define transpose(m) -> res;
    lvars bl = boundslist(m);
    if length(bl) /= 4 then
        throw([need_2d_array ^a])
    endif;
    lvars i, i0 = bl(1), i1 = bl(2);
    lvars j, j0 = bl(3), j1 = bl(4);
    newarray([^j0 ^j1 ^i0 ^i1], 0) -> res;
    for i from i0 to i1 do
        for j from j0 to j1 do
            m(i, j) -> res(j, i);
        endfor;
    endfor;
enddefine;