From a906cb80b80dff83d2cfbdcf858bb6eac36b4aba Mon Sep 17 00:00:00 2001
From: prkkumar <prabhatams@gmail.com>
Date: Wed, 17 Jul 2024 12:23:42 -0700
Subject: [PATCH] remove set_slow_fast_timestep_ratio and add input file

---
 .../Exec/inputs_forward_euler                 | 14 -----------
 .../Reaction-Diffusion/Exec/inputs_rk3        | 24 -------------------
 .../{inputs_sundials => inputs_sundials_mri}  | 14 ++++++-----
 .../Reaction-Diffusion/Source/main.cpp        |  4 ----
 4 files changed, 8 insertions(+), 48 deletions(-)
 delete mode 100644 ExampleCodes/SUNDIALS/Reaction-Diffusion/Exec/inputs_forward_euler
 delete mode 100644 ExampleCodes/SUNDIALS/Reaction-Diffusion/Exec/inputs_rk3
 rename ExampleCodes/SUNDIALS/Reaction-Diffusion/Exec/{inputs_sundials => inputs_sundials_mri} (79%)

diff --git a/ExampleCodes/SUNDIALS/Reaction-Diffusion/Exec/inputs_forward_euler b/ExampleCodes/SUNDIALS/Reaction-Diffusion/Exec/inputs_forward_euler
deleted file mode 100644
index 39b09830..00000000
--- a/ExampleCodes/SUNDIALS/Reaction-Diffusion/Exec/inputs_forward_euler
+++ /dev/null
@@ -1,14 +0,0 @@
-n_cell = 32
-max_grid_size = 16
-
-nsteps = 1000
-plot_int = 100
-
-dt = 1.e-5
-
-# INTEGRATION
-## integration.type can take on the following values:
-## 0 or "ForwardEuler" => Native AMReX Forward Euler integrator
-## 1 or "RungeKutta"   => Native AMReX Explicit Runge Kutta controlled by integration.rk.type
-## 2 or "SUNDIALS"     => SUNDIALS backend controlled by integration.sundials.strategy
-integration.type = ForwardEuler
diff --git a/ExampleCodes/SUNDIALS/Reaction-Diffusion/Exec/inputs_rk3 b/ExampleCodes/SUNDIALS/Reaction-Diffusion/Exec/inputs_rk3
deleted file mode 100644
index 6eb60137..00000000
--- a/ExampleCodes/SUNDIALS/Reaction-Diffusion/Exec/inputs_rk3
+++ /dev/null
@@ -1,24 +0,0 @@
-n_cell = 32
-max_grid_size = 16
-
-nsteps = 1000
-plot_int = 100
-
-dt = 1.e-5
-
-# INTEGRATION
-## integration.type can take on the following values:
-## 0 or "ForwardEuler" => Native AMReX Forward Euler integrator
-## 1 or "RungeKutta"   => Native AMReX Explicit Runge Kutta controlled by integration.rk.type
-## 2 or "SUNDIALS"     => SUNDIALS backend controlled by integration.sundials.strategy
-integration.type = RungeKutta
-
-## Native AMReX Explicit Runge-Kutta parameters
-#
-## integration.rk.type can take the following values:
-### 0 = User-specified Butcher Tableau
-### 1 = Forward Euler
-### 2 = Trapezoid Method
-### 3 = SSPRK3 Method
-### 4 = RK4 Method
-integration.rk.type = 3
diff --git a/ExampleCodes/SUNDIALS/Reaction-Diffusion/Exec/inputs_sundials b/ExampleCodes/SUNDIALS/Reaction-Diffusion/Exec/inputs_sundials_mri
similarity index 79%
rename from ExampleCodes/SUNDIALS/Reaction-Diffusion/Exec/inputs_sundials
rename to ExampleCodes/SUNDIALS/Reaction-Diffusion/Exec/inputs_sundials_mri
index bbdf2c69..fed23dc7 100644
--- a/ExampleCodes/SUNDIALS/Reaction-Diffusion/Exec/inputs_sundials
+++ b/ExampleCodes/SUNDIALS/Reaction-Diffusion/Exec/inputs_sundials_mri
@@ -1,3 +1,4 @@
+##
 n_cell = 32
 max_grid_size = 16
 
@@ -6,6 +7,10 @@ plot_int = 100
 
 dt = 1.e-5
 
+# To replicate heat equation
+diffusion_coef = 1.0
+reaction_coef = 1.0
+
 # Use adaptive time stepping and set integrator relative and absolute tolerances
 # adapt_dt = true
 # reltol   = 1.0e-4
@@ -33,12 +38,9 @@ integration.type = SUNDIALS
 # documentation for the supported method names
 
 # Use the SUNDIALS default method for the chosen type (fixed or adaptive step sizes)
-integration.sundials.type = ERK
+integration.sundials.type = EX-MRI # all the types listed above work with respective default methods
 
-# Use forward Euler (fixed step sizes only)
+# The following combination of type and method works as well
 # integration.sundials.type = ERK
-# integration.sundials.method = ARKODE_FORWARD_EULER_1_1
+#integration.sundials.method = ARKODE_MRI_GARK_FORWARD_EULER #ARKODE_FORWARD_EULER_1_1
 
-# Use backward Euler (fixed step sizes only)
-# integration.sundials.type = DIRK
-# integration.sundials.method = ARKODE_BACKWARD_EULER_1_1
diff --git a/ExampleCodes/SUNDIALS/Reaction-Diffusion/Source/main.cpp b/ExampleCodes/SUNDIALS/Reaction-Diffusion/Source/main.cpp
index 4add8ebd..cda2385e 100644
--- a/ExampleCodes/SUNDIALS/Reaction-Diffusion/Source/main.cpp
+++ b/ExampleCodes/SUNDIALS/Reaction-Diffusion/Source/main.cpp
@@ -246,10 +246,6 @@ void main_main ()
         integrator.set_time_step(dt);
     }
 
-    // This sets the ratio of slow timestep size to fast timestep size as an integer,
-    // or equivalently, the number of fast timesteps per slow timestep.
-    integrator.set_slow_fast_timestep_ratio(10);
-
     for (int step = 1; step <= nsteps; ++step)
     {
         // Set time to evolve to