Well, I do it like this:
function [Amin, Amax] = minmax( A )
Amin = min(A);
Amax = max(A);
Note: Not to be confused with minimax algorithm!
You could beef it up if necessary to handle the different inputs and outputs of min and max.
But this may be all you need. I admit it is using min and max separately, but your calling code doesn't care. I don't know of a native function that does this. It is only marginally less efficient than any code that could be written to find both at once.