fft.hpp File Reference

Fast Fourier Transform interface for spectral methods. More...

#include "core/decomposition.hpp"
#include "openpfc/backends/heffte_adapter.hpp"
#include "openpfc/core/backend_tags.hpp"
#include "openpfc/core/databuffer.hpp"
#include "openpfc/core/world.hpp"
#include "openpfc/fft/kspace.hpp"
#include <heffte.h>
#include <iostream>
#include <memory>
#include <mpi.h>

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Classes
struct	pfc::fft::layout::FFTLayout
	Structure to hold the layout of FFT data. More...
struct	pfc::fft::IFFT
struct	pfc::fft::FFT_Impl< BackendTag >
	FFT class for distributed-memory parallel Fourier transforms. More...

Typedefs
using	pfc::fft::layout::box3di = heffte::box3d< int >
using	pfc::fft::layout::Decomposition = pfc::decomposition::Decomposition
using	pfc::fft::Decomposition = pfc::decomposition::Decomposition
using	pfc::fft::RealVector = std::vector< double >
using	pfc::fft::ComplexVector = std::vector< std::complex< double > >
using	pfc::fft::box3di = heffte::box3d< int >
	Type alias for 3D integer box.
using	pfc::fft::RealDataBuffer = core::DataBuffer< backend::CpuTag, double >
using	pfc::fft::ComplexDataBuffer = core::DataBuffer< backend::CpuTag, std::complex< double > >
using	pfc::fft::fft_r2c = heffte::fft3d_r2c< heffte::backend::fftw >
	FFTW backend (CPU)
using	pfc::fft::FFT = FFT_Impl< heffte::backend::fftw >
using	pfc::FFT = fft::FFT
	Type alias for FFT class.
using	pfc::FFTLayout = fft::layout::FFTLayout
	Type alias for FFTLayout class.

Enumerations
enum class	pfc::fft::Backend { FFTW , CUDA }
	FFT backend selection. More...

Functions
const FFTLayout	pfc::fft::layout::create (const Decomposition &decomposition, int r2c_direction)
	Creates an FFTLayout object based on the given decomposition and parameters.
const auto &	pfc::fft::layout::get_real_box (const FFTLayout &layout, int i)
const auto &	pfc::fft::layout::get_complex_box (const FFTLayout &layout, int i)
auto	pfc::fft::layout::get_r2c_direction (const FFTLayout &layout)
template<typename BackendTag >
const auto &	pfc::fft::get_fft_object (const FFT_Impl< BackendTag > &fft) noexcept
template<typename BackendTag >
auto	pfc::fft::get_inbox (const FFT_Impl< BackendTag > &fft) noexcept
template<typename BackendTag >
auto	pfc::fft::get_outbox (const FFT_Impl< BackendTag > &fft) noexcept
FFT	pfc::fft::create (const FFTLayout &fft_layout, int rank_id, plan_options options)
	Creates an FFT object based on the given FFTLayout and rank ID.
FFT	pfc::fft::create (const Decomposition &decomposition, int rank_id)
	Creates an FFT object based on the given decomposition and rank ID.
FFT	pfc::fft::create (const Decomposition &decomposition)
	Creates an FFT object based on the given decomposition.
std::unique_ptr< IFFT >	pfc::fft::create_with_backend (const FFTLayout &fft_layout, int rank_id, plan_options options, Backend backend)
	Creates an FFT object with runtime backend selection.
std::unique_ptr< IFFT >	pfc::fft::create_with_backend (const Decomposition &decomposition, int rank_id, Backend backend)
	Creates an FFT object with runtime backend selection.

Detailed Description

Fast Fourier Transform interface for spectral methods.

This file defines the FFT class and related utilities for performing distributed parallel FFT operations using HeFFTe. OpenPFC uses spectral methods where derivatives and other spatial operations are efficiently computed in Fourier space.

The FFT class provides:

• Distributed-memory parallel 3D real-to-complex and complex-to-real transforms
• Integration with HeFFTe backend (supports FFTW, cuFFT, rocFFT)
• FFTLayout for managing real/complex data decomposition
• Helper functions for k-space operations (wavenumbers, Laplacian operators)

Typical usage:

// Create FFT for decomposed domain
pfc::decomposition::Decomposition decomp(world, MPI_COMM_WORLD);
pfc::FFT fft(decomp, pfc::fft::FFTBackend::Default);
 
// Transform to Fourier space
std::vector<double> real_data = ...;
std::vector<std::complex<double>> fourier_data = fft.forward(real_data);
 
// Compute derivatives in k-space, then transform back
// ... modify fourier_data ...
std::vector<double> result = fft.backward(fourier_data);

This file is part of the Core Infrastructure module, providing the foundation for spectral method computations in phase-field simulations.

