From 980a2c0182d2df37f60a65d45105291477eb6d4b Mon Sep 17 00:00:00 2001
From: Roland Richter <Roland.Richter2@gmx.de>
Date: Tue, 15 Oct 2019 10:26:19 +0200
Subject: [PATCH] Safety check for usable eigenvalues extended to non-symmetric
 matrices

---
 include/deal.II/lac/arpack_solver.h | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/include/deal.II/lac/arpack_solver.h b/include/deal.II/lac/arpack_solver.h
index 4bbdb42c02..1ea8407214 100644
--- a/include/deal.II/lac/arpack_solver.h
+++ b/include/deal.II/lac/arpack_solver.h
@@ -483,6 +483,21 @@ inline ArpackSolver::AdditionalData::AdditionalData(
         ExcMessage(
           "'smallest imaginary part' can only be used for non-symmetric problems!"));
     }
+  // Check for possible options for asymmetric problems
+  else
+    {
+      Assert(
+        eigenvalue_of_interest != algebraically_largest,
+        ExcMessage(
+          "'largest algebraic part' can only be used for symmetric problems!"));
+      Assert(
+        eigenvalue_of_interest != algebraically_smallest,
+        ExcMessage(
+          "'smallest algebraic part' can only be used for symmetric problems!"));
+      Assert(eigenvalue_of_interest != both_ends,
+             ExcMessage(
+               "'both ends' can only be used for symmetric problems!"));
+    }
 }
 
 
-- 
2.39.5