The function \(qre(X,Y):=\text{TR}(X\ln(X)- X\ln(Y))\) is a convex function, with epigraph \[ \{(t,X,Y) \in \mathbb R\oplus \mathbb S^n \oplus \mathbb S^n: \text{TR}(X\ln(X)-X\ln(Y)) \leq t\}. \] DDS 2.0 uses the following barrier (not yet known to be s.c.) for solving problems involving quantum relative entropy constraints: \[ \Phi(t,X,Y):= \ln(t - qre(X,Y)) - \ln \det(X) - \ln \det(Y). \] To see how to add GRE contraints, please see the users' guide.