20210708_bobmyhill

New: ASPECT now has a ThermodynamicTableLookup
equation of state plugin. This plugin allows material models
to read in one or more Perple_X or HeFESTo table files,
interpolate material properties at desired pressures and
temperatures, and use the interpolated properties as
material model outputs. The equation of state plugin is
currently used in the Steinberger material model.
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(Bob Myhill, 2021/07/08)