Visualization

Data written in the GraPE format using the Dune::DataWriter class can be either directly visualized during the computation or can be read separately with the datadisp utility file. More detail on how to write data to files can be found in DiscFuncIO.

If data is to be visualized during a computation the Dune::DataWriter can also be used by setting the parameter fem.io.grapedisplay to 1. Each time a file is written to disk, the data is simultaneously displayed in GraPE. By pressing the exit button in GraPE the computation is resumed.

For reading data from disk into GraPE the programm fem/io/visual/grape/datadisp/datadisp.cc can be used. An example of its usage can be found in the file fem/io/visual/grape/datadisp/programtemplate.cc

In the simplest case the following program can be used:

typedef IOTupleType GR_InputType;
template <class GrapeDispType,
          class GR_GridType,
          class DestinationType>
void postProcessing(const GrapeDispType& disp,
                    const GR_GridType& grid,
                    const double time,
                    const DestinationType& Uh)
{}
#include <dune/fem/io/visual/grape/datadisp/datadisp.cc>

In the file included in the last line the function main() is defined. The resulting executable expects the start and end index of the data files which are to be read. The file prefix and the directory are prescribed through runtime parameters with the same keys used in the Dune::DataWriter described in DiscFuncIO.

The type GR_InputType should be a tuple type holding the types of the discrete functions to be read. The postProcessing method is called after each data set is read. The corresponding discrete functions are passed in the third parameter; the first parameter holds the grape handle. Further data, e.g., errors and derived values, can be added to the display by using the method disp.addData(...) as described in the class Dune::GrapeDataDisplay. An example which adds the difference between a discrete solution and an analytical solution can be found in fem/io/visual/grape/datadisp/errordisplay.hh.