See also

core/decomposition.hpp for domain decomposition

model.hpp for FFT usage in physics models

backends/heffte_adapter.hpp for HeFFTe integration

Enumeration Type Documentation

Backend

enum class pfc::fft::Backend

strong

FFT backend selection.

Specifies which FFT library backend to use for computations.

• FFTW: CPU-based FFT (default, always available)
• CUDA: GPU-based FFT using cuFFT (requires CUDA and OpenPFC_ENABLE_CUDA)

Enumerator
FFTW	CPU-based FFT using FFTW (default)
CUDA	GPU-based FFT using cuFFT (requires CUDA support)

Examples

/home/runner/work/OpenPFC/OpenPFC/include/openpfc/fft.hpp.

Function Documentation

create() [1/4]

FFT pfc::fft::create

(

const Decomposition &

decomposition

)

Creates an FFT object based on the given decomposition.

Parameters

decomposition

The Decomposition object defining the domain decomposition.

Returns

An FFT object containing the FFT configuration and data.

Exceptions

std::logic_error,if

decomposition size and rank size do not match.

Note

Precision (float/double) is determined by data types passed to forward/backward methods.

create() [2/4]

const FFTLayout pfc::fft::layout::create	(	const Decomposition &	decomposition,
		int	r2c_direction
	)

Creates an FFTLayout object based on the given decomposition and parameters.

Parameters

decomposition	The Decomposition object defining the domain decomposition.
r2c_direction	The direction of real-to-complex symmetry.

Returns

An FFTLayout object containing the layout information.

Examples

/home/runner/work/OpenPFC/OpenPFC/include/openpfc/fft.hpp.

create() [3/4]

FFT pfc::fft::create	(	const Decomposition &	decomposition,
		int	rank_id
	)

Creates an FFT object based on the given decomposition and rank ID.

Parameters

decomposition	The Decomposition object defining the domain decomposition.
rank_id	The rank ID of the current process in the MPI communicator.

Returns

An FFT object containing the FFT configuration and data.

Note

Precision (float/double) is determined by data types passed to forward/backward methods.

create() [4/4]

FFT pfc::fft::create	(	const FFTLayout &	fft_layout,
		int	rank_id,
		plan_options	options
	)

Creates an FFT object based on the given FFTLayout and rank ID.

Parameters

fft_layout	The FFTLayout object defining the FFT configuration.
rank_id	The rank ID of the current process in the MPI communicator.
options	Plan options for configuring the FFT behavior.

Returns

An FFT object containing the FFT configuration and data.

Note

Precision (float/double) is determined by data types passed to forward/backward methods.

Examples

/home/runner/work/OpenPFC/OpenPFC/include/openpfc/fft.hpp.

create_with_backend() [1/2]

std::unique_ptr< IFFT > pfc::fft::create_with_backend	(	const Decomposition &	decomposition,
		int	rank_id,
		Backend	backend
	)

Creates an FFT object with runtime backend selection.

Parameters

decomposition	The Decomposition object defining the domain decomposition.
rank_id	The rank ID of the current process in the MPI communicator.
backend	The FFT backend to use (FFTW, CUDA, etc.)

Returns

A unique_ptr to IFFT interface for the selected backend

Exceptions

std::runtime_error

if backend is not supported or not compiled in

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create_with_backend() [2/2]

std::unique_ptr< IFFT > pfc::fft::create_with_backend	(	const FFTLayout &	fft_layout,
		int	rank_id,
		plan_options	options,
		Backend	backend
	)

Creates an FFT object with runtime backend selection.

Parameters

fft_layout	The FFTLayout object defining the FFT configuration.
rank_id	The rank ID of the current process in the MPI communicator.
options	Plan options for configuring the FFT behavior.
backend	The FFT backend to use (FFTW, CUDA, etc.)

Returns

A unique_ptr to IFFT interface for the selected backend

Exceptions

std::runtime_error

if backend is not supported or not compiled in

Note

This function provides runtime polymorphism via the IFFT interface. For compile-time selection with zero overhead, use create() directly.

Examples

/home/runner/work/OpenPFC/OpenPFC/include/openpfc/fft.hpp.

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