Can anyone help me with this problem?

I am trying to solve problems using CVX. My code is

variable k
variable D(m, n)
minimize(norm(k*eye(n)-D’*D, ‘fro’));

subject to


I got the error: Only scalar quadratic forms can be specified in CVX. I know the problem is D’*D. But I don’t know how to rewrite it in DCP rules. Can anyone help me with that, thanks very much!

This is non-convex. Therefore, it can not be rewritten in compliance with DCP rules.