The expm(A) command returns the matrix exp(A * t) = I + A * t + 1/2! * A^2 * t^2 + ... where I is the identity matrix.

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

$A≔\mathrm{Matrix}\left(\left[\left[1\,2\right]\,\left[2\,4\right]\right]\right)$

$A≔\left[\begin{array}{cc}1& 2\\ 2& 4\end{array}\right]$

$\mathrm{expm}\left(A\right)$

$\left[\begin{array}{cc}\frac{4}{5}+\frac{{\ⅇ}^5}{5}& \frac{2{\ⅇ}^5}{5}-\frac{2}{5}\\ \frac{2{\ⅇ}^5}{5}-\frac{2}{5}& \frac{1}{5}+\frac{4{\ⅇ}^5}{5}\end{array}\right]$