The log2(M) function computes the element-wise base-2 logarithm of M.  The result, R, is formed as R[i,j] = log2(M[i,j]).

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

$M≔\mathrm{Matrix}\left(\left[\left[0.3\,0.2\right]\,\left[0.1\,0.4\right]\right]\right)\:$

$\mathrm{log2}\left(M\right)$

$\left[\begin{array}{cc}\mathrm{-1.736965594}& \mathrm{-2.321928095}\\ \mathrm{-3.321928095}& \mathrm{-1.321928095}\end{array}\right]$