Summary

Corrects Set function calls to configure the slow integrator with an implicit MRI method. This addresses the issues noted in #5044. The calls changed from ARKStep to MRIStep would work with SUNDIALS 7.1.0 or newer (when stepper specific Set functions were deprecated and replaced with common ARKode functions) but would fail with earlier versions of SUNDIALS.

Correct Set functions calls to configure an implicit fast integrator in an MRI method to use a fixed-point solver, modify the max number of iterations, or set the linear solver when using a Newton solver.

Additional background

Checklist

The proposed changes:

• fix a bug or incorrect behavior in AMReX
• add new capabilities to AMReX
• changes answers in the test suite to more than roundoff level
• are likely to significantly affect the results of downstream AMReX users
• include documentation in the code and/or rst files, if appropriate