The conj(M) function computes the element-wise conjugate of M.  The result, R, is formed as R[i,j] = conj(M[i,j]).

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

$M≔\mathrm{Matrix}\left(2\,3\,'\mathrm{fill}'=-3+\mathrm{I}\right)\:$

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

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