From da6fb4c5443d72e790484e63a23e3e9b4e272860 Mon Sep 17 00:00:00 2001
From: Aidan Thompson <athomps@sandia.gov>
Date: Fri, 8 Apr 2022 15:47:12 -0600
Subject: [PATCH] Added epsilon shift to eliminate uneven tiebreaks

---
 src/compute_grid_local.cpp | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/src/compute_grid_local.cpp b/src/compute_grid_local.cpp
index 1b8de3c48a..e99a742c3b 100644
--- a/src/compute_grid_local.cpp
+++ b/src/compute_grid_local.cpp
@@ -191,6 +191,19 @@ void ComputeGridLocal::set_grid_local()
     zfrachi = comm->mysplit[2][1];
   }
 
+  // not fully clear why this works
+  // without, sometimes get uneven assignments
+  // in case where ngridz is multiple of nprocz
+
+  double MYEPS = 1.0e-10;
+
+  xfraclo += MYEPS;
+  xfrachi += MYEPS;
+  yfraclo += MYEPS;
+  yfrachi += MYEPS;
+  zfraclo += MYEPS;
+  zfrachi += MYEPS;
+
   nxlo = static_cast<int> (xfraclo * nx);
   if (1.0*nxlo != xfraclo*nx) nxlo++;
   nxhi = static_cast<int> (xfrachi * nx);