From: Wolfgang Bangerth Date: Sun, 4 Mar 2018 08:23:50 +0000 (-0700) Subject: Update a couple of things on how we generate output in the example steps. X-Git-Tag: v9.0.0-rc1~341^2 X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=refs%2Fpull%2F5998%2Fhead;p=dealii.git Update a couple of things on how we generate output in the example steps. --- diff --git a/examples/step-6/step-6.cc b/examples/step-6/step-6.cc index eeb1a7ec67..b81c0dd84a 100644 --- a/examples/step-6/step-6.cc +++ b/examples/step-6/step-6.cc @@ -562,22 +562,33 @@ void Step6::refine_grid () // next cycle with mesh refinement, we want to output the results from this // cycle. // -// In the present program, we will not write the solution (except for in the -// last step, see the next function), but only the meshes that we generated, -// as a two-dimensional Encapsulated Postscript (EPS) file. +// We have already seen in step-1 how this can be achieved for the +// mesh itself. The only thing we have to change is the generation of +// the file name, since it should contain the number of the present +// refinement cycle provided to this function as an argument. To this +// end, we simply append the number of the refinement cycle as a +// string to the file name. // -// We have already seen in step-1 how this can be achieved. The only thing we -// have to change is the generation of the file name, since it should contain -// the number of the present refinement cycle provided to this function as an -// argument. To this end, we simply append the number of the refinement cycle -// as a string to the file name. +// We also output the solution in the same way as we did before, with +// a similarly constructed file name. template void Step6::output_results (const unsigned int cycle) const { - std::ofstream output ("grid-" + std::to_string(cycle) + ".eps"); - - GridOut grid_out; - grid_out.write_eps (triangulation, output); + { + GridOut grid_out; + std::ofstream output ("grid-" + std::to_string(cycle) + ".eps"); + grid_out.write_eps (triangulation, output); + } + + { + DataOut data_out; + data_out.attach_dof_handler (dof_handler); + data_out.add_data_vector (solution, "solution"); + data_out.build_patches (); + + std::ofstream output ("solution-" + std::to_string(cycle) + ".vtk"); + data_out.write_vtk (output); + } } @@ -641,24 +652,6 @@ void Step6::run () solve (); output_results (cycle); } - - // After we have finished computing the solution on the finest mesh, and - // writing all the grids to disk, we want to also write the actual solution - // on this final mesh to a file. As already done in one of the previous - // examples, we use the EPS format for output, and to obtain a reasonable - // view on the solution, we rescale the z-axis by a factor of four. - DataOutBase::EpsFlags eps_flags; - eps_flags.z_scaling = 4; - - DataOut data_out; - data_out.set_flags (eps_flags); - - data_out.attach_dof_handler (dof_handler); - data_out.add_data_vector (solution, "solution"); - data_out.build_patches (); - - std::ofstream output ("final-solution.eps"); - data_out.write_eps (output); } diff --git a/examples/step-8/doc/results.dox b/examples/step-8/doc/results.dox index d9e0ab361c..5d0d4271c7 100644 --- a/examples/step-8/doc/results.dox +++ b/examples/step-8/doc/results.dox @@ -4,7 +4,7 @@ There is not much to be said about the results of this program, other than that they look nice. All images were made using Visit from the output files that the program wrote to disk. The first two pictures show -the $x$- and $y$-displacements as a scalar components: +the $x$- and $y$-displacements as scalar components: @@ -38,7 +38,7 @@ scalars, and Visit then faithfully assumes that this is indeed what it is. In other words, once we have written the data as scalars, there is nothing in Visit that allows us to paste these two scalar fields back together as a vector field. Where we would have to attack this problem is at the root, -namely in ElasticProblem::output_results. We won't do so here but +namely in ElasticProblem::output_results(). We won't do so here but instead refer the reader to the step-22 program where we show how to do this for a more general situation. That said, we couldn't help generating the data anyway that would show how this would look if implemented as discussed in diff --git a/examples/step-8/step-8.cc b/examples/step-8/step-8.cc index 1ed56e2a46..af6fe3d4e2 100644 --- a/examples/step-8/step-8.cc +++ b/examples/step-8/step-8.cc @@ -514,41 +514,32 @@ namespace Step8 // valued. The DataOut class takes care of this automatically, // but we have to give each component of the solution vector a different // name. + // + // To do this, the DataOut::add_vector() function wants a vector of + // strings. Since the number of components is the same as the number + // of dimensions we are working in, we use the switch + // statement below. + // + // We note that some graphics programs have restriction on what + // characters are allowed in the names of variables. deal.II therefore + // supports only the minimal subset of these characters that is supported + // by all programs. Basically, these are letters, numbers, underscores, + // and some other characters, but in particular no whitespace and + // minus/hyphen. The library will throw an exception otherwise, at least + // if in debug mode. + // + // After listing the 1d, 2d, and 3d case, it is good style to let the + // program die if we run upon a case which we did not consider. Remember + // that the Assert macro