if i have the following optimization problem the variable is only Wtc: minimize( norm(y_r-H*Wtc,'fro')+norm(f - pinv(Pq)*vec(Wr1*G*Wtc'*Wtc)),'fro')) to over come the multiplication of Wtc'*Wtc i used the following minimize( norm(y_r-H*Wtc,'fro')+norm(f - pinv(Pq)*vec(Wr1*G*quad_form(Wtc, eye(Nt))),'fro'))
but the cvx give the following error Error using .*
Disciplined convex programming error:
Cannot perform the operation: {complex affine} .* {convex}

Error in * (line 36)
z = feval( oper, x, y );

Error in solv_z_problem_SU (line 61)
minimize( norm(y_r-HWtc,‘fro’)+norm(f - pinv(Pq)vec(Wr1Gquad_form(Wtc, eye(Nt))),‘fro’))

the problem in general is minimize( norm(y_r-H*Wtc,'fro')+norm(f - pinv(Pq)*vec(Wr1*G*Wt)),'fro')) where Wt = Wtc'*Wtc as far as i know both are norm and convex the first norm is convex with respect to Wtc and the second norm is convex with respect to Wt but the problem appears when Wt=Wtc'*Wtc by the wat Wtc is vector (N,1) and Wt is matrix (N,N). Thus i want to include Wt=Wtc'*Wtc for problem and maintain the convexity.