hases considering the 
%                            gas-to-liquid density ratio.
% * *compressibilityCoeffs*: Computes the compressibility coefficients for
%                            the liquid and gas phases based on the liquid 
%                            saturation degree Sl, liquid pressure pl, 
%                            and gas pressure pg.
% * *compressibilityCoeffsPgPc*: Computes the compressibility coefficients
%                                considering the gas-to-liquid 
%                  