binary is used to constrain a variable to be binary.
Syntax
F = binary(x)
Examples
Setting up a binary linear program {min cTx subject to Ax≤b} can be done as
x = binvar(n,1);
solvesdp(A*x<b,c'*x)
solvesdp(A*x<b,c'*x)
or
x = sdpvar(n,1);
solvesdp([A*x<=b, binary(x)],c'*x)
solvesdp([A*x<=b, binary(x)],c'*x)
The binary constraint is imposed on the involved variables, not the actual sdpvar object. Hence, the following two constraints are equivalent
F = binary(x);
F = binary(pi+sqrt(2)*x);
F = binary(pi+sqrt(2)*x);
Comment
If possible, use binvar instead.