Merge branch 'umfpacksolver-with-scalar-matrix-entries' into 'master'

Implement addToDiagonal for scalars (interpreted as 1x1 matrices)

See merge request agnumpde/dune-matrix-vector!12

.gitlab-ci.yml

@@ -9,6 +9,6 @@ dune:git  gcc-8  C++17:
   image: registry.dune-project.org/docker/ci/dune:git-debian-10-gcc-8-17
   script: duneci-standard-test
 
-dune:git  gcc-6  C++14:
-  image: registry.dune-project.org/docker/ci/dune:git-debian-9-gcc-6-14
+dune:git  gcc-9  C++20:
+  image: registry.dune-project.org/docker/ci/dune:git-debian-11-gcc-9-20
   script: duneci-standard-test

CHANGELOG.md

 # Master (will become release 2.8)
 
-- ...
+- The method `addToDiagonal` can now also be called if the matrix is a scalar number type.
+  This is needed since nowadays scalar entries can end the nesting recursion of dune-istl
+  matrices.
 
 ## Deprecations and removals
 

dune/matrix-vector/addtodiagonal.hh

@@ -11,6 +11,14 @@ namespace MatrixVector {
       x[i][i] += a;
   }
 
+  /** \brief Specialization for scalars (to be interpreted as 1x1 matrices) */
+  template <class Matrix>
+  static void addToDiagonal(Matrix& x, const Matrix& a)
+  {
+    static_assert(IsNumber<Matrix>::value, "Only scalars can be treated both as matrix and as number!");
+    x += a;
+  }
+
   /*
     the line
 

dune/matrix-vector/test/resizetest.cc

@@ -77,7 +77,7 @@ bool checkResize() {
     FV fv;
     resize(fv, Dune::FieldVector<int, 5>());
     return false;
-  } catch (Dune::Exception) {
+  } catch (Dune::Exception&) {
     // TODO make sure the right exception is thrown
   }
 
@@ -116,9 +116,9 @@ bool checkResize() {
     // test "unnatural" matrix types
     // TODO
 
-  } catch (Dune::Exception e) {
+  } catch (Dune::Exception& e) {
     std::cout << "FAILURE." << std::endl;
-    std::cout << e << std::endl;
+    std::cout << e.what() << std::endl;
     return false;
   }
 

dune/matrix-vector/test/staticmatrixtoolstest.cc

@@ -35,6 +35,16 @@ private:
 
     // SQUARE MATRICES
 
+    // scalars
+    {
+      FieldType scalarMatrix_x = 1,
+                scalarMatrix_check = 4;
+
+      addToDiagonal(scalarMatrix_x, scalar_a);
+
+      passed = passed and
+               myDiff(scalarMatrix_x, scalarMatrix_check) < 1e-12;
+    }
     // case FM
     {
       Dune::FieldMatrix<FieldType, 2, 2> squareFieldMatrix_x = {{1, 2}, {3, 4}},

dune/matrix-vector/triangularsolve.hh

@@ -37,7 +37,7 @@ namespace MatrixVector {
           // Note: We could drop the check for ignore nodes here bcs. b[j] will
           // be ignored anyway due to the check above.
           if (ignore == nullptr or (*ignore)[j].none())
-            b[j] -= x[i] * *cIt;
+            cIt->mmv(x[i], b[j]);
         }
       }
     } else {