From 82a246de6d5cc557cd3fe34da564caf226d8bf99 Mon Sep 17 00:00:00 2001
From: Charles Kawczynski <kawczynski.charles@gmail.com>
Date: Thu, 28 Sep 2023 13:49:33 -0700
Subject: [PATCH] Unfuse hard-coded ARS updates

---
 src/time_stepper/hc_ars343.jl | 58 +++++++++++++++++------------------
 1 file changed, 28 insertions(+), 30 deletions(-)

diff --git a/src/time_stepper/hc_ars343.jl b/src/time_stepper/hc_ars343.jl
index 05493440b7..8df75c06dc 100644
--- a/src/time_stepper/hc_ars343.jl
+++ b/src/time_stepper/hc_ars343.jl
@@ -32,7 +32,8 @@ function CTS.step_u!(
 
     i = 2
     t_exp = t + dt * c_exp[i]
-    @. U = u + dt * a_exp[i, 1] * T_lim[1]
+    @. U = u
+    @. U += dt * a_exp[i, 1] * T_lim[1]
     lim!(U, p, t_exp, u)
     @. U += dt * a_exp[i, 1] * T_exp[1]
     dss!(U, p, t_exp)
@@ -70,12 +71,13 @@ function CTS.step_u!(
 
     i = 3
     t_exp = t + dt * c_exp[i]
-    @. U = u + dt * a_exp[i, 1] * T_lim[1] + dt * a_exp[i, 2] * T_lim[2]
+    @. U = u
+    @. U += dt * a_exp[i, 1] * T_lim[1]
+    @. U += dt * a_exp[i, 2] * T_lim[2]
     lim!(U, p, t_exp, u)
-    @. U +=
-        dt * a_exp[i, 1] * T_exp[1] +
-        dt * a_exp[i, 2] * T_exp[2] +
-        dt * a_imp[i, 2] * T_imp[2]
+    @. U += dt * a_exp[i, 1] * T_exp[1]
+    @. U += dt * a_exp[i, 2] * T_exp[2]
+    @. U += dt * a_imp[i, 2] * T_imp[2]
     dss!(U, p, t_exp)
     post_explicit!(U, p, t_exp)
 
@@ -110,18 +112,16 @@ function CTS.step_u!(
     T_exp!(T_exp[i], U, p, t_exp)
     i = 4
     t_exp = t + dt
-    @. U =
-        u +
-        dt * a_exp[i, 1] * T_lim[1] +
-        dt * a_exp[i, 2] * T_lim[2] +
-        dt * a_exp[i, 3] * T_lim[3]
+    @. U = u
+    @. U += dt * a_exp[i, 1] * T_lim[1]
+    @. U += dt * a_exp[i, 2] * T_lim[2]
+    @. U += dt * a_exp[i, 3] * T_lim[3]
     lim!(U, p, t_exp, u)
-    @. U +=
-        dt * a_exp[i, 1] * T_exp[1] +
-        dt * a_exp[i, 2] * T_exp[2] +
-        dt * a_exp[i, 3] * T_exp[3] +
-        dt * a_imp[i, 2] * T_imp[2] +
-        dt * a_imp[i, 3] * T_imp[3]
+    @. U += dt * a_exp[i, 1] * T_exp[1]
+    @. U += dt * a_exp[i, 2] * T_exp[2]
+    @. U += dt * a_exp[i, 3] * T_exp[3]
+    @. U += dt * a_imp[i, 2] * T_imp[2]
+    @. U += dt * a_imp[i, 3] * T_imp[3]
     dss!(U, p, t_exp)
     post_explicit!(U, p, t_exp)
 
@@ -159,20 +159,18 @@ function CTS.step_u!(
     i = -1
 
     t_final = t + dt
-    @. temp =
-        u +
-        dt * b_exp[2] * T_lim[2] +
-        dt * b_exp[3] * T_lim[3] +
-        dt * b_exp[4] * T_lim[4]
+    @. temp = u
+    @. temp += dt * b_exp[2] * T_lim[2]
+    @. temp += dt * b_exp[3] * T_lim[3]
+    @. temp += dt * b_exp[4] * T_lim[4]
     lim!(temp, p, t_final, u)
-    @. u =
-        temp +
-        dt * b_exp[2] * T_exp[2] +
-        dt * b_exp[3] * T_exp[3] +
-        dt * b_exp[4] * T_exp[4] +
-        dt * b_imp[2] * T_imp[2] +
-        dt * b_imp[3] * T_imp[3] +
-        dt * b_imp[4] * T_imp[4]
+    @. u = temp
+    @. u += dt * b_exp[2] * T_exp[2]
+    @. u += dt * b_exp[3] * T_exp[3]
+    @. u += dt * b_exp[4] * T_exp[4]
+    @. u += dt * b_imp[2] * T_imp[2]
+    @. u += dt * b_imp[3] * T_imp[3]
+    @. u += dt * b_imp[4] * T_imp[4]
     dss!(u, p, t_final)
     post_explicit!(u, p, t_final)
     return u