+ True
+
+ However, this matrix has a negative eigenvalue:
+
+ >>> K = SymmetricPSD(2)
+ >>> A = matrix([[ 1, -2],
+ ... [-2, 1]])
+ >>> A in K
+ False
+
+ An asymmetric cone with positive eigenvalues is not in the cone:
+
+ >>> K = SymmetricPSD(2)
+ >>> A = matrix([[10, 2],
+ ... [4, 8]])
+ >>> A in K
+ False