Add Rosenbrock methods

integration/ROS2S/Make.package

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+CEXE_headers += ros2s_type.H
+CEXE_headers += ros2s_integrator.H
+ifeq ($(USE_ALL_SDC), TRUE)
+  CEXE_headers += actual_integrator_sdc.H
+else
+  CEXE_headers += actual_integrator.H
+endif

integration/ROS2S/_parameters

@@ -0,0 +1,21 @@
+@namespace: integrator
+
+# for the step rejection logic on mass fractions, we only consider
+# species that are > X_reject_buffer * atol_spec
+X_reject_buffer              real         1.0
+
+# Rosenbrock tableau selector:
+#   0 = existing 3-stage ROS2S tableau
+#   1 = Verwer et al. (1999) 2-stage ROS2 tableau
+#   2 = Sandu (2000) positivity-favoring method A
+#   3 = Sandu (2000) positivity-favoring method B
+#   4 = Sandu (2000) positivity-favoring method C
+#   5 = Sandu (2000) positivity-favoring method D
+rosenbrock_tableau           int          0
+
+# H211b timestep controller parameters
+h211b_b                      real         4.0
+h211b_k                      real         2.5
+h211b_fac_min                real         0.2
+h211b_fac_max                real         6.0
+h211b_reduction_fac          real         0.5

integration/ROS2S/actual_integrator.H

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+#ifndef actual_integrator_H
+#define actual_integrator_H
+
+#include <AMReX_REAL.H>
+
+#include <network.H>
+#include <burn_type.H>
+
+#include <integrator_data.H>
+#include <integrator_setup_strang.H>
+#include <ros2s_integrator.H>
+#include <ros2s_type.H>
+
+template <typename BurnT>
+AMREX_GPU_HOST_DEVICE AMREX_INLINE
+void actual_integrator (BurnT& state, amrex::Real dt, bool is_retry=false)
+{
+    constexpr int int_neqs = integrator_neqs<BurnT>();
+
+    auto ros2s_state = integrator_setup<BurnT, ros2s_t<int_neqs>>(state, dt, is_retry);
+    auto state_save = integrator_backup(state);
+
+    int istate = ros2s_integrator(state, ros2s_state);
+
+    integrator_cleanup(ros2s_state, state, istate, state_save, dt);
+}
+
+#endif

integration/ROS2S/actual_integrator_sdc.H

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+#ifndef actual_integrator_H
+#define actual_integrator_H
+
+#include <AMReX_REAL.H>
+
+#include <network.H>
+#include <burn_type.H>
+
+#include <integrator_data.H>
+#include <integrator_setup_sdc.H>
+#include <ros2s_integrator.H>
+#include <ros2s_type.H>
+
+template <typename BurnT>
+AMREX_GPU_HOST_DEVICE AMREX_INLINE
+void actual_integrator (BurnT& state, amrex::Real dt, bool is_retry=false)
+{
+    constexpr int int_neqs = integrator_neqs<BurnT>();
+
+    auto ros2s_state = integrator_setup<BurnT, ros2s_t<int_neqs>>(state, dt, is_retry);
+    auto state_save = integrator_backup(state);
+
+    int istate = ros2s_integrator(state, ros2s_state);
+
+    integrator_cleanup(ros2s_state, state, istate, state_save, dt);
+}
+
+#endif