fftw3cxx

FFTW, the Fastest Fourier Transform in the West, is a widely used C library for computing the discrete Fourier transform (DFT) in multiple sizes and dimensions. The current major API version is 3.

fftw3cxx is a thin C++ interface wrapper to make FFTW3 a little more user friendly in C++. It's goals are to:

• provide a C++ plan template class for holding FFTW3 plans with:
  • the RAII idiom,
  • the named constructor idiom for plan creation methods, and
  • reference counting of created plans
• provide direct use of the C++ std::complex<> template types (in addition to the FFTW3 complex types)
• consist of only a thin wrapper around the existing FFTW3 API, with only small inline forwarding functions
• be wrapped in a single C++ namespace, fftw3cxx
• be implemented in a one-file header-only library, fftw3cxx.h, that can be cherry-picked into projects using FFTW3 (or not)

FFTW3 uses a "huge second-order macro" to implement templates in the C preprocessor, expanding this macro once for each supported type. fftw3cxx wraps and forwards the complete FFTW3 API with C++ template types, using a large macro in the style of fftw3.h. C++ template specialization is used to implement each of the FFTW3 types.

FFTW3 prefix	C type	fftw3cxx prefix
fftw_	double	fftw<double>::
fftwf_	float	fftw<float>::
fftwl_	long double	fftw<long double>::

This re-prefixed API isn't necessarily intended for direct use, but is a helpful step toward the desired fftw3cxx API: the plan class. With this re-prefixed API, the desired plan class is a straightforward template class with inline forwarder methods. All of the FFTW3 functions that want to be plan methods are included in class fftw3cxx::plan<T>:

• plan creation named constructors: plan_*, e.g. plan_dft_1d
• plan execution: execute_*, e.g. execute_dft
• plan utilities: print, flops, etc.

The remaining functions in the FFTW3 API are template functions directly in the fftw3cxx namespace, e.g. fftw3cxx::cleanup<T>(), fftw3cxx::import_wisdom_from_filename<T>(...), etc.

Because fftw3cxx is only a thin wrapper around the FFTW3 API, no documentation is provided or needed. Refer directly to the FFTW3 function with the same name.