From 121dec771b073b2bba102361e0c3af451947481c Mon Sep 17 00:00:00 2001
From: David Wells <drwells@email.unc.edu>
Date: Tue, 7 Jun 2022 15:24:07 -0400
Subject: [PATCH] Make all ARKODE implicit test functions linear.

Forcing functions don't effect stability so they should always be in the
explicit part.
---
 tests/sundials/arkode_03.cc | 4 ++--
 tests/sundials/arkode_04.cc | 4 ++--
 tests/sundials/arkode_05.cc | 4 ++--
 tests/sundials/arkode_06.cc | 4 ++--
 tests/sundials/arkode_07.cc | 4 ++--
 5 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/tests/sundials/arkode_03.cc b/tests/sundials/arkode_03.cc
index 9fbdccae8a..b6a54046b0 100644
--- a/tests/sundials/arkode_03.cc
+++ b/tests/sundials/arkode_03.cc
@@ -76,7 +76,7 @@ main()
     [&](double, const VectorType &y, VectorType &ydot) -> int {
     ydot[0] = 0;
     ydot[1] = 0;
-    ydot[2] = (b - y[2]) / eps;
+    ydot[2] = -y[2] / eps;
     return 0;
   };
 
@@ -85,7 +85,7 @@ main()
     [&](double, const VectorType &y, VectorType &ydot) -> int {
     ydot[0] = a - (y[2] + 1) * y[0] + y[1] * y[0] * y[0];
     ydot[1] = y[2] * y[0] - y[1] * y[0] * y[0];
-    ydot[2] = -y[2] * y[0];
+    ydot[2] = b / eps - y[2] * y[0];
     return 0;
   };
 
diff --git a/tests/sundials/arkode_04.cc b/tests/sundials/arkode_04.cc
index 4b2d0b4891..1f5a284e1d 100644
--- a/tests/sundials/arkode_04.cc
+++ b/tests/sundials/arkode_04.cc
@@ -79,7 +79,7 @@ main()
     [&](double, const VectorType &y, VectorType &ydot) -> int {
     ydot[0] = 0;
     ydot[1] = 0;
-    ydot[2] = (b - y[2]) / eps;
+    ydot[2] = -y[2] / eps;
     return 0;
   };
 
@@ -88,7 +88,7 @@ main()
     [&](double, const VectorType &y, VectorType &ydot) -> int {
     ydot[0] = a - (y[2] + 1) * y[0] + y[1] * y[0] * y[0];
     ydot[1] = y[2] * y[0] - y[1] * y[0] * y[0];
-    ydot[2] = -y[2] * y[0];
+    ydot[2] = b / eps - y[2] * y[0];
     return 0;
   };
 
diff --git a/tests/sundials/arkode_05.cc b/tests/sundials/arkode_05.cc
index 526eb7fc22..40d320f6d8 100644
--- a/tests/sundials/arkode_05.cc
+++ b/tests/sundials/arkode_05.cc
@@ -78,7 +78,7 @@ main()
     [&](double, const VectorType &y, VectorType &ydot) -> int {
     ydot[0] = 0;
     ydot[1] = 0;
-    ydot[2] = (b - y[2]) / eps;
+    ydot[2] = -y[2] / eps;
     return 0;
   };
 
@@ -87,7 +87,7 @@ main()
     [&](double, const VectorType &y, VectorType &ydot) -> int {
     ydot[0] = a - (y[2] + 1) * y[0] + y[1] * y[0] * y[0];
     ydot[1] = y[2] * y[0] - y[1] * y[0] * y[0];
-    ydot[2] = -y[2] * y[0];
+    ydot[2] = b / eps - y[2] * y[0];
     return 0;
   };
 
diff --git a/tests/sundials/arkode_06.cc b/tests/sundials/arkode_06.cc
index ba1a619afc..35908ec72c 100644
--- a/tests/sundials/arkode_06.cc
+++ b/tests/sundials/arkode_06.cc
@@ -85,7 +85,7 @@ main()
     [&](double, const VectorType &y, VectorType &ydot) -> int {
     ydot[0] = 0;
     ydot[1] = 0;
-    ydot[2] = (b - y[2]) / eps;
+    ydot[2] = -y[2] / eps;
     return 0;
   };
 
@@ -94,7 +94,7 @@ main()
     [&](double, const VectorType &y, VectorType &ydot) -> int {
     ydot[0] = a - (y[2] + 1) * y[0] + y[1] * y[0] * y[0];
     ydot[1] = y[2] * y[0] - y[1] * y[0] * y[0];
-    ydot[2] = -y[2] * y[0];
+    ydot[2] = b / eps - y[2] * y[0];
     return 0;
   };
 
diff --git a/tests/sundials/arkode_07.cc b/tests/sundials/arkode_07.cc
index 57779f7bab..b9cd3ad97a 100644
--- a/tests/sundials/arkode_07.cc
+++ b/tests/sundials/arkode_07.cc
@@ -85,7 +85,7 @@ main()
     [&](double, const VectorType &y, VectorType &ydot) -> int {
     ydot[0] = 0;
     ydot[1] = 0;
-    ydot[2] = (b - y[2]) / eps;
+    ydot[2] = -y[2] / eps;
     return 0;
   };
 
@@ -94,7 +94,7 @@ main()
     [&](double, const VectorType &y, VectorType &ydot) -> int {
     ydot[0] = a - (y[2] + 1) * y[0] + y[1] * y[0] * y[0];
     ydot[1] = y[2] * y[0] - y[1] * y[0] * y[0];
-    ydot[2] = -y[2] * y[0];
+    ydot[2] = b / eps - y[2] * y[0];
     return 0;
   };
 
-- 
2.39.5