generate matrix by for loop

A=[1 -10 4

0 -2 7

5 1 9]

I need to get

A=[1 0 -10 0 4

0 0 -2 0 7

5 0 1 0 9]

by for loop

[David Meissner]

I would look into "Indexing with a Single Index" here: https://www.mathworks.com/help/matlab/math/array-indexing.html

Answer 1

[DGM]

Don't need a loop.

A = [1 -10 4
    0  -2  7
    5  1  9];

B = zeros(size(A,1),2*size(A,2)-1); % allocate
B(:,1:2:end) = A % fill in nonzero columns

B = 3×5

1 0 -10 0 4 0 0 -2 0 7 5 0 1 0 9

[Mako]

How to inert matrix in loop?

[Mako]

And if I want to increase size 20X20?

[DGM]

The above code doesn't depend on the size of A. A can be any 2D array.

A loop is not necessary. If you want to use a loop anyway, you can preallocate the output array and assign data columnwise.

A = [1 -10 4
    0  -2  7
    5  1  9];

B = zeros(size(A,1),2*size(A,2)-1); % allocate
cv = 1:2:size(B,2); % column indices of the output array
for c = 1:size(A,2)
    B(:,cv(c)) = A(:,c); % fill in nonzero columns
end
B

B = 3×5

1 0 -10 0 4 0 0 -2 0 7 5 0 1 0 9

[Mako]

Sorry, I may have asked the wrong question above.

If matrix size is:

A=[1 0 -10 0 4 0 1 0 -10 0 4 0

0 0 -2 0 7 0 0 0 -2 0 7 0

5 0 1 0 9 0 5 0 1 0 9 0

1 0 -10 0 4 0 1 0 -10 0 4 0

0 0 -2 0 7 0 0 0 -2 0 7 0

5 0 1 0 9 0 5 0 1 0 9 0]

[DGM]

Either answer will zero-pad columns regardless of the size or contents of A.

If you're trying to describe a particular generalized relationship between input and output, you'll have to clarify with both inputs and outputs for your example.