From: Wolfgang Bangerth <bangerth@colostate.edu>
Date: Mon, 7 Jun 2021 15:38:28 +0000 (-0600)
Subject: Simplify the code that leads to an assertion.
X-Git-Tag: v9.4.0-rc1~1264^2
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7ecec249bbbc6ca1751e82062153ffc096ef7d3d;p=dealii.git

Simplify the code that leads to an assertion.

We convert integers to doubles so that we can run MPI::MinMaxAvg and then compare
the min against the max. We do this comparison with a tolerance, but that is
unnecessary: If the integer representations are the same, then so are the
floating point representations, bit-by-bit.
---

diff --git a/source/lac/trilinos_vector.cc b/source/lac/trilinos_vector.cc
index 53b4a28fc1..6a72c82a5d 100644
--- a/source/lac/trilinos_vector.cc
+++ b/source/lac/trilinos_vector.cc
@@ -616,13 +616,14 @@ namespace TrilinosWrappers
       // check that every process has decided to use the same mode. This will
       // otherwise result in undefined behavior in the call to
       // GlobalAssemble().
-      double                double_mode = mode;
+      const double          double_mode = mode;
       const Epetra_MpiComm *comm_ptr =
         dynamic_cast<const Epetra_MpiComm *>(&(trilinos_partitioner().Comm()));
       Assert(comm_ptr != nullptr, ExcInternalError());
-      Utilities::MPI::MinMaxAvg result =
+
+      const Utilities::MPI::MinMaxAvg result =
         Utilities::MPI::min_max_avg(double_mode, comm_ptr->GetMpiComm());
-      Assert(result.max - result.min < 1e-5,
+      Assert(result.max == result.min,
              ExcMessage(
                "Not all processors agree whether the last operation on "
                "this vector was an addition or a set operation. This will "