IAPWS95 refers to the Revised Release on the "Formulation 1995 for the Thermodynamic Properties of Ordinary Water Substance for General and Scientific Use" (September 2009) as published on the website www.iapws.org of the International Association for the Properties of Water and Steam.
The names of the various constants were transferred to valid MathCad variable names with minor modifications. Details and parameter values can be found in the document:
http://www.iapws.org/relguide/IAPWS95-Rev.pdf (Ref.1)
Solution:
The pressure can easily be calculated using the following function (Ref.1, Table 3) :
Expressions for further properties are given in Ref.1, Table 3. Analytical derivatives are reported in Ref.1, Tables 4 and 5.