From c29e5849d8e0b22cbfb840459c9976b3877a24ea Mon Sep 17 00:00:00 2001
From: Martin Kronbichler <kronbichler@lnm.mw.tum.de>
Date: Sun, 5 Nov 2017 18:33:40 +0100
Subject: [PATCH] Filter away small numbers to avoid roundoff errors for
 floats.

---
 tests/full_matrix/full_matrix_09.cc | 5 +++--
 tests/full_matrix/full_matrix_10.cc | 2 +-
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/tests/full_matrix/full_matrix_09.cc b/tests/full_matrix/full_matrix_09.cc
index eff8fb1b12..77ececa4f1 100644
--- a/tests/full_matrix/full_matrix_09.cc
+++ b/tests/full_matrix/full_matrix_09.cc
@@ -41,7 +41,8 @@ void test()
 
   C.add(-1., E);
 
-  deallog << "Difference 1: " << (double)C.l1_norm() << std::endl;
+  const double tolerance = 100*std::numeric_limits<Number>::epsilon();
+  deallog << "Difference 1: " << filter_out_small_numbers(C.l1_norm(),tolerance) << std::endl;
 
   C = 0;
   for (unsigned int i=0; i<A.m(); ++i)
@@ -50,7 +51,7 @@ void test()
         C(i,j) += A(i,k) * B(k,j);
   C.add(-1., E);
 
-  deallog << "Difference 2: " << (double)C.l1_norm() << std::endl;
+  deallog << "Difference 2: " << filter_out_small_numbers(C.l1_norm(),tolerance) << std::endl;
 }
 
 int main()
diff --git a/tests/full_matrix/full_matrix_10.cc b/tests/full_matrix/full_matrix_10.cc
index a737ba7687..8860f2a3f3 100644
--- a/tests/full_matrix/full_matrix_10.cc
+++ b/tests/full_matrix/full_matrix_10.cc
@@ -41,7 +41,7 @@ void test()
         D(i,j) += A(i,k) * B(j,k);
   C.add(-1., D);
 
-  deallog << "Difference: " << (double)C.l1_norm() << std::endl;
+  deallog << "Difference: " << filter_out_small_numbers(C.l1_norm(), std::numeric_limits<Number>::epsilon()*50.) << std::endl;
 }
 
 int main()
-- 
2.39.5