This software implements the model of Tait, Jaupart and Vergniolle (1989), which addresses the pressure variations produced by a partial crystallization of a magmatic chamber.

The input data are:

- the initial conditions: temperature, pressure, volatiles composition (H2O, CO2), volatiles and solid mass proportions.
- the final weight proportion of solids in the magma.

It calculates:

- the overpressure (or underpressure) induced by the partial solidification of the magma
- the mass and volume proportions of the different phases (gas, melt, solids) in the magma.