Write a function $C=$ myMatSum $(A,B)$ that computes the sum of two matrices A and $B$ explicitly $($use a while loop and a for loop$).$ It should output an error message when the sizes of the matrices don't match. For example:

$myMa\frac{t}{S}um(\left[\begin{array}{cccc}1& 2\text{;}& 3& 4\end{array}\right],\left[\begin{array}{cccc}4& 3& 2& 1\end{array}\right])$

Error using myMatSum

Arrays have incompatible sizes for this operation.

$$ myMatSum$([12$; $34],[43$; $21])$

ans $=$

$5,5$

$5-5$