anchor.diff:  ln -s path/to/vcl
   ----
   
  -____
  +[TIP]
   If you do not like this, you can also set the include paths in your own config file as
   described link:config/README.md[here].
  -____
   
   Now let us compile the first benchmark program.
   
  
positive.code: #or
  make blas_b device=gpu #(if you have a gpu and nvcc )
  ----
  
  
  Run the code with
  
  
negative.code: which makes a grid with 3 polynomial coefficients, 100 cells in x, 100
  cells in y and 10 in z. If you compiled for OpenMP, you can set the
  number of threads with e.g. `export OMP_NUM_THREADS=4`.
  [TIP]
  This is a
  benchmark program to benchmark various elemental functions the library
  is built on. Go ahead and vary the input parameters and see how your
  hardware performs. You can compile and run any other program that ends
  in `_t.cu` (test programs) or `_b.cu` (benchmark programs) in
  `feltor/inc/dg` in this way.
  
  Now, let us test the mpi setup
  [TIP]
  You can of course skip this if you
  don't have mpi installed on your computer. If you intend to use the
  MPI backend, an implementation library of the mpi standard is required.
  Per default `mpic++` is used for compilation.
  
  [source,sh]
  ----
  