Cvx_begin set sdp

Hello!
I saw some code that used CVX to solve the problem, but I don’t know what this code "cvx_begin set sdp " means.Is that what it means to build a collection?Can you explain the meaning of this code for me?
Thank,you!

cvx_begin sdp
invokes SDP mode http://cvxr.com/cvx/doc/sdp.html

cvx_begin set sdp
is not documented in the CVX Users’ Guide. But it does not produce an error message. But gave me an error when I provided a minimize statement

Error using cvxprob/newobj (line 24)
An objective has already been supplied for this problem.

So I don’t know what cvx_begin set sdp actually does, and I don’t recommend using it. However, it is fine to use cvx_begin sdp, as documented in the above link.

Thank you for your answer.