How to constructing a matrix of repeated rows v?

If I have an arbitrary matrix A and a row vector v of 1 row and the same number of columns as A.

Suppose I want to construct a matrix Q of the same size as A where every row in Q is the vector v.

Illustrative example:

A=[ 1 1 1; 2 2 2; 3 3 3; 4 4 4]; v=[5 5 5];

%I want to create Q s.t
Q=[5 5 5; 5 5 5 5; 5 5 5 5; 5 5 5 5];

Thanks

Answer 1

[Matt J]

Either of the following would work

>> Q=repelem(v,size(A,1),1)

>> Q=repmat(v,size(A,1),1)

but note that it's not normally something you need or want to do. Matlab has deliberately provided implicit expansion,

https://nhigham.com/2016/09/20/implicit-expansion-matlab-r2016b/

or for older Matlab versions bsxfun,

https://www.mathworks.com/help/matlab/ref/bsxfun.html

to avoid such copying in many common situations.