repmat vs simple matrix multiplication in MATLAB

Question

Let v be a row vector of length n. The goal is to create a matrix A with m rows that are all equal to v.

MATLAB has a function for this that is

Answer 1

Lets compare them!

When testing algorithms 2 metrics are important: time, and memory.

Lets start with time:

Clearly repmat wins!

Memory:

profile -memory on
for m=1000:1000:50000
f1=@()(repmat(v,[m 1]));
f2=@()(ones(m,1)*v);
ii=ii+1;
t1(ii)=timeit(f1);
t2(ii)=timeit(f2);
end
profreport

It seems that both take the same amount of memory. However, the profiler is known for not showing all the memory, so we can not fully trust it.

Still, it is clear that repmat is better