how to chage/replace the one matrix value into another matrix value

for it=1:6144
    cd(it)=cdt(it);
end

Answer 1

[KSSV]

   cd=cdt

[Jan]

+1 :-) Surpringly easy, but exhaustively correct.

Perhaps the question concerns a part of the matrix only. Then:

cd(1:6144) = cdt(1:6144);