Implement the 'printmatrix' method for scalar matrix entries

Simplify the implementation while we're there.  The IsNumber trait
allows much simpler recursion termination.

dune/istl/io.hh

@@ -151,6 +151,31 @@ namespace Dune {
     }
   }
 
+  /**
+   * \brief Print one row of a matrix, specialization for number types
+   *
+   * \code
+   * #include <dune/istl/io.hh>
+   * \endcode
+   */
+  template<class K>
+  void print_row (std::ostream& s, const K& value,
+                  typename FieldMatrix<K,1,1>::size_type I,
+                  typename FieldMatrix<K,1,1>::size_type J,
+                  typename FieldMatrix<K,1,1>::size_type therow,
+                  int width, int precision,
+                  typename std::enable_if_t<Dune::IsNumber<K>::value>* sfinae = nullptr)
+  {
+    DUNE_UNUSED_PARAMETER(I);
+    DUNE_UNUSED_PARAMETER(J);
+    DUNE_UNUSED_PARAMETER(therow);
+    DUNE_UNUSED_PARAMETER(precision);
+
+    s << " ";         // space in front of each entry
+    s.width(width);   // set width for each entry anew
+    s << value;
+  }
+
   /**
    * \brief Print one row of a matrix
    *
@@ -161,7 +186,8 @@ namespace Dune {
   template<class M>
   void print_row (std::ostream& s, const M& A, typename M::size_type I,
                   typename M::size_type J, typename M::size_type therow,
-                  int width, int precision)
+                  int width, int precision,
+                  typename std::enable_if_t<!Dune::IsNumber<M>::value>* sfinae = nullptr)
   {
     typename M::size_type i0=I;
     for (typename M::size_type i=0; i<A.N(); i++)
@@ -190,60 +216,6 @@ namespace Dune {
     }
   }
 
-  /**
-   * \brief Print one row of a matrix, specialization for FieldMatrix
-   *
-   * \code
-   * #include <dune/istl/io.hh>
-   * \endcode
-   */
-  template<class K, int n, int m>
-  void print_row (std::ostream& s, const FieldMatrix<K,n,m>& A,
-                  typename FieldMatrix<K,n,m>::size_type I,
-                  typename FieldMatrix<K,n,m>::size_type J,
-                  typename FieldMatrix<K,n,m>::size_type therow, int width,
-                  int precision)
-  {
-    DUNE_UNUSED_PARAMETER(J);
-    DUNE_UNUSED_PARAMETER(precision);
-
-    typedef typename FieldMatrix<K,n,m>::size_type size_type;
-
-    for (size_type i=0; i<n; i++)
-      if (I+i==therow)
-        for (int j=0; j<m; j++)
-        {
-          s << " ";         // space in front of each entry
-          s.width(width);   // set width for each entry anew
-          s << A[i][j];     // yeah, the number !
-        }
-  }
-
-  /**
-   * \brief Print one row of a matrix, specialization for FieldMatrix<K,1,1>
-   *
-   * \code
-   * #include <dune/istl/io.hh>
-   * \endcode
-   */
-  template<class K>
-  void print_row (std::ostream& s, const FieldMatrix<K,1,1>& A,
-                  typename FieldMatrix<K,1,1>::size_type I,
-                  typename FieldMatrix<K,1,1>::size_type J,
-                  typename FieldMatrix<K,1,1>::size_type therow,
-                  int width, int precision)
-  {
-    DUNE_UNUSED_PARAMETER(J);
-    DUNE_UNUSED_PARAMETER(precision);
-
-    if (I==therow)
-    {
-      s << " ";         // space in front of each entry
-      s.width(width);   // set width for each entry anew
-      s << static_cast<K>(A);         // yeah, the number !
-    }
-  }
-
   /**
    * \brief Print a generic block matrix
    *

dune/istl/test/iotest.cc

@@ -83,4 +83,21 @@ int main(int argc, char** argv)
   v3.push_back(1);
   v3.push_back(2);
   Dune::writeVectorToMatlabHelper(v3, std::cout);
+
+  // Test the printmatrix method
+  {
+    Dune::BCRSMatrix<double> matrix;
+    setupLaplacian(matrix, 3);
+    Dune::printmatrix(std::cout, matrix, "matrix", "--");
+  }
+  {
+    Dune::BCRSMatrix<Dune::FieldMatrix<double,1,1> > matrix;
+    setupLaplacian(matrix, 3);
+    Dune::printmatrix(std::cout, matrix, "matrix", "--");
+  }
+  {
+    Dune::BCRSMatrix<Dune::FieldMatrix<double,2,3> > matrix;
+    setupLaplacian(matrix, 3);
+    Dune::printmatrix(std::cout, matrix, "matrix", "--");
+  }
 }