Calculate plot:

./calc

Plot it:

./run

To generate VTK from Python or Fortran, use the legacy ASCII VTK format. It is easy to write and can be manually checked. Then use it as it is in ParaView, or convert it to the newest XML binary format using:

./vtk2xml.py xx.vtk

This will generate xx.vtr (the extension will depend on the type of data in xx.vtk).