Add test for invert 4x4 matrix specialization

CMakeLists_files.cmake

@@ -94,6 +94,7 @@ list (APPEND TEST_SOURCE_FILES
   # tests/test_thresholdpressure.cpp
   tests/test_wellswitchlogger.cpp
   tests/test_timer.cpp
+  tests/test_invert.cpp
   )
 
 list (APPEND TEST_DATA_FILES

opm/autodiff/ISTLSolver.hpp

@@ -169,8 +169,8 @@ static inline K invertMatrix (const FieldMatrix<K,4,4> &matrix, FieldMatrix<K,4,
         }
         return 1.0;
     }
-    det = 1.0 / det;
+    K inv_det = 1.0 / det;
-    inverse *= det;
+    inverse *= inv_det;
 
     return det;
 }

tests/test_invert.cpp

@@ -0,0 +1,77 @@
+/*
+  Copyright 2017 IRIS AS
+
+  This file is part of the Open Porous Media Project (OPM).
+
+  OPM is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  OPM is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with OPM.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <config.h>
+
+#if HAVE_DYNAMIC_BOOST_TEST
+#define BOOST_TEST_DYN_LINK
+#endif
+
+#define BOOST_TEST_MODULE InvertSpecializationTest
+#include <boost/test/unit_test.hpp>
+#include <opm/autodiff/ISTLSolver.hpp>
+
+void checkIdentity(Dune::FieldMatrix<double, 4, 4> M) {
+    double diag = 0.0;
+    double offDiag = 0.0;
+    for (int i = 0; i < 4; ++i) {
+        for (int j = 0; j < 4; ++j) {
+            if (i == j)
+                diag += M[i][j];
+            else
+                offDiag += M[i][j];
+        }
+    }
+    BOOST_CHECK_CLOSE(4, diag, 1e-14);
+    BOOST_CHECK_SMALL(offDiag, 1e-14);
+}
+
+BOOST_AUTO_TEST_CASE(Invert4x4)
+{
+    typedef Dune::FieldMatrix<double, 4, 4>  BaseType;
+    BaseType matrix;
+    BaseType eye;
+    BaseType inverse;
+
+    for (int i = 0; i < 4; ++i) {
+        for (int j = 0; j < 4; ++j) {
+                matrix[i][j] = i + 4*j + 1;
+        }
+    }
+    BaseType matrix_sing (matrix);
+    // make matrix non-singular
+    matrix[3][0] = 5;
+    matrix[0][3] = 14;
+
+    double det = Dune::FMatrixHelp::invertMatrix(matrix, inverse);
+    BOOST_CHECK_CLOSE(4, det, 1e-14);
+
+    // check matrix * inverse close to identiy
+    checkIdentity(matrix.rightmultiply(inverse));
+
+    // check return identity matrix if singular matrix
+    inverse = 0.0;
+    double det2 = Dune::FMatrixHelp::invertMatrix(matrix_sing, inverse);
+    BOOST_CHECK_CLOSE(1.0, det2, 1e-14);
+    checkIdentity(inverse);
+}
+
+
+
+