The plus(M1,M2) function performs matrix addition of M1 + M2.  If M1 is a scalar, then M1 is added to each element of M2.

Arrays M1 and M2 must be the same size.

$\mathrm{with}\left(\mathrm{MTM}\right)\:$

$\mathrm{M1}≔\mathrm{Matrix}\left(2\,3\,'\mathrm{fill}'=1\right)\:$

$\mathrm{M2}≔\mathrm{Matrix}\left(2\,3\,'\mathrm{fill}'=2\right)\:$

$\mathrm{plus}\left(\mathrm{M1}\,\mathrm{M2}\right)$

$\left[\begin{array}{ccc}3& 3& 3\\ 3& 3& 3\end{array}\right]$