From ccf79edeb1abf5a8c144586ec5cf3c14bbe4bc25 Mon Sep 17 00:00:00 2001
From: oscarddssmith <oscar.smith@juliacomputing.com>
Date: Wed, 15 May 2024 11:02:19 -0400
Subject: [PATCH] only bail out as instable when dt is small or error is
 somewhat controlled

---
 src/integrator_interface.jl | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/src/integrator_interface.jl b/src/integrator_interface.jl
index 00424ffbc..9593baeb4 100644
--- a/src/integrator_interface.jl
+++ b/src/integrator_interface.jl
@@ -619,10 +619,15 @@ function check_error(integrator::DEIntegrator)
     end
     if integrator.opts.unstable_check(integrator.dt, integrator.u, integrator.p,
         integrator.t)
-        if integrator.opts.verbose
-            @warn("Instability detected. Aborting")
+        bigtol = max(integrator.opts.reltol, integrator.opts.abstol)
+        # only declare instability if the dt is very small
+        # or we have at least one digit of accuracy in the solution
+        if integrator.dt<eps(integrator.t) || isdefined(integrator, :EEst) && integrator.EEst * bigtol < .1
+            if integrator.opts.verbose
+                @warn("Instability detected. Aborting")
+            end
+            return ReturnCode.Unstable
         end
-        return ReturnCode.Unstable
     end
     if last_step_failed(integrator)
         if integrator.opts.verbose