Building the spectral solver

By default, the code is compiled with a finite-difference (FDTD) Maxwell solver. In order to run the code with a spectral solver, you need to:

• Install (or load) an MPI-enabled version of FFTW. For instance, for Debian, this can be done with

  apt-get install libfftw3-dev libfftw3-mpi-dev
  

• Set the environment variable FFTW_HOME to the path for FFTW. For instance, for Debian, this is done with

  export FFTW_HOME=/usr/
  

• Set USE_FFT=TRUE when compiling:

  make -j 4 USE_FFT=TRUE
  

See Building WarpX to use RZ geometry for using the spectral solver with USE_RZ. Additional steps are needed. PSATD is compatible with single precision, but please note that, on CPU, FFTW needs to be compiled with option --enable-float.