This function iteratively determines the saturation state for a
given temperature by varying the density of saturated liquid and
saturated vapor with a Newton-Raphson approach for simultaneous
equations.
Ryo Akasaka:
A reliable and useful method to determine the saturation
state from Helmholtz energy equations of state.
Journal of Thermal Science and Technology 3 (3) , 442-451.
DOI: 10.1299/jtst.3.442