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Chris@82:When creating plans in FFTW, a number of constants are used to specify
Chris@82: options, such as FFTW_MEASURE or FFTW_ESTIMATE. The
Chris@82: same constants must be used with the wrapper routines, but of course the
Chris@82: C header files where the constants are defined can’t be incorporated
Chris@82: directly into Fortran code.
Chris@82:
Instead, we have placed Fortran equivalents of the FFTW constant
Chris@82: definitions in the file fftw3.f, which can be found in the same
Chris@82: directory as fftw3.h. If your Fortran compiler supports a
Chris@82: preprocessor of some sort, you should be able to include or
Chris@82: #include this file; otherwise, you can paste it directly into
Chris@82: your code.
Chris@82:
In C, you combine different flags (like FFTW_PRESERVE_INPUT and
Chris@82: FFTW_MEASURE) using the ‘|’ operator; in Fortran
Chris@82: you should just use ‘+’. (Take care not to add in the
Chris@82: same flag more than once, though. Alternatively, you can use the
Chris@82: ior intrinsic function standardized in Fortran 95.)
Chris@82: