https://github.com/stephenberry/efftw

Modern C++ FFTW Wrapper for Eigen library
https://github.com/stephenberry/efftw

cpp eigen eigen3 fftw fftw3 fftw3-binding header-only

Last synced: about 1 month ago
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Modern C++ FFTW Wrapper for Eigen library

• Host: GitHub
• URL: https://github.com/stephenberry/efftw
• Owner: stephenberry
• License: mit
• Created: 2023-08-29T20:18:50.000Z (over 1 year ago)
• Default Branch: main
• Last Pushed: 2024-10-15T20:39:36.000Z (2 months ago)
• Last Synced: 2024-10-17T07:15:48.369Z (2 months ago)
• Topics: cpp, eigen, eigen3, fftw, fftw3, fftw3-binding, header-only
• Language: C++
• Homepage:
• Size: 34.2 KB
• Stars: 5
• Watchers: 3
• Forks: 3
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# Eigen-FFTW

> This repository is brand new and under heavy development!

E-FFTW is a modern C++20 wrapper library around [FFTW](http://www.fftw.org) for [Eigen](https://eigen.tuxfamily.org/index.php?title=Main_Page).

- Supports 1D and 2D FFTs

- Single header file: `#include "efftw/efftw.hpp"`

## Including

```cmake

include(FetchContent)

FetchContent_Declare(

  efftw

  GIT_REPOSITORY https://github.com/stephenberry/efftw

  GIT_TAG main

  GIT_SHALLOW TRUE

)

FetchContent_MakeAvailable(efftw)

target_link_libraries(${PROJECT_NAME} PRIVATE efftw::efftw)

```

>  Note: FFTW and Eigen dependencies are not included or installed by linking to `efftw::efftw`

## Example

```c++

#include "efftw/efftw.hpp"

int main()

{

   // init_threads must be called before the library is used

   efftw::init_threads(4); // set FFTW to use 4 threads

   // build a complex matrix

   Eigen::MatrixXcd mat(N, N);

   std::mt19937_64 g{}; // random number generator

   std::uniform_real_distribution dist{0.0, 1.0};

   for (size_t r = 0; r < N; ++r) {

      for (size_t c = 0; c < N; ++c) {

         mat(r, c) = { dist(g), dist(g) };

      }

   }

   

   efftw::f2 fft{mat}; // FFTW planning on construction (may be reused)

   fft(); // compute the FFT of mat in place

}

```

## API

```c++

using namespace efftw;

// classes

f1{vec} // 1D forward FFT (not normalized)

f2{mat} // 2D forward FFT

i1{vec} // 1D inverse FFT (1/(rows) normalization)

i2{mat} // 2D inverse FFT (1/(rows * cols) normalization)

// functions

shift1(vec) // 1D forward FFT shift

shift2(mat) // 2D forward FFT shift

inv_shift1(vec) // 1D inverse FFT shift

inv_shift2(mat) // 2D inverse FFT shift

```

## Important!

E-FFTW classes take references to Eigen types. Do not delete the matrix or resize it without rebuilding the EFFTW class.

The E-FFTW classes maintain the FFTW plan, which is deleted in the E-FFTW class destructors. The classes are used to keep the plan alive and allow the same matrix memory to be used multiple times. It is inefficient to rebuild the plan, but the plan needs to be rebuilt if the size of the matrix or vector changes.

## Alias Type Deduction

```c++

// For clang, alias type deduction is not yet supported, so you will need to write:

efftw::f2 fft{mat};

```