Investigations of approximation formulas for table equations of state in variables temperature-density

EQSs are assumed to be presented in form of table dependence of pressure and inner energy from temperature and density. A investigation of robustness of approximation formulas is carried out. The role of Jacobean of EQS turns out to be significant. The conditions that should be proved to provide its nonsingularity are formulated. The problems of control of tables that present initial data and issues of practical realization suggested algorithms are considered.