How to get the optimal value(cvx_optval)?

I want to solve the feasibility problem, and I will judge the feasibility of the problem according to the optimal value obtained by CVX. The optimal value(cvx_optval) is zero means the problem is feasible(as shown in illustration). But I don’t know how to get the optimal value(cvx_optval). Is there some matlab’s command to do that?

Type at the command line
cvx_optval

Or save it to a MATLAB variable:
cvx_optval_saved_value = cvx_optval;

Thanks for your reply! You give me lots of help!