Polynomial representations extrapolation

Extrapolation might not be reasonable, which is often the case for polynomials. Therefore, a graphical representation showing the whole temperature range of interest should be checked to obtain a reasonable curvature. 

There are two ways to handle the task of representing properties of individual species. In the first one the properties of the substances are provided in a tabular form at predetermined temperature intervals and the values needed are calculated by interpolation. This method requires large memory storage, handling thousands of thermodynamic values, and does not permit use beyond the temperature limits of the table. A second and more commonly used technique is representation of the properties of each species by polynomials that allow direct calculation of the thermodynamic properties at any temperature, including limited extrapolation beyond the fitted range of the polynomial. 

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