Minor changes.

git-svn-id: https://svn.dealii.org/trunk@16085 0785d39b-7218-0410-832d-ea1e28bc413d

diff --git a/deal.II/examples/step-33/step-33.cc b/deal.II/examples/step-33/step-33.cc
index 02a1d389351c73cb04ebcd70e46964bcfeb24ca7..75167f12b911493b49af17b3d1e313a3932fdb11 100644 (file)
--- a/deal.II/examples/step-33/step-33.cc
+++ b/deal.II/examples/step-33/step-33.cc
@@ -164,7 +164,21 @@ struct EulerEquations
                                     // conservation law for the
                                     // component in that row.  The
                                     // exact form of this matrix is
-                                    // given in the introduction.
+                                    // given in the
+                                    // introduction. Note that we
+                                    // know the size of the matrix:
+                                    // it has as many rows as the
+                                    // system has components, and
+                                    // <code>dim</code> columns;
+                                    // rather than using a FullMatrix
+                                    // object for such a matrix
+                                    // (which has a variable number
+                                    // of rows and columns and must
+                                    // therefore allocate memory on
+                                    // the heap each time such a
+                                    // matrix is created), we use a
+                                    // rectangular array of numbers
+                                    // right away.
                                     //
                                     // We templatize the numerical
                                     // type of the flux function so
@@ -176,9 +190,7 @@ struct EulerEquations
                                     // \rho w_{d-1}, \rho, E$, so
                                     // they do not look exactly like
                                     // the Euler equations one is
-                                    // used to seeing.  We evaluate
-                                    // the flux at a single
-                                    // quadrature point.
+                                    // used to seeing.
     template <typename number>
     static
     void flux_matrix (const std::vector<number> &W,
@@ -221,12 +233,12 @@ struct EulerEquations
        
                                         // Then the terms for the
                                         // density (i.e. mass
-                                        // conservation):
+                                        // conservation), and,
+                                        // lastly, conservation of
+                                        // energy:
        for (unsigned int d=0; d<dim; ++d)
          flux[density_component][d] = W[first_momentum_component+d]; 
 
-                                        // And, lastly, conservation
-                                        // of energy:
        for (unsigned int d=0; d<dim; ++d)
          flux[energy_component][d] = W[first_momentum_component+d] /
                                      W[density_component] *
@@ -275,9 +287,13 @@ const double EulerEquations<dim>::gas_gamma = 1.4;
 
 
                                 // @sect3{Conservation Law class}
-                                // Here we define a Conservation Law class that helps group
-                                // operations and data for our Euler equations into a manageable
-                                // entity.  Functions will be described as their definitions appear.
+
+                                // Here we define a Conservation Law
+                                // class that helps group operations
+                                // and data for our Euler equations
+                                // into a manageable entity.  Member
+                                // functions will be described as
+                                // their definitions appear.
 template <int dim>
 class ConsLaw
 {