This record includes the C++ files used to generate superancillary equations (sets of Chebyshev expansions for the co-existing thermodynamic data) for the multiparameter EOS included in NIST REFPROP 10.0. The calculations in C++ are done in extended precision and the Chebyshev expansions are stored in double precision. The python scripts are used to post-process the generated sets of Chebyshev expansions. The advantage of this methodology is that the phase equilibrium calculations can be entirely avoided, resulting a computational speedup on the order of a factor of hundreds of times, without sacrificing any accuracy,

Additional information is available in the README file.

The working code is at https://github.com/usnistgov/fastchebpure