Pscf::Pspc::FFT< D > Class Template Reference

Fourier transform wrapper for real data. More...

#include <FFT.h>

Public Member Functions
	FFT ()
	Default constructor. More...
virtual	~FFT ()
	Destructor. More...
void	setup (IntVec< D > const &meshDimensions)
	Setup grid dimensions, plans and work space. More...
void	setup (RField< D > &rField, RFieldDft< D > &kField)
	Setup grid dimensions, plans and work space. More...
void	forwardTransform (RField< D > const &in, RFieldDft< D > &out) const
	Compute forward (real-to-complex) Fourier transform. More...
void	inverseTransform (RFieldDft< D > &in, RField< D > &out) const
	Compute inverse (complex-to-real) Fourier transform. More...
void	inverseTransformSafe (RFieldDft< D > const &in, RField< D > &out) const
	Compute inverse (complex-to-real) Fourier transform without destroying input. More...
IntVec< D > const &	meshDimensions () const
	Return the dimensions of the grid for which this was allocated. More...
bool	isSetup () const
	Has this FFT object been setup? More...

Detailed Description

template<int D>
class Pscf::Pspc::FFT< D >

Fourier transform wrapper for real data.

Definition at line 30 of file pspc/field/FFT.h.

Constructor & Destructor Documentation

FFT()

template<int D>

Pscf::Pspc::FFT< D >::FFT

Default constructor.

Definition at line 23 of file pspc/field/FFT.tpp.

~FFT()

template<int D>

Pscf::Pspc::FFT< D >::~FFT

virtual

Destructor.

Definition at line 37 of file pspc/field/FFT.tpp.

Member Function Documentation

setup() [1/2]

template<int D>

void Pscf::Pspc::FFT< D >::setup

(

IntVec< D > const &

meshDimensions

)

Setup grid dimensions, plans and work space.

Parameters

meshDimensions

Dimensions of real-space grid.

Definition at line 51 of file pspc/field/FFT.tpp.

References Pscf::Pspc::RField< D >::allocate(), Pscf::Pspc::RFieldDft< D >::allocate(), and UTIL_CHECK.

setup() [2/2]

template<int D>

void Pscf::Pspc::FFT< D >::setup	(	RField< D > &	rField,
		RFieldDft< D > &	kField
	)

Setup grid dimensions, plans and work space.

Parameters

rField	real data on r-space grid
kField	complex data on k-space grid

Definition at line 69 of file pspc/field/FFT.tpp.

References Util::Array< Data >::capacity(), Pscf::Pspc::RField< D >::meshDimensions(), Pscf::Pspc::RFieldDft< D >::meshDimensions(), and UTIL_CHECK.

forwardTransform()

template<int D>

void Pscf::Pspc::FFT< D >::forwardTransform	(	RField< D > const &	in,
		RFieldDft< D > &	out
	)		const

Compute forward (real-to-complex) Fourier transform.

This function computes a scaled Fourier transform, which is obtained by dividing the unscaled transform computed by FFTW by the number of elements. A scaled copy of the input data is copied to a temporary real array before being passed to the FFT forward transform function.

This function does not overwrite or corrupt the input array.

Parameters

in	array of real values on r-space grid
out	array of complex values on k-space grid

Definition at line 125 of file pspc/field/FFT.tpp.

References Util::Array< Data >::capacity(), Pscf::Pspc::RField< D >::meshDimensions(), Pscf::Pspc::RFieldDft< D >::meshDimensions(), and UTIL_CHECK.

inverseTransform()

template<int D>

void Pscf::Pspc::FFT< D >::inverseTransform	(	RFieldDft< D > &	in,
		RField< D > &	out
	)		const

Compute inverse (complex-to-real) Fourier transform.

This function computes the same unscaled inverse transform as the FFTW library.

NOTE: The inverse transform generally overwrites and corrupts its input. This is the behavior of the complex-to-real transform of the underlying FFTW library. See Sec. 2.3 of the FFTW documentation at https://www.fftw.org/fftw3_doc, One-Dimensional DFTs of Real Data: "...the inverse transform (complex to real) has the side-effect of overwriting its input array, ..."

Parameters

in	array of complex values on k-space grid (overwritten)
out	array of real values on r-space grid

Definition at line 149 of file pspc/field/FFT.tpp.

References Util::Array< Data >::capacity(), Pscf::Pspc::RField< D >::meshDimensions(), Pscf::Pspc::RFieldDft< D >::meshDimensions(), and UTIL_CHECK.

inverseTransformSafe()

template<int D>

void Pscf::Pspc::FFT< D >::inverseTransformSafe	(	RFieldDft< D > const &	in,
		RField< D > &	out
	)		const

Compute inverse (complex-to-real) Fourier transform without destroying input.

Parameters

in	array of complex values on k-space grid
out	array of real values on r-space grid

Definition at line 166 of file pspc/field/FFT.tpp.

References Util::Array< Data >::capacity(), and UTIL_CHECK.

meshDimensions()

template<int D>

IntVec< D > const & Pscf::Pspc::FFT< D >::meshDimensions

inline

Return the dimensions of the grid for which this was allocated.

Definition at line 166 of file pspc/field/FFT.h.

isSetup()

template<int D>

bool Pscf::Pspc::FFT< D >::isSetup

inline

Has this FFT object been setup?

Definition at line 159 of file pspc/field/FFT.h.

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The documentation for this class was generated from the following files:

• pspc/field/FFT.h
• pspc/field/FFT.tpp