From: Peter Munch <peterrmuench@gmail.com>
Date: Mon, 21 Jun 2021 14:37:23 +0000 (+0200)
Subject: Fix MinimalGranularityPolicy
X-Git-Tag: v9.4.0-rc1~1207^2
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f34825dff95daea6b217363becce2f2dd19291c3;p=dealii.git

Fix MinimalGranularityPolicy
---

diff --git a/source/distributed/repartitioning_policy_tools.cc b/source/distributed/repartitioning_policy_tools.cc
index d13b788d90..a7e35036f4 100644
--- a/source/distributed/repartitioning_policy_tools.cc
+++ b/source/distributed/repartitioning_policy_tools.cc
@@ -208,10 +208,17 @@ namespace RepartitioningPolicyTools
       // the same number of cells; if there is a remainder, we assign the
       // first processes an additional cell (so that the difference of number of
       // locally owned cells is never larger than one between processes).
-      if (i < (i / min_cells) * min_cells + (n_global_active_cells % min_cells))
-        return i / (min_cells + 1);
-      else
-        return (i - (n_global_active_cells % min_cells)) / min_cells;
+      const unsigned int n_partitions_with_additional_cell =
+        n_global_active_cells - min_cells * n_partitions;
+
+      const unsigned int rank =
+        (i < (min_cells + 1) * n_partitions_with_additional_cell) ?
+          (i / (min_cells + 1)) :
+          ((i - n_partitions_with_additional_cell) / min_cells);
+
+      AssertIndexRange(rank, n_partitions);
+
+      return rank;
     };
 
     for (const auto i : partition.locally_owned_elements())