(), <a href="unsupported/group__MatrixFunctions__Module.html">MatrixFunctions Module</a>       */     EIGEN_DEVICE_FUNC     MatrixType operatorSqrt() const     {       eigen_assert(m_isInitialized && "SelfAdjointEigenSolver is not initialized.");       eigen_assert(m_eigenvectorsOk && "The eigenvectors have not been computed together with the eigenvalues.");       return m_eivec * m_eivalues.cwiseSqrt().asDiagonal() * m_eivec.adjoint();     }      /** \brief 