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(fftw.info)FFTW Constants in Fortran

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FFTW Constants in Fortran
=========================

   When creating plans in FFTW, a number of constants are used to
specify options, such as `FFTW_FORWARD' or `FFTW_USE_WISDOM'.  The same
constants must be used with the wrapper routines, but of course the C
header files where the constants are defined can't be incorporated
directly into Fortran code.

   Instead, we have placed Fortran equivalents of the FFTW constant
definitions in the file `fortran/fftw_f77.i' of the FFTW package.  If
your Fortran compiler supports a preprocessor, you can use that to
incorporate this file into your code whenever you need to call FFTW.
Otherwise, you will have to paste the constant definitions in directly.
They are:

           integer FFTW_FORWARD,FFTW_BACKWARD
           parameter (FFTW_FORWARD=-1,FFTW_BACKWARD=1)
     
           integer FFTW_REAL_TO_COMPLEX,FFTW_COMPLEX_TO_REAL
           parameter (FFTW_REAL_TO_COMPLEX=-1,FFTW_COMPLEX_TO_REAL=1)
     
           integer FFTW_ESTIMATE,FFTW_MEASURE
           parameter (FFTW_ESTIMATE=0,FFTW_MEASURE=1)
     
           integer FFTW_OUT_OF_PLACE,FFTW_IN_PLACE,FFTW_USE_WISDOM
           parameter (FFTW_OUT_OF_PLACE=0)
           parameter (FFTW_IN_PLACE=8,FFTW_USE_WISDOM=16)
     
           integer FFTW_THREADSAFE
           parameter (FFTW_THREADSAFE=128)

   In C, you combine different flags (like `FFTW_USE_WISDOM' and
`FFTW_MEASURE') using the ``|'' operator; in Fortran you should just
use ``+''.