anchor.diff:  chooses the correct implementation for you! This is a first example of a
   __container free numerical algorithm__.
   
  -=== Using FELTOR on Windows
  -FELTOR has been developed mostly on Linux machines. Recently, it has
  -become possible to develop on Windows using https://www.visualstudio.com/[Microsoft Visual Studio].
  -____
  -Unfortunately, the msvc compiler only supports an outdated OpenMP version so
  -consider a performance penalty of approximately factor 2, when running the OpenMP backend on Windows.
  -____
  -
  -For the download of the library and its dependencies described <<sec_quickstart,previously>> you may want
  -to activate Bash in Windows 10 or
  - consider a software solution like https://desktop.github.com
  -____
  -The include paths need to be set in the project properties.
  -Please also enable the use of intrinsic functions, the AVX2 instruction set and
  -activate OpenMP support.
  -It is important to set the Platform to x64!
  -____
  -
   === Running a FELTOR simulation
   
   Now, we want to compile and run a simulation program. To this end, we have to
  
positive.code: | *GPU*     | - | NVidia GPU with compute-capability > 6 and nvcc-8.0
  | *MPI*     | - | mpi installation compatible with compiler (must be cuda-aware in case hybrid MPI+GPU is the target system)
  |=======================================================================
  ____
  Our GPU backend uses the
  https://developer.nvidia.com/cuda-zone[Nvidia-CUDA] programming
  environment and in order to compile and run a program for a GPU a user
  
negative.code: compiler. The CPU version of the backend is equally valid and provides
  the same functionality. Analogously, an MPI installation is only required if the user targets
  a distributed memory system.
  
  === Running a FELTOR test or benchmark program
  
  