Calculates superheated steam properties based on the steam tables, IF97 formulation (IAPWS-IF97).
Returns properties at the state point $(T,P)$ — enthalpy, entropy, and specific heat—plus $P_{sat}(T)$ and $T_{sat}(P)$ for reference and superheat checking.
Thermodynamic functions are evaluated directly: $$ h = h(T,P), \quad s = s(T,P), \quad c_p = c_p(T,P). $$