How can I concatenate two or more arrays without using num2str?

For example if I have two vertical arrays:

A = [1;2] B = [3;4]

I need this output:

C = [13; 24]

The problem is that my arrays have many rows, thus num2str is too slow. What can I do? Thanks!!!

[Adam]

I can't help but think of the joke of someone asking for directions to somewhere and being told 'Well, if I were you I wouldn't start from here'.

There may be better suggestions based on the wider context of the code than already having A and B defined.

[John D'Errico]

Good response by Adam.

Answer 1

[John D'Errico]

The most obvious solution is to appreciate how a number is constructed in decimal form. So, rather than convert to characters, then concatenate, and then go back in to numeric form, simply use base 10.

C = 10*A + B;

[Guillaume]

And a generic version of that for integers of any (reasonable) magnitude:

C = A .* 10.^ceil(log10(B)) + B

[John D'Errico]

True. I expect that whenever I see an example with one digit integers, the real problem is always more complex. :)

[Walter Roberson]

I would max(1,log10(max(abs(B))))

though the desired outcome is not clear for negative values.

Answer 2

[Adriano]

Many thanks!!!!