From 207ba9c7e76d2f3f4b35261417207f91800ea239 Mon Sep 17 00:00:00 2001
From: Jean-Paul Pelteret <jppelteret@gmail.com>
Date: Wed, 24 Oct 2018 14:08:51 +0200
Subject: [PATCH] Add an assertion

---
 source/base/incremental_function.cc | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/source/base/incremental_function.cc b/source/base/incremental_function.cc
index d65d479e9e..027424e6d9 100644
--- a/source/base/incremental_function.cc
+++ b/source/base/incremental_function.cc
@@ -36,6 +36,8 @@ namespace Functions
   IncrementalFunction<dim, RangeNumberType>::set_decrement(
     const time_type delta)
   {
+    Assert(delta >= 0.0,
+           ExcMessage("The decrement must be set to a non-negative value."));
     delta_t = delta;
   }
 
-- 
2.39.5