make eigen2 cholesky test pass

Eigen/src/Cholesky/LLT.h

@@ -135,6 +135,17 @@ template<typename _MatrixType, int _UpLo> class LLT
       return internal::solve_retval<LLT, Rhs>(*this, b.derived());
     }
 
+    #ifdef EIGEN2_SUPPORT
+    template<typename OtherDerived, typename ResultType>
+    bool solve(const MatrixBase<OtherDerived>& b, ResultType *result) const
+    {
+      *result = this->solve(b);
+      return true;
+    }
+    
+    bool isPositiveDefinite() const { return true; }
+    #endif
+
     template<typename Derived>
     void solveInPlace(MatrixBase<Derived> &bAndX) const;