ret = zeros(m, n);
for i = 1:m
    for j = 1:n
        ret(i, j) = some_function([i, j]);
    end
end

f[x_, y_] := y*x^2

SparseArray[{i_, j_} :> f[i, j], {3, 3}] // Normal

Array[f, {3, 3}]

Table[f[x, y], {x, 3}, {y, 3}]

(*
{{1, 2, 3}, {4, 8, 12}, {9, 18, 27}}

{{1, 2, 3}, {4, 8, 12}, {9, 18, 27}}

{{1, 2, 3}, {4, 8, 12}, {9, 18, 27}}