Vector[row]([1,1,1]); LinearAlgebra:-KroneckerProduct(mat,kernel);

\[ \left [\begin {array}{cccccccccccc} 1 & 1 & 1 & 2 & 2 & 2 & 3 & 3 & 3 & 4 & 4 & 4 \\ 5 & 5 & 5 & 6 & 6 & 6 & 7 & 7 & 7 & 8 & 8 & 8 \\ 9 & 9 & 9 & 10 & 10 & 10 & 11 & 11 & 11 & 12 & 12 & 12 \end {array}\right ] \]