SOLVE_NIVP

Recently, I had the pleasure to be able to help peer review the research software package solve_nivp released as a print on the Journal of Open Source Software (JOSS),
LINK (need to fix this haha)

Package purpose

solve_nivp is a Python library for time integration of nonsmooth ODE/DAE models: systems with abrupt changes such as impacts, switching, or inequality constraints. Such models are widespread: frictional contact in mechanics, piecewise and switching behaviour in circuits, sliding–mode control, and discontinuous rules in finance and energy markets [@brogliato2016nonsmooth; @acary2008numerical; @bernardo2008piecewise; @ShtesselEdwardsFridmanLevant2014; @Tramontana2010; @gabriel2012complementarity].

Classical solvers, which assume smoothness, often require heavy regularisation or very small steps due to the inherent stiffness of these models. solve_nivp builds nonsmooth rules directly into the implicit time-stepping scheme, enabling users to encode constraints and advance the state robustly. Documentation, examples, and tests accompany the code for reproducible use.

Review process

details to come…

Conclusion

Thank you to David Riley and Ioannis Stefanou for the wonderful software package with such an interesting use, and thank you to Daniel S. Katz for inviting me as co-Reviewer on this submission.