The asterisk operator, '*', performs matrix multiplication, and as such, the
dimensions of it operands must be compatible, i.e. A * B  is valid if A is
m-by-n and B is n-by-p, the result is of size m-by-p.

The array multiply operator, '.*', as well as all other dyadic operators,
performs its operation element-by-element, so both of the operands must have
the same dimensions or be scalar.

Scalars may be used in combination with matrices in any expressions, e.g. 5 + A
adds 5 to every element of A if A is a matrix or vector.