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.

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.