• Type: Correctness / API misuse
• Severity: High
• Component: SUNDIALS MRI slow-step configuration
• Location:
  • Src/Extern/SUNDIALS/AMReX_SundialsIntegrator.H:414
  • Src/Extern/SUNDIALS/AMReX_SundialsIntegrator.H:417
  • Src/Extern/SUNDIALS/AMReX_SundialsIntegrator.H:427
  • Src/Extern/SUNDIALS/AMReX_SundialsIntegrator.H:441
  • Src/Extern/SUNDIALS/AMReX_SundialsIntegrator.H:446

Problem

After creating the slow integrator with MRIStepCreate, the code configures it via ARKStepSet* calls (nonlinear/linear solver, stop time, max steps).

Impact

• API calls may fail or not apply to MRIStep as intended.
• Slow MRI solver configuration may be incorrect in implicit IM/IMEX MRI modes.

Suggested patch

Use MRIStep-appropriate setters (or generic ARKode setters for all stepper types when available in the targeted SUNDIALS version).

--- a/Src/Extern/SUNDIALS/AMReX_SundialsIntegrator.H
+++ b/Src/Extern/SUNDIALS/AMReX_SundialsIntegrator.H
@@
-                flag = ARKStepSetNonlinearSolver(arkode_mem, NLS);
+                flag = MRIStepSetNonlinearSolver(arkode_mem, NLS);
@@
-            flag = ARKStepSetMaxNonlinIters(arkode_mem, max_nonlinear_iters);
+            flag = MRIStepSetMaxNonlinIters(arkode_mem, max_nonlinear_iters);
@@
-                flag = ARKStepSetLinearSolver(arkode_mem, LS, nullptr);
+                flag = MRIStepSetLinearSolver(arkode_mem, LS, nullptr);
@@
-          flag = ARKStepSetStopTime(arkode_mem, stop_time);
+          flag = MRIStepSetStopTime(arkode_mem, stop_time);
@@
-        flag = ARKStepSetMaxNumSteps(arkode_mem, max_num_steps);
+        flag = MRIStepSetMaxNumSteps(arkode_mem, max_num_steps);

Prepared by Codex