concatenate all value in a matrix into one number

if I have a matrix [1 2 3 4], is there a quick and easy way to obtain 1234 ?

Answer 1

[Thorsten]

This works even if the numbers are not single digits, i.e., in in {1,2,...,9}

 v = [10 20 4]; 
 num = sscanf(sprintf('%d', v), '%f')

[Guillaume]

Indeed, however if they are single digits (as I assumed), conversion to string and back to number is going to be several order of magnitude slower than simple mathematical manipulation.

Not that it matters for such trivial code.

Answer 2

[Guillaume]

v = [1 2 3 4];
assert(all(v >= 0 & v < 10 & mod(v, 1) == 0), 'elements of v are not single digits');
sum(10.^(numel(v)-1:-1:0) .* v)