How to 'stretch' a matrix using a loop?

Hi,

I have a 252x252 distance matrix. Now I need to reshape this matrix into a 3528x3528 matrix: so rows and columns times 14. I want the first 14 rows and columns, so a matrix of 1:14,1:14, filled with the first cell in the old matrix.

So Dnew 1:14,1:14 = Dold 1,1 Dnew 15:28,1:14 = Dold 2,1 D new 1:14,15:28 = Dold 1,2

How do I program this using a loop? Since I need to repeat it for every 1:14,1:14 matrix within my 3528x3528 matrix.

Thanks

Answer 1

[Stephen23]

R2015a or later: use repelem:

repelem(M,14,14)

Earlier versions: use kron:

kron(M,ones(14))

[Roos de Bruijn]

Thanks, but how do I repeat this for 63504 elements?

When I fill out Dnew60 = repelem(distancematrix,[14,14])

it does not work.

[Stephen23]

See my edited answer. In any case, this "works" for me:

>> M = rand(252,252);
>> N = kron(M,ones(14));
>> size(N)
ans =
        3528        3528

And, according to the repelem documentation which I just read, this should work for a matrix M:

   repelem(M,14,14)

Answer 2

[John BG]

Hi Roos the Bruijin

this is John BG( <mailto:[e-mail] [e-mail]> )

the repelem syntax that you should be using is

repelem(Dold,2,14,14)

or simply

repelem(Dold,14,14)

the command repelem does not accept the syntax

repelem(Dold,[14 14])

suggested by Mr Cobeldick:

Another MATLAB improvement:

now one can directly run commands in the Internet browser, try it by opening this link

https://uk.mathworks.com/help/matlab/ref/repelem.html?s_tid=srchtitle

.

if you find this answer useful would you please be so kind to consider marking my answer as Accepted Answer?

To any other reader, if you find this answer useful please consider clicking on the thumbs-up vote link

thanks in advance

John BG

<mailto:[e-mail] [e-mail]>

[Stephen23]

@John BG: thank you for pointing out the small error in my code, I have corrected it. On this forum it is certainly appreciated when others kindly point out simple and obvious syntax errors in a comment.

It is also appreciated when one takes the time to spell people's names correctly.

[John BG]

thanks Mr Cobeldick, duly noted