generates an exception if the + // condition in the first parameter is not satisfied. Of course, the + // condition false can never be satisfied, so the program + // will always abort whenever it gets to the default statement: template void ElasticProblem::output_results (const unsigned int cycle) const { - std::string filename = "solution-"; - filename += ('0' + cycle); - Assert (cycle < 10, ExcInternalError()); - - filename += ".vtk"; - std::ofstream output (filename.c_str()); - DataOut data_out; data_out.attach_dof_handler (dof_handler); - - - // As said above, we need a different name for each component of the - // solution function. To pass one name for each component, a vector of - // strings is used. Since the number of components is the same as the - // number of dimensions we are working in, the following - // switch statement is used. - // - // We note that some graphics programs have restriction as to what - // characters are allowed in the names of variables. The library therefore - // supports only the minimal subset of these characters that is supported - // by all programs. Basically, these are letters, numbers, underscores, - // and some other characters, but in particular no whitespace and - // minus/hyphen. The library will throw an exception otherwise, at least - // if in debug mode. - // - // After listing the 1d, 2d, and 3d case, it is good style to let the - // program die if we run upon a case which we did not consider. Remember - // that the Assert macro generates an exception if the - // condition in the first parameter is not satisfied. Of course, the - // condition false can never be satisfied, so the program - // will always abort whenever it gets to the default statement: std::vector solution_names; switch (dim) { @@ -568,16 +559,18 @@ namespace Step8 Assert (false, ExcNotImplemented()); } - // After setting up the names for the different components of the solution - // vector, we can add the solution vector to the list of data vectors - // scheduled for output. Note that the following function takes a vector - // of strings as second argument, whereas the one which we have used in - // all previous examples accepted a string there. In fact, the latter - // function is only a shortcut for the function which we call here: it - // puts the single string that is passed to it into a vector of strings - // with only one element and forwards that to the other function. + // After setting up the names for the different components of the + // solution vector, we can add the solution vector to the list of + // data vectors scheduled for output. Note that the following + // function takes a vector of strings as second argument, whereas + // the one which we have used in all previous examples accepted a + // string there. (In fact, the function we had used before would + // convert the single string into a vector with only one element + // and forwards that to the other function.) data_out.add_data_vector (solution, solution_names); data_out.build_patches (); + + std::ofstream output ("solution-" + std::to_string(cycle) + ".vtk"); data_out.write_vtk (output); } diff --git a/examples/step-9/doc/results.dox b/examples/step-9/doc/results.dox index 8b7f9c4719..3dd4b6fea4 100644 --- a/examples/step-9/doc/results.dox +++ b/examples/step-9/doc/results.dox @@ -3,7 +3,7 @@ The results of this program are not particularly spectacular. They consist of the console output, some grid files, and the solution on -the finest grid. First for the console output: +each of these grids. First for the console output: @code Cycle 0: Number of active cells: 256 @@ -34,13 +34,14 @@ displayed in the following picture: The structure of the grid will be understandable by looking at the -solution itself: +final solution itself: - - +(This image was generated using an earlier version of the program that +still generated gmv instead of VTK output, and so is visualized +using gmv.) Note that the solution is created by that part that is transported along the wiggly advection field from the left and lower boundaries to the top right, and the part that is created by the source in the diff --git a/examples/step-9/step-9.cc b/examples/step-9/step-9.cc index 2878ba8ae5..0c51bd9893 100644 --- a/examples/step-9/step-9.cc +++ b/examples/step-9/step-9.cc @@ -903,19 +903,25 @@ namespace Step9 // Writing output to disk is done in the same way as in the previous - // examples... + // examples. Indeed, the function is identical to the one in step-6. template void AdvectionProblem::output_results (const unsigned int cycle) const { - std::string filename = "grid-"; - filename += ('0' + cycle); - Assert (cycle < 10, ExcInternalError()); + { + GridOut grid_out; + std::ofstream output ("grid-" + std::to_string(cycle) + ".eps"); + grid_out.write_eps (triangulation, output); + } - filename += ".eps"; - std::ofstream output (filename.c_str()); + { + DataOut data_out; + data_out.attach_dof_handler (dof_handler); + data_out.add_data_vector (solution, "solution"); + data_out.build_patches (); - GridOut grid_out; - grid_out.write_eps (triangulation, output); + std::ofstream output ("solution-" + std::to_string(cycle) + ".vtk"); + data_out.write_vtk (output); + } } @@ -952,14 +958,6 @@ namespace Step9 solve (); output_results (cycle); } - - DataOut data_out; - data_out.attach_dof_handler (dof_handler); - data_out.add_data_vector (solution, "solution"); - data_out.build_patches (); - - std::ofstream output ("final-solution.vtk"); - data_out.write_vtk (output); }