#### 6.12.1 MPI Files and Data Types ¶

All programs using FFTW’s MPI support should include its header file:

    #include <fftw3-mpi.h>

Note that this header file includes the serial-FFTW `fftw3.h` header file, and also the `mpi.h` header file for MPI, so you need not include those files separately.

You must also link to both the FFTW MPI library and to the serial FFTW library. On Unix, this means adding `-lfftw3_mpi -lfftw3 -lm` at the end of the link command.

Different precisions are handled as in the serial interface: See Precision. That is, ‘`fftw_`’ functions become `fftwf_` (in single precision) etcetera, and the libraries become `-lfftw3f_mpi -lfftw3f -lm` etcetera on Unix. Long-double precision is supported in MPI, but quad precision (‘`fftwq_`’) is not due to the lack of MPI support for this